When you’re new to gardening, starting plants from seed might sound like an intimidating task. At least it did to me. Seed starting just looked like a lot of work that required the kind of gardening skill only master gardeners would possess.
But I moved out to my husband’s farm and was forced to face my seed starting fears head on. It turns out that seed starting is really not that difficult. You can do it, and I’ll show you how.
This article was updated January 2017. Updates are noted by italics.
Step One: Gather seed starting supplies
1.Seed starting mix
You will want a fine grain seed starting mix, aka germinating mix. The finer particles in a germ mix result in a much friendlier growing environment for the seedling. They allow for even moisture retention and settle evenly to prevent pockets of air and dense clumps of dirt.
Learn everything you need to know about starting from seed including how to make your own seed starting mix in my book, Seed Starting For Beginners.
2.Something to plant in
We use multi-cell seed starting trays. These are easiest for us because of the quantity of plants we want to grow, but you can use almost anything that has good drainage.
You’ll also need a clear dome lid to cover the tray.
For a home gardener, I like this seed starting kit which includes the plastic cells, a tray they sit in, and the dome which traps heat and moisture. Here is seed starting kit that includes all of that plus a heat mat which I will talk later in this post.
We always have one or two trays that we think we can get away with not using so many labels. We ALWAYS end up with unidentified plants which is fine if you are just eating them, but we can’t use these unidentified plants for breeding or seed sales.
Quick tip: For labels, cut up some old mini blinds into 4 inch long pieces and write on them with a permanent marker.
Just choose something small and waterproof. This is not the time for the pretty garden markers. You’ll use something prettier when you plant it out.
Hopefully, soon, you’ll be saving your own seeds, but for any you don’t have, choose your favorite seed supplier. I love Seeds for Generations, Baker Creek and Johnny’s, but there are tons of seed suppliers out there. Heck, even Wal-mart has seeds.
If you need suggestions on what to start, see my blog post: 5 Tomatoes You Should Grow
Your seeds need to be warm and cozy if you are going to coax the little baby plant out of them. Appropriate germination temperatures vary by type of plant. Check your seed packet for ideal germination temps.
My Garden Planning Spreadsheets will help you determine germination temps and dates.
If it is too cold, the seeds will rot and die. If it is too hot, they will cook and die. Don’t kill your seed babies!
The best way to keep them at the right temp is to put them on a seedling heat mat with a thermostat. This is not the same thing as a heating pad. Don’t use a heating pad. You will kill the seed babies.
You can purchase a heat mat on Amazon for around $20.
In a pinch, you can rest your seedling tray on top of your refrigerator. This should get you pretty close to the right temperature for germination for tomatoes and peppers. But, just in case, I would plant a few extra since you can’t regulate the temperature very well up there.
Step Two: get the seed starting mix into your trays
We take the germ mix and wet it down with a little water. Watering the germ mix before you fill the trays is very important because the dry mix is fluffier and looser. It is harder to work with, doesn’t fill the cells well, and you can end up with dry patches within the cell even after watering.
You’ve got the right amount of moisture when you squeeze the germ mix in your hand and it holds its shape but is not soggy.
To get the damp germ mix in the tray cells, spread the dirt loosely on top until all cells are filled. To prevent air pockets at the bottom of the cells, lift the tray a little and let it fall back down on the table. Then spread another layer of dirt as needed to top off. Don’t force the mix into the cells, you don’t want the soil tightly packed in the trays.
Here we have five trays ready to plant. Hubz is dibbling which just means poking holes for the seeds. He’s actually using an old nail head, but a pencil or pen is just the right size, too. Let the kids use their fingers. Or just grab whatever is around you.
It is not necessary to dibble before starting seeds. You can also rest the seed on top and then push gently on it with your finger to set it in. However, if you are working outside on a windy day, we recommend you dibble then drop and not the other way around. I just want to say dibble one more time. And now I’m done.
Step Three: label then plant seeds
I recommend labeling your tray before you start putting in seeds and working one variety at a time.
1. Write on label
2. Insert label.
3. Put in seed.
It is very important to go in that order. If you get distracted and forget which seeds you have started or which cells they’re in, you could be in a mess later. Many seeds are very, very tiny and you very likely will not be able to see them once they’re on the dirt.
Step Four: cover seeds
When all seeds are safely poked into their new homes, cover lightly with loose germ mix or use vermiculite and sprinkle it on top.
Vermiculite is a naturally occurring mineral that is mined and shredded to form the product we use in the garden. It is very light-weight and super absorbent. Seed babies easily push up and through vermiculite at germination.
When planting tomato seeds, we place one seed per cell. There are some reasons you would plant more than one per cell. If you aren’t sure of the viability of your seeds or can’t control their temperature and hydration definitely plant 2 or 3 per cell.
If you plant more than one per cell, and they all sprout, you may need to pick the strongest sprout and pluck the others.
Look at these trays of basil plants. See how many tiny plants there are per cell? With basil and many other herbs with tiny seeds, we sprinkle seed onto the germ mix and lightly cover with vermiculite.
As a side note, a lot of herbs do well when directly seeded into your garden, but make SURE the chance of frost has passed.
Step Five: water the seeds in
Once the seeds are safe in their new homes and cozy in their vermiculite blanket, water them well, but you don’t want them soggy. They will rot or mold if there is too much water.
Step Six: taking care of the seedlings
All you have to do is keep them warm and watered. We recommend using a tray with a clear lid to trap moisture and retain heat.
These trays are sitting on a 48″ heat mat and under two fluorescent grow lights.
Tomato and pepper seeds don’t need light to germinate. But the light provides some warmth, and they will need some light when the seed pops (pop=germinate=sprout) so you might as well go ahead and set them up.
You don’t need lights, you can use a window. However, seedlings grown in a window are prone to stretching which can create a flimsy, wimpy little stem.
Also, baby plants are very tender and fluctuations in temperature, as can happen in a window sill, can kill them. Investing in a heat mat and a light kit is really worth it. You’ll get a much higher germination rate and sturdier plants.
It will take 5-10 days for tomatoes to sprout, peppers can take up to 14 days, and most herbs will germinate after 5-7 days. Older seeds may take longer. Fresher seeds may be shorter.
These little guys were planted 6 days before this picture was taken. Aren’t they just so cute?
Seedlings are very tender, and they’ll need daily attention to keep them healthy.
How long do the seedlings stay on the heat mat and in the greenhouse?
What if they outgrow the starter tray?
What is hardening off?
When should you plant them out?
All of these questions and more are answered in my book, Seed Starting for Beginners.
When can you eat them?
It feels like forever, but really it takes about 3-4 months to get from seed to fruit. That is an excruciatingly long time, but oh the joy of your first tomato from the garden. It is a delight every single year.
A green tomato takes approximately 60-90 days to ripen on the plant. Seed to tomato definitely takes 3 to 4 months.
Herbs like basil, cilantro, and thyme can be harvested for leaves at around 6-8 weeks or whenever they have enough leaves to spare a few.
Peppers take about 90-120 days from seed to produce ripe fruit.