The start of the growing season is an exciting time. It’s kinda like deciding what birthday presents you’re going to get, then opening those gifts. And seeing a plant germinate from a seed is truly magic.

But growers don’t always have good luck getting seeds started. And with seedlings are fragile creatures–growers don’t always know how to care for them, when & how to transplant them successfully, how to avoid die-offs, and a host of other challenges.

It can be confusing & frustrating, despite your excitement & the magic of growing plants from seed.

In this master guide, we’ll cover everything you need to know so you can:

succeed at sprouting seeds, and
nurture your fragile seedlings so they become productive plants.

Let’s get right into it!

Why grow from seeds?

First off, why would you even want to grow plants from seed?

Isn’t it just easier to buy plants from the store?

Yes, it can be easier & quicker to just buy plants. But there are a bunch of reasons why you wouldn’t want to or simply can’t do that.

Advantages to growing from seeds:

Growing from seeds gives you an earlier start on the growing season–especially for heat-loving plants like tomatoes, basil, melons.
Growing from seeds gives you multiple crops per year, especially for cold-tolerant crops like greens.

Seeds are far less expensive than buying plants. A seed packet might cost $3–which can produce unlimited plants (if you harvest those plants’ seeds), while a single plant can cost $3-5.

Some plants can’t be bought. Many–maybe most–varieties of plants simply aren’t sold at all. You have to grow them from seeds. This is often true of native wildflowers.
Maximize your garden’s output: By early or mid-summer, it’s hard to buy seedlings–stores just don’t carry vegetable transplants. But if you’ve got seeds, you can double, triple, or quadruple your garden’s output by growing continuous crops of things like greens, beans, and peas.

Because seeing seeds sprout & grow is just plain magic.

Annuals, biennials, & perennials

Before we dive in, you’ll need to understand the difference between annuals, biennials, and perennials.

Plants typically fall into one of the following categories:

Annuals complete their entire life cycle–sprouting from seed, growing, flowering, and producing seeds–all in a single growing season. Common annual crops & flowers include: wheat, marigolds, watermelon, beans, lettuce, and corn.
Biennials complete their life cycle over 2 years. They produce seeds at the end of their 2nd growing season. Typically, biennials will overwinter as a rosette of green leaves on the soil surface. Leeks, cabbage, and parsley are biennials.
Perennials continue their life over several or many years. Perennials are very numerous, and common perennial plants include: trees, ferns, milkweed, currants, blueberries, raspberries & blackberries, strawberries, lavender, mints, oregano, many onion varieties, asparagus, potatoes, and kale.

Yes, there are exceptions, and some perennials can behave like annuals in warmer climates vs. cooler climates. For example, Black-Eyed Susans behave more like annuals in warm, southern climates, but more like perennials in cooler northern climates.

So, keeping these distinctions in mind is helpful to understand seed production & growing from seeds.

Seeds

A seed is an embryonic plant–basically a potential plant.

Seeds are produced by plants called gymnosperms and angiosperms, and seeds contain all the plant’s genetic information along with a bit of food for the fledgling seedling.

Gymnosperms have no flowers or fruits, but produce “naked” seeds, typically on cones or scales. Gymnosperms are an older group of plants, and include conifers (e.g., pines), gingkos, and cycads. Gymnosperms are typically wind-pollinated. Gymnosperms have been around for the past 320 million years.

Angiosperms are flowering plants, which often produce fruit. Seeds are enclosed within a ripened ovary of the flower–in other words, a fruit. Angiosperms are typically pollinated by wind or animals (including mammals, birds, and insects). Angiosperms evolved later, during the Triassic, along with dinosaurs.

Seeds range in size from a grain of sand up to coconuts. Yep, a coconut is just a single, giant seed.

OK, so a seed is basically a little genetic & food time capsule.

And most importantly, seeds let us grow plants.

How long can seeds last?

This is a great question–especially since you probably have packets of seeds laying around that are, like, 8 years old.

Will they sprout if you plant them?

It depends. Some seeds can stay viable for decades–even thousands of years.

An arctic flower called the narrow-leafed campion was germinated from seeds buried in frozen tundra for over 31,000 years. Yeah, that’s no typo: 31,000 freaking years.
Also, Judean date palm seeds over 2,000 years old were excavated from Herod the Great’s tomb and successfully germinated. You could be eating dates from a tree that an ancient king ate from.

But what about that heirloom Brandywine tomato seed packet from 2009?

Will those seeds germinate? Maybe.

As a general rule–especially for most garden plants–the older the seed, the less likely they’ll be to germinate. And, the probability of the seeds germinating depends on:

the plant variety

conditions it prefers
conditions under which the seeds were stored, and
conditions you give the seeds after planting.

Which brings us to our next topic: germination.

Germination

What is germination?

At its most basic level, germination is when a seed begins to grow.

