Note: I’ve now started selling the organic fertilizers and microbial inoculants mentioned in this post. You can read more about that here.
You can get the jump on spring by starting plants from seeds.
Some plants pretty much need this, especially heat-loving plants like tomatoes, eggplants, and peppers being planted into cooler climates.
A few others such as carrots and squash really dislike being transplanted, so it’s best to directly sow them in the garden when the time is right.
For the rest, it’s up to you whether you’d like to get a head start by starting seeds indoors. I actually have a couple of trays going right now in order to test the germination of some of my saved seeds and to test some new seed sources of perennial greens I’m going to be growing. I’ll harvest all of these next month and then start seeds again for the garden.
It’s best to start most vegetable seeds 4-8 weeks before your last frost date in the spring, which you can look up here for U.S. cities and here for Canadian cities, or you can search online for your city/country.
The last frost date in Toronto, Ontario is May 9, while the date in San Antonio, Texas is Feb 28.
That means for many of my readers, the time to start planting seeds indoors will be somewhere between early January and early April.
And if you’re new to starting seeds, it’s great to do a practice run to get comfortable with the process, because it takes a bit of experience to get good at it.
You can also continue starting seeds indoors throughout the year, to be moved into the garden gradually as you harvest the early stuff.
For containers, I prefer multi-cell trays, rather than seeding all in one tray and separating later.
That way I can move plants directly into the garden when ready, rather than making extra work and disturbing the roots twice by potting them up, but that’s just my preference.
Put those trays into another big tray to catch water, and have a dome for placing on top to keep it nice and humid in there.
Most conventional commercial potting mixes contain chemical fertilizers and a high percentage of peat.
Those chemical fertilizers can cause various problems for the health of your plants.
The peat is mined from threatened, slow-growing bog ecosystems, is very difficult to wet once dried, and holds water so tightly that roots can rot when it’s saturated.
So I don’t tend to use it much, but I also don’t mind if you use a little because it does seem to help with germination.
And for most people who want to start simple, I do recommend buying organic, chemical-free potting mixes, perhaps certified on the package by the Organic Materials Review Institute (OMRI), most of which do still contain peat.
If you’re doing a lot of starting plants from seeds, you’ll save money by making your own. There are all sorts of recipes out there, but I keep mine simple.
I make my potting mix from approximately equal parts screened compost, course sand, and good soil. Sometimes I’ll add perlite if I feel the mix needs lightening up so it doesn’t get too compacted.
The advice is often to make a sterile mix, but I don’t do that because creating a biological void invites opportunistic organisms.
Instead, I introduce the organisms I want, both in high-quality compost and a touch of effective microorganisms.
Light And Heat
When starting plants from seeds, you’ll need a place with at least 8 hours of direct sun each day.
But that can be difficult, especially in the winter, even with south-facing windows.
Because of this, it makes a big difference to have an additional light source – simple fluorescent lights in approximately the 6000 Kelvin range, suspended 6 inches above the foliage. I leave them on for 12-14 hours a day.
In the video above, I just used one 24″ length light above one tray. In the photos on this page, you can see I have four 48″ lights above two trays, which gives more balanced light across the width of the trays.
If you’re sticking with just the original light source – the sun galloping across the winter sky – you’ll probably need to rotate your plants so they don’t incline in one direction towards the light.
Rotation is a bit unnatural for them, but it’s better than having them all permanently leaning like a dog with its head out the car window.
You’ll also benefit from supplemental heat when growing plants from seeds, especially those plants that originated in warmer climates like many of our annual vegetables, especially if your trays are sitting beside a cold window.
Soil temperature makes a huge difference for germination, so it can be worth spending a bit of money for a heat mat, but again, it’s not usually necessary.
It takes time for seeds to wake up once you plant them – anywhere from a couple of days to several weeks, depending on the species.
These organic fertilizers stimulate plant growth and health, and help them deal with stressors. The water activates germination.
After soaking and draining my seeds, I sprinkle some mycorrhizal fungi on them, except those from the cabbage and beet families because they don’t form a mycorrhizae relationship.
How To Plant Seeds
Before planting seeds indoors, water the soil without saturating it completely.
When I’m watering, I also use my effective microorganisms, liquid kelp and/or sea minerals.
Seeds should be planted about twice as deep as the diameter of the seed, whether in the garden or in a tray.
Planting 2 seeds per cell will give you a better chance of getting something growing in each cell, and allow you to cut out the weaker seedlings once you can see which ones are doing better.
A spray bottle helps to keep the soil moist until the plants come up. You want to keep it moist until after germination, when you can let it dry out a bit between waterings.
When your plants are almost ready to go outside, you can “harden them off” by bringing them outside for a few hours during the day, gradually upping their time in the open air over several days before you set them free in the big wild world of your garden.
Do you have any questions about starting plants from seeds? Let me know below.