Here are the basics:
- You need a lightweight growing medium – for example, “Seed Starter Mix”
- Containers with drainage
- Plenty of good light
Notice I didn’t say dirt? Garden soil is not sterile and can harbor pathogens that can harm tender young sprouts. It is also heavy and dense, making it more difficult for the new seedling to grow and develop, and often, it does not drain well, leaving your seeds sitting in too much water. You want a growing medium that has light, fine particles that drain well. It’s not that you can’t use topsoil, you can. People have been doing just that for over 11,000 years. It’s just that it’s easier (if somewhat more expensive) to use a light-weight growing medium; especially if you are just getting started in starting your own plants from seed.
Seed-starting mediums usually contain a mix of ground pine bark, ground peat-moss, vermiculite, and/or perlite. You can make your own by mixing equal parts of these or you can buy commercial seed starter soil at a garden center.
One thing to be aware of with these type of growing mediums, once peat-moss completely dries out, it becomes harder to wet. Most commercial growing mixes that I’ve used are at least a little damp when you first open the bag, so there is no problem getting them to absorb water. However, when I come back months (or a year) later to use some more, it has dried out to the point that I need to get it moist