There are 3 phases during germination:

Imbibition: This is when the seed absorbs water, and the seed coat softens. As the name implies, the seed “imbibes” water.
Interim (or “lag”) phase: During the interim phase, the switch gets flipped to “on” for all the seeds internal workings. Its cells begin to respire, and it starts metabolizing its stores of food.
Radicle & root emergence: The seed’s cells start dividing & reproducing, and the initial root–called the radicle–pokes out from the seed coat, and makes its way downward into the soil.

What do seeds need to germinate?

All seeds need 3 things to germinate:

Water
Warmth

Oxygen

And some seeds–depending on the species or variety–have additional requirements before they’ll germinate. The most common are:

Light

Exposure to cold
Scarification

Other special requirements, that usually depend on the environment where the plant grows.

For example, some seeds require exposure to smoke before they germinate. Weird, huh? Well, that’s because they’re adapted to fire-scarred landscapes–and after a fire burns an area, the seeds & its plants have an opportunity to colonize the fire-cleared landscape. So, they evolved to germinate after being exposed to chemicals in smoke–thus increasing the chances they’ll sprout after a fire. Cool, huh?

Water

Remember the imbibition phase of seed germination?

Well, without water:

the seed coat can’t soften–and thus the radicle & root can’t break through the seed coat, and
the seed’s embryo & endosperm can’t absorb water, swell, and start metabolizing.

Water gets the whole process started.

But too much water can drown the seed. More on that below in the “how to” section.

Warmth

The 2nd critical requirement for seeds to germinate is warmth. And this can be a bit of a Goldilocks rule–not too hot, not too cold, but just right.

Think of it this way: After winter, the warmth of early spring signals to plants that it’s time to start growing. Without the warmth, plants remain dormant.

So, to get your seeds started, you need to warm them up a bit.

Different plant varieties require different temperatures for germination. For example, check out the optimal germination temperatures below:

Basil: 95 degrees Fahrenheit (https://vtechworks.lib.vt.edu/bitstream/handle/10919/49553/Zhou_D_T_2012.pdf?sequence=1)

Spinach: 59 degrees Fahrenheit (http://www.hort.cornell.edu/expo/proceedings/2013/Leafy%20Greens/Leafy%20Greens%20van%20der%20Heide%20Germination%20and%20establishment.pdf)

In general, you can follow the Goldilocks rule: not too hot, not too cold.

Here’s a run-down on minimum, maximum, and optimal temperatures for germinating some common garden plants (courtesy of https://extension.psu.edu/seed-and-seedling-biology):

	Minimum (F)	Optimum Range (F)	Optimum (F)	Maximum (F)
Beet	40	50-85	85	85
Cabbage	40	45-95	85	100
Cauliflower	40	45-85	80	100
Celery	40	60-70	70	85
Chard	40	50-85	85	95
Cucumber	60	60-95	95	105
Eggplant	60	75-90	85	95
Lettuce	35	40-80	75	85
Melons	60	75-95	90	100
Onion	35	50-95	75	95
Parsley	40	50-85	75	90
Pepper	60	65-95	85	95
Pumpkin	60	70-90	90	100
Spinach	35	45-75	70	85
Squash	60	70-95	95	100
Tomato	50	70-95	85	95

But what if you don’t have a sufficiently warm spot to germinate your seeds?

One common option is to use germination mats–also called seedling heat mats. These mats let you to set the temperature according to your seeds’ requirements. For example, peppers prefer warm temps–they’ll germinate in 8 days at 86° F, but will take more than 13 days to germinate at 58° F.

I dunno about you, but I’m impatient. The quicker I can get seeds to germinate, the happier I am.

So, if you don’t have a sunny window for your seeds, you can put them on top of your refrigerator. Or get a heat mat–they’re reasonably priced.

Oxygen

Yep, our good friend oxygen. Without it, most life on Earth wouldn’t exist.

Seeds are no different.

Without oxygen, seeds won’t germinate. That’s because oxygen is needed for cell metabolism. With a bit of oxygen, the cells inside your seeds start they machinery, and the seed will sprout.

And once the seed germinates, the young seedling needs oxygen too.

But too often, growers overwater both their seeds and their seedlings. The result is rotting seeds or drowned seedlings.

Neither is pretty.

Yep, seedlings–and any plant–can literally drown if it’s in too much water, since it can’t get oxygen.

Special germination requirements

So most garden-variety plants–peppers, tomatoes, greens, etc.–just need water, warmth, and oxygen to germinate.

But other plants–typically wildflowers & other non-domesticated plants–might need special treatment to get their seeds to germinate.

Light

Most seeds germinate best in the dark–under the soil. And some seeds may not even germinate if exposed to light–like many species in the Allium genus–like onions, garlic, chives, etc.

But some species actually require exposure to light before they’ll germinate. The most common that require light are:

Begonias
Coleus
Primula

Lettuces
Dill

The chart below shows light requirements for various annual flower & vegetable varieties (courtesy of https://hortnews.extension.iastate.edu/2017/01/seed-germination-guide):

	Light*
Annuals
Snapdragon	L
Wax Begonia	L
Periwinkle (Vinca)	C
Celosia	C
New Guinea Impatiens	LC
Geranium	C
Petunia	L
Scarlet Sage (Salvia)	L
Coleus	L
Marigold	C
Pansy	LC
Zinnia	C

Vegetables
Onion	LC
Dill	L
Kale	C
Cauliflower	C
Cabbage	C
Broccoli	C
Pepper	C
Watermelon	C
Muskmelon / Cantaloupe	C
Cucumber	C
Squash and Pumpkin	C
Tomato	C
Basil	C
Parsley	C
Eggplant	C

* “L” means that the seed variety requires light to germinate, “C” means the seed needs to be covered to germinate, and ”LC” varieties should be lightly covered.

Cold

Probably the most common requirement for seeds from temperate climates is exposure to cold. So, if the plant grows in a place where the temperature stays below freezing during winter, it’s likely that the seeds need exposure to cold before they’ll germinate.

Yeah, you might be able to germinate seeds without the cold, but you’ll get much higher germination rates (i.e., the percentage of seeds that germinate vs. the total number of seeds you plant) if you expose them to cold.

That’s because those seeds have evolved so that the seeds’ cell machinery functions best during cold conditions, preparing the seed for germination once things warm up.

Technically, these seeds have chemical or metabolic conditions that prevent germination. The technical term for this is chemical dormancy. The most common chemical dormancy factors are certain plant hormones–like abscisic acid, which inhibits germination, and gibberellin, which ends seed dormancy. To break chemical dormancy, exposure to cold–or water, which leaches those chemicals from the seed–is required.

Exposing your seeds to cold for a period of time is often called stratification. The name “stratify” or “stratification” comes from the technique of layering seeds in a moist medium–like soil–for a period of time.

The easiest & most reliable way to expose your seeds to cold–so that they’ll germinate–is to:

Mix the seeds in a little soil with enough water to make things moist but not soggy.
Put the mixture in a plastic zip-locking bag, label it with the seed type & the date.

Put the bag in the back of your refrigerator for 6-8 weeks. Set a calendar reminder for yourself to take the seeds out so you can start planting.

Scarification

The other most common special germination requirement is scarification. Like the name suggests, these seeds need to be scarred, scored, or abraded a bit for them to germinate.

Essentially, these seeds have extra tough seed coats that won’t absorb water & start the germination process until the seed coat is breached.

In nature, scarification happens through:

exposure to fire,
having the seeds be exposed to flooding, often in a sandy area, or

Being eaten & then pooped out by an animal (the acid in the animal’s stomach scarifies the seed coat)

The most common seeds that require scarification are legumes–like lupines & mesquites. Cultivated beans like green beans & peas don’t require stratification.

The most common ways to scarify seeds are:

Rough up the seed coat with sandpaper, a file, or other abrasive material, or
Treating seeds in a dilute acid solution (this is how commercial growers typically scarify their seeds before planting).

Do you have to scarify seeds? No, but your germination rate will be MUCH higher for some species. One study found a 50% increase in germination rates by scarification (https://www.tandfonline.com/doi/abs/10.1080/03015521.1975.10425778).

How many seeds to plant?

Should you plant just 1 seed if you want only 1 plant?

Or just plant the entire seed packet?

Both options are less than optimal.

Think of it this way: As a grower, you’re actually like a statistician or your favorite variety of math nerd. You’re actually dealing with probabilities. Not all seeds will sprout or grow into mature, producing plants. You’ve got to hedge your bets, and plant more seeds than you actually want to grow into mature plants.

Worst case is you can give some seedlings away.

Also: Seeds are inexpensive.

So, plant more than you think you need.

That’s partly why seed packets–like watermelon–tell you to “plant 3 seeds” in each spot.

No, it’s not like the shampoo instructions to “wash, rinse, repeat”. Remember: not every seed will germinate. Also, not every seedling will survive, and not every seedling will thrive.

Tilt the odds in your favor that you’ll end up with enough mature, productive plants: plant more seeds.

Speeding up germination:

Now you know what seeds need: water, warmth, and oxygen–and maybe a couple other factors, depending on the plant.

So, you can probably guess what you can do to speed up germination:

Increase the water: soaking seeds
Increase the temperature

Soaking to speed up germination

Yep, soaking does indeed speed up germination. Research on various species suggests that germination can be sped up by roughly 20% by soaking the seeds. https://www.jstor.org/stable/23432612?seq=1

In my own anecdotal test, I planted cucumber seeds, which are supposed to germinate in 7-10 days. Mine germinated in 3 days–just 3 days! With tomatoes–which take a bit longer, 10-14 days–mine germinated in 7 days. Not too shabby.

So why does soaking speed up germination?

Soaking does 2 main things to speed germination:

Swells the seed, breaking the seed coat
Leaches out chemical inhibitors to germination

How long should you soak seeds? Only 6 – 24 hours. Longer than that, and you risk lowering your germination rate and having your seeds rot.

Increase the temperature to speed up germination

Excessively low or high temperatures decrease germination rates for many species of both wild & cultivated plant seeds.

Once germination occurs, the optimum growing temperature for seedlings is about 10 degrees Fahrenheit cooler than the optimum germination temperature (https://hortnews.extension.iastate.edu/1996/2-9-1996/seed.html).

So, if you’ve got an unheated greenhouse, don’t expect to germinate seeds in it unless the temperature is consistently at least 60 degrees Fahrenheit.

Likewise, if the temperature is over roughly 90-95 degrees, it’s unlikely your seeds will germinate.

So, a Goldilocks zone of around 70-80 degrees is optimal for most garden vegetable varieties. Refer to the chart above for specific temperatures for different plants.

Quickest method to germinate seeds

OK, all that said, here’s the quickest method I’ve found to germinate seeds.

With this method, I’ve gotten germination rates of 90-100%, compared to 0-50% when planting in soil.

And best of all, you can literally see the seeds germinating. It takes the guesswork out of trying to know whether your seeds have actually germinated–or are just a bust.

Here’s the method:

Soak the seeds in a small cup of water for 12-24 hours. It’s easiest to keep the seeds in water for a day, then do the next step.
Fold the seeds into a paper towel. Label the paper towel with a ball-point pen (its ink won’t run when wet). Lay the seeds out–with a little space between them–on a wet but not sopping paper towel. Fold the paper towel in half twice.
Put the paper towel in a plastic bag. I keep the plastic bag slightly open to prevent mold. Keep the bag in a room-temperature spot.

Check on the seeds daily, and plant when you see the root emerge. Depending on the type of seed, you should see seeds germinate in 1-3 days. When their root pokes out, they’re ready to plant in soil.

Super simple. I guess that’s why preschool & elementary school teachers have been doing it for years. It’s simple, visual, and extremely effective.

Now, if you have a commercial greenhouse where you’re literally growing millions of plants, could you do this? Yes, though you’d probably need to adapt it for scale. But the process would be the same.

===INSERT PHOTOS OF EACH STEP (SEEDS IN WATER CUP, SEEDS ON PAPER TOWEL, SEEDS GERMINATING ON PAPER TOWELS)===

How to save seeds

Now that you’re a germination ninja, you’ll be able to build a seed army in perpetuity. Every crop of plants you grow will produce more seeds. And if you’re a wildflower junkie like me, you can collect & grow your favorite wildflowers.

But, you have to know when the seeds are ready to collect. Collect them too soon, and you won’t have viable seeds. And if you wait too long, the seeds might scatter before you collect any.

Most common garden plants & wildflowers can be grown from seeds. However, while some plants CAN be grown from seed, it might not be practical.

For example, avocados & lemons can be grown from seed, but will take years to produce fruit, and generally produce less fruit–and the fruit produced is typically inferior. Waiting years to grow your own avocados from seed only to find out it’s “meh” would be pretty disappointing. Better to buy a small plant, then let it reach maturity sooner & produce better fruit.

To save seeds:

Check on the plant. Mature seeds are generally darker in color and harder than not-yet-ripe seeds. Often, when the seeds are ripe, you’ll see some of the flower heads will have seeds that are already falling off.
Collect the seeds and put them in your favorite seed packet. I’ve got a super simple printable template here. Make sure to write the plant name & date collected on the packet.
Store your seeds in an appropriate location:
1. If your seeds don’t need cold treatment (i.e., “stratification”), you can just put them in a cool or room-temperature location.
2. If your seeds DO need cold treatment to germinate: Do the following 6-8 weeks before planting:
  1. Mix the seeds in a little soil with enough water to make things moist but not soggy.
  2. Put the mixture in a plastic zip-locking bag, label it with the seed type & the date.
  3. Put the bag in the back of your refrigerator for 6-8 weeks. Set a calendar reminder for yourself to take the seeds out so you can start planting.

Seedlings:

OK, next, you’ll need to understand what seedlings are & what they need–because a seedling isn’t just a mini version of the mature plant.

Cotyledons & true leaves

Cotlyedons–ever heard of them? Most growers haven’t. But chances are that you’ve seen them & kinda know what they are. Here’s the run-down:

Cotyledons are the leaves that first appear on the seedling. Cotyledons are part of the seed, and provide energy for the growing seedling. Cotyledons do NOT look like the mature leaves of the plant–they’re typically shaped like the seed.
True leaves emerge after the cotyledons, and look like the typical leaves that the mature plant produces.

===INSERT IMAGE showing cotyledons vs. true leaves===

Most plants that you grow will have 2 cotyledons. Think of a bean seed:

===INSERT bean seedling with dicots===

But some plants only have 1 cotyledon. For example, grasses, irises, lilies, and corn are all monocots.

So if a plant has 2 cotyledons, it’s a dicot, and if it has just 1 cotyledon, it’s a monocot.

Why should you care about cotyledons vs. true leaves?

Well, next time you’re playing Scrabble, you can bust out the word “dicot” for bonus points.

But beyond that, if you’re germinating seeds indoors, you’ll generally want to wait until the first true leaves emerge before transplanting your seedling (https://extension.umd.edu/hgic/topics/seedling-care).

Also, there’s no need to fertilize your plants until after the first true leaves appear (https://www.uvm.edu/vtvegandberry/factsheets/growingtransplants.html).

What do seedlings need?

Generally, seedlings need a bit gentler care than mature plants.

Like seeds & mature plants, seedlings need water, warmth, and oxygen, but also need light.

Light

If you’re starting seeds in late winter and live in a cloudy climate, seedlings may not get enough light on a windowsill. Seedlings show that they need more light be getting long & stringy, and bending or reaching toward the light.

So, it’s often best to supplement their natural light with grow lights–like LED lights, which are energy efficient, and provide the best spectrum for plant growth.

Oxygen

I already mentioned this above with seed germination, but seedlings–and plants in general–need oxygen at the root zone, otherwise they’ll drown & die.

So, when you water your seedlings, just make sure the soil or planting medium is moist but not soggy.

Room to grow: Thinning & Transplanting

As your seeds sprout & begin their tiny lives, you’ll might have more seedlings than you need. Or, they might look like they’re all crowding one another.

That’s the time to thin them out: remove some seedlings so the rest can grow.

Yeah, I know: you invested all this emotional energy into those teeny seeds, and the last thing you want is to kill off part of your mini-crop.

I get it.

But consider these facts (https://lancaster.unl.edu/hort/articles/2007/thinplants.shtml):

Plants that are crowded compete for nutrients–meaning that every plant is getting fewer nutrients, and so probably won’t reach its potential.
Thinning increases air circulation between plants, thus preventing diseases like fungal infections & damping off.

If you’ve ever had an entire tray of seedlings die off in a matter of days from damping off, you understand how important it is to thin seedlings.

Instead of throwing those tiny seedlings away, you can transplant them–and even give them away to friends & family.

If it’s getting warmer outdoors, you can harden off the seedlings before planting them directly outside.

Otherwise, you can carefully transplant your seedlings into slightly larger pots. Peat pots are great, because you can plant them directly in the soil.

How deep to transplant?

For tomatoes, peppers, and watermelon, planting up to the first true leaves has been experimentally shown to increas production between 64-70% (https://swfrec.ifas.ufl.edu/docs/pdf/veg-hort/transplant/t_trans.pdf and https://edis.ifas.ufl.edu/pdffiles/CV/CV10400.pdf). Yeah, crazy! Just from planting the seedlings a bit deeper.

Protection from varmints–including indoor varmints

Lousy, good-for-nothin’ varmints.

In just a few short seconds, a hungry–or curious–varmint can destroy weeks of growth, re-setting the clock on your careful planning & planting.

In my house, we’ve got a cat who’ll mow down seedlings the first chance she gets. Argh! Super frustrating to come home from work, only to find a few lonely green stems poking above the soil, all their leaves chewed off.

Yeah, and cats are supposed to be carnivores, not herbivores. Tell that to my cat…

So, learn from my mistake, and put your seedlings somewhere your cat, dog, or guinea pig can’t get to them. Plastic enclosures work great–just make sure they’re slightly vented, otherwise you risk your tender seedlings roasting in the sun or rotting in the humidity.

To fertilize or not

Most seedlings won’t need fertilizing until after their first true leaves appear, since the cotyledons supply most of the energy & nutrients needed by the seedling.

Plus, potting soil or other growing medium typically has enough nutrients for the first few weeks of growth.

Hardening off

You might not be familiar with “hardening off’, but it’s super useful, and your tender seedlings will thank you for it by thriving instead of dying.

So what is “hardening off”?

Think of it this way:

When it’s February, you’re OK walking outside for a few minutes in a snowstorm–without a jacket–to get the mail or scrape the ice off your car. You’re used to the cold. A warm day at 40 degrees, and you start wearing shorts outside.
But in August, when you go into that walk-in cooler at Costco to get some grapes, and in less than 5 minutes, you’re shivering. But that walk-in cooler is still probably 40 degrees.

What gives?

That’s because in February, you’ve gotten used to the cold. You’ve been hardened to it by spending time in the cold for weeks.

Same thing with plants.

You can’t just put a plant outside for a 35-degree night if it’s been growing in your kitchen. It’ll either die or go into shock.

So, you need to harden it off: Gradually introduce it to the environment & location where it’ll eventually grow. Maybe an hour or 2 at first, then over several days, increase the amount of time your plant is outdoors so that it acclimates.

Transplant stress occurs due to low soil moisture, wind, heat, and excess light. Plants need to be introduced to these conditions gradually over 7 to 10 days. A cold frame or hoop house can be an ideal way to harden plants, since cold frames & hoop houses exposure plants to cool nights, high light, and some wind–but without stressing the plants.

Then, you’ll be assured that your delicate seedlings will thrive.

Now, if you’re a nerd like me, you’ll be curious about what happens during hardening off (https://lancaster.unl.edu/hort/articles/2007/hardentransplant.shtml). Here ya go

Plant growth slows (don’t worry, this is needed for your plant to thrive later, outdoors)
The amount of water in cells decreases–minimizing the risk of the plant freezing.
Cell walls develop more lignin (which provides harder structure for the plant)
Root development is increased.
Carbohydrates increase, boosting the plants stored food reserves.
Natural waxes on the leaves thicken, allowing the plant to be exposed to the sun and wind without dessicating.

How-to’s

OK, so now that your brain is crammed chock-full of info, let’s boil it down.

Below, you’ll find how-to instructions for:

Germinating seeds
Transplanting seedlings
Hardening off seedlings

Germinating seeds

Tricks:
1. Pre-soak seeds in water for 6-24 hours prior to planting.
2. Boost the temperature to 70-80 degrees Fahrenheit until your seeds germinate.
3. Plant more seeds than you need–they won’t all sprout or thrive.
4. Check seeds daily! You want to ensure they have just the right amount of moisture–but not too much. Dried-out seeds just plain won’t germinate, and water-logged seeds will rot.
5. Monitor temperature: Some plants like it warmer than others, while other plants don’t like it hot.
Steps:
1. Soak the seeds in a small cup of water for 12-24 hours. It’s easiest to keep the seeds in water for a day, then do the next step.
2. Fold the seeds into a paper towel. Label the paper towel with a ball-point pen (its ink won’t run when wet). Lay the seeds out–with a little space between them–on a wet but not sopping paper towel. Fold the paper towel in half twice.
3. Put the paper towel in a plastic bag. I keep the plastic bag slightly open to prevent mold. Keep the bag in a room-temperature spot.
4. Check on the seeds daily, and plant when you see the root emerge. Depending on the type of seed, you should see seeds germinate in 1-3 days. When their root pokes out, they’re ready to plant in soil.

Thinning & transplanting seedlings

Thin plants out if they’re crowding each other.
Transplant seedlings after their first true leaves appear.
For tomatoes, peppers, and watermelon, transplant depth should be up to the first true leaves.
Do NOT lift seedlings by their stem. Instead, gently lift seedlings out from their container by using a pencil, popsicle stick, or similar tool to lift the seedling & its soil from below.

Hardening off seedlings

Over 7-10 days, gradually introduce your plants to the area where they’ll grow.
Pay attention to how much wind, heat, and sunlight they receive during the hardening-off period.

Saving seeds

Collect the mature seeds and put them in your favorite seed packet. I’ve got a super simple printable template here. Make sure to write the plant name & date collected on the packet.
Store your seeds in an appropriate location:
- If your seeds don’t need cold treatment (i.e., “stratification”), you can just put them in a cool or room-temperature location.
- If your seeds DO need cold treatment to germinate: Do the following 6-8 weeks before planting:
  - Mix the seeds in a little soil with enough water to make things moist but not soggy.
  - Put the mixture in a plastic zip-locking bag, label it with the seed type & the date.
  - Put the bag in the back of your refrigerator for 6-8 weeks. Set a calendar reminder for yourself to take the seeds out so you can start planting.

Equipment:

The good news is that germinating seeds and growing seedlings doesn’t require much equipment.

However–and beware!–once you start seeds, you might quickly have an avalanche of seedlings that will need care & planting within a matter of days.

But that’s a good problem!

So here’s what you’ll need:

Soil / potting medium
Seeds (plus paper towels & plastic bags to help germinate them)
Containers
Labels
Optional:
- Heat mats
- Grow lights

Soil / potting medium:

So, technically, soil is NOT what you’ll be putting in pots.

“Soil” usually refers to topsoil–the top couple of feet of soil excavated from a particular location. It may have rocks, organic matter, sand, microorganisms, and who-knows-what in it. Topsoil can often become waterlogged & soggy–especially if it’s high in clay.

Plus, regular soil can harbor diseases & pests.

Potting medium is different, and is what you ultimately want (https://edis.ifas.ufl.edu/pdffiles/CV/CV10400.pdf). It’s mostly:

peat moss,
compost, and
vermiculite,
along with some minor ingredients to boost fertility.

The difference between potting medium and soil is that potting medium is specifically for growing plants–not just some topsoil that’ll be dumped on your yard for who-knows-what.

Most commercial growers use a soil-less mix of peat, perlite, and fertilizer. These mixes typically include some phosphorus, lime, micro-nutrients, and a surfactant to improve wetting capabilities of the mix.

Top-off the potting mix with vermiculite, since vermiculite holds water in, which reduces water loss from evaporation. Vermiculite also reduces large swings in temperature, providing for a more uniform germination environment.

Potting medium retains moisture well but also allows oxygen to get to roots.

Seeds

Obviously you need seeds.

And, to maximize your germination rate–i.e., the percentage of seeds that actually sprout–you’ll want to follow the method I outlined above: soaking seeds, then putting them on damp paper towels in plastic bags.

For seeds, newer is better. That way, you’ll maximize your germination rate. As seeds age, their germination rate often plummets, and you can end up with no seeds sprouting–truly disappointing!

Recommended seed sources are listed at below.

Containers

You’ve got lots of options here:

Seed trays
Peat pots
Virtually any container: Starbucks cups, clear plastic orange/apple juice jugs, etc.

Your choice depends on how much you’re planting and how much room you have. Seed trays are better for growing lots of plants, but with lots of seed trays, you’ll need a rack or some way to stack them while giving seeds & seedlings air & light.

For DIY seed trays, you can even use plastic or aluminum trays from sheet cakes. Mmm, cake…

If you’re re-using containers from prior years, make sure they’re clean. The last thing you want to do is introduce diseases & pests to your baby plants.

Coverings: You’ll want something to cover your seed containers if:

Your seeds will be in a place where they’ll dry out quickly
You have varmints–like mischievous housecats–who’ll decimate your growing crop.

Seed trays often come with clear plastic coverings, and so do Starbucks cups (if you’re using those for planting seeds).

Trust me: If you have animals, cover your tender seedlings. It’s incredibly frustrating to baby your 2-week-old seedlings, only to have your cat destroy them in 10 seconds.

Labels

Simple is best, but you do need labels. Some seeds & seedlings look very similar, and it’s easy to confuse them.

You can use:

Tape (I prefer painter’s tape, since it’s easy to remove)
popsicle/craft sticks

The label should include the:

Plant name/variety
Date planted (that way you know if those 7-year-old tomato seeds that you planted 25 days ago are simply never going to sprout)

Heat mats

Seedling heat mats are great for greenhouse gardening in colder temperatures & colder times of year.

Heat mats have been found to cut germination periods in half, which is significant, especially if you want to plant several cycles’ worth of produce!

Think of it as an incubator for plants—just like eggs need warmth to hatch, plants will grow more quickly and healthily with warmth.

The heat mat specifically provides bottom heat, which is what helps the plants germinate so much more quickly than growing without a heat mat.

Grow lights

Grow lights–especially LED grow lights, since they’re so energy-efficient–work well when it comes to growing plants indoors. They’re useful for indoor greenhouses because they give indoor plants the light they need since the indoor plants don’t naturally get it from the sun–especially during winter.

For growing seedlings–since you’ll often grow them in late winter or early spring when there’s less sunlight–grow lights can provide the additional light that seedlings need to grow vigorously.

With insufficient light, seedlings get long & leggy. That’s the key indicator that your seedlings need more light.

Seed types (cutting through the confusion)

There’s a saying among commercial growers: Good seed doesn’t cost, it pays.

But there’s a lot of confusion about different kinds of seeds–non-GMO, organic, heirloom, hybrid, magic beans, & what-have-you.

How’s a grower to decide between all these types of seeds?

GMO vs. non-GMO
Organic vs. non-organic
Heirloom
Hybrid
Natural
Treated vs. untreated

Here’s the deal:

GMO vs. non-GMO	GMO means “Genetically Modified Organism.” And while technically, a cocker spaniel is a GMO–since it doesn’t exist naturally in the wild–for our purposes, we’re talking about lab-engineered GMOs. And guess what? Unless you’re an industrial-scale farmer, you have no access to GMO seeds. In fact, there are only 12 genetically engineered crops approved in the US, and only 10 of those are currently produced. Most of these are commodity crops that home gardeners would never grow–like cotton, sugar beets, canola, and alfalfa (https://communityenvironment.unl.edu/translating-language-seed-packets-hybrid-heirloom-non-gmo-and-more). Plus, to purchase GMOs, you have to sign an agreement with the GMO patent-holding company that you won’t misuse or propagate the GMO.So, labelling seeds “non-GMO” is simply a marketing ploy by seed sellers. ALL seeds available to home gardeners are non-GMO.
Organic vs. non-organic	Organic seeds were produced on plants that received no synthetically produced fertilizers or pesticide sprays. However, it does NOT mean that the plants were not treated with pesticides, since there are organic-approved pesticides. That being said, given the many reputable studies that’ve been done:No evidence has shown that seeds contain pesticide traces.No evidence has shown that plants translocate pesticides into their fruit or seeds.Besides, since seeds are inside the fruits, even if there were pesticide residues in the seeds, it’d be such a miniscule amount that it’d be so dilute in the mature plant that it’d be below any threshold of threat to human or wildlife health.Bottom line: Buy organic if you’re OK paying significantly more for equivalent seeds. Otherwise, there’s likely no difference between organic vs. non-organic seeds.
Natural	Unlike “certified organic” or “USDA certified organic”, the term “natural” has no recognized definition by the USDA or any other legit organization. So seeds are labelled “natural” simply as a marketing ploy.
Heirloom	Heirloom seeds are generally those pre-dating 1951, when the first hybrid plants were introduced. Heirloom plants are open-pollinated, meaning that pollination occurs naturally by insect, bird, wind, or animal.Seed produced by the heirloom variety will grow true to type–in other words, it’ll resemble the parent plant–as long as the flowers were pollinated by the same variety. Open pollination creates a more genetically diverse gene pool which allows plants to slowly adapt to local growing conditions.
Hybrid	Hybrids, technically speaking, have 2 different parents. You are a hybrid of your mom & your dad.In the case of seeds & plant varieties, agricultural researchers & farmers create hybrids by crossing 2 specific varieties.Hybrid plants tend to have more resistance to diseases and pests compared to heirloom plants, since breeders actively work to boost resistance in hybrids. That means you’ll get higher-quality produce with fewer inputs. That’s why hybrids are popular with farmers: nicer, cleaner-looking fruits, with fewer pesticides. Also, hybrids are usually more productive, thanks to a phenomenon called hybrid vigor.Important caveat: The seeds produced by hybrid plants will often either be sterile (i.e., not produce fruits) or will NOT be like the hybrid (i.e., it’ll be like either of the hybrid’s parents). So, feel free to grow hybrids, but don’t bother saving their seeds. To dive into the genetics about why that is, F1 hybrids vs. homozygous breeding lines, check out a clear & detailed explanation here: https://ipm.missouri.edu/MPG/2014/8/Why-Not-Save-Hybrid-Seeds/
Treated vs. untreated	Treated seeds have one or more pesticides–i.e., fungicide or insecticide–to protect against pathogens or pests, primarily in the early stages of growth. If you’ve ever seen bright pink or orange seeds for corn, peas, or beans at a feed or farm store, those are treated seeds. And, yes, there are organic seed treatments, so treated seeds can also be organic.Bottom line: Treated seeds generally aren’t available for home gardeners.

If you want to geek out on all the details, a few reputable rabbit holes to go down are here:

Seed sourcing:

OK, now that you’ve filled your brain with the gist of different seed types, where can you score the ones you want?

Yes, you can get your seed from the local or big-box hardware/garden store–and you’ll do just fine.

But you might want to support small, local, or region-specific seed producers.

One thing you might want to consider is getting seeds that are adapted to your local climate–especially if you live in the arid Southwest, the cold upper Midwest, etc.

Generally, many people have had good results with seeds from the following:

You can find good lists of seed suppliers for your specific area by doing a Google search like the following (change “Minnesota” to whatever state or province you’re in):

Minnesota extension seed sources site:*.edu

Also, some master gardener programs maintain lists of recommended varieties. A nice list from the University of Minnesota Extension Service is available.

Common problems & fixes:

Despite your best efforts, you might run into problems. It can be a bummer to tend to your seeds & delicate seedlings, only to have them die off.

But, if you know the most common problems & their causes, you can usually prevent those problems.

Generally, you can prevent the most common problems with:

Sterile, nutrient rich potting mix.
Keeping soil moist but not soggy.
Providing adequate ventilation.

Here’s a quick rundown of the most common seedling problems:

Problem	Cause	Fix
Damping off: Seed collapse at base of stem, often with fungus present	Fungi & pathogens (typically Rhizoctonia spp., Fusarium spp., and Pythium spp.). Caused by soil being too wet and/or seedling overcrowding (which prevents good ventilation).	Unfortunately, seedlings affected by damping off rarely survive. It’s best to just start over, germinating a new batch of seeds.Use clean trays, pots, tools, and sterile potting media.Don’t overwater–soil should be moist but not soggy.Proper ventilation & don’t overcrowd seedlings.
Wilted seedlings	Overwatering: Basically, the seedlings start drowning by not getting enough oxygen.	Use well-drained soil, and keep soil moist but not soggy.
Dried-out leaves	Underwatering or temperature is too hot.	Keep soil moist but not soggy.For most seedlings, temperature should be 70-85 degrees Fahrenheit.
Spindly/leggy growth	Inadequate light. As the seedling reaches for more light, the long stems become weak.	Give seedlings more light, either sunlight or grow lights.
Leaf damage (e.g., chewed leaves or small dots on leaves)	Insects, such as fungus gnats. Often caused by soggy soil.	Keep soil moist but not soggy.Provide adequate ventilation.
Yellow-green seedlings	Nutrient deficiency–usually nitrogen.	Plant seeds & seedlings in media rich in nutrients, like compost, or apply a dilute fertilizer every 2 weeks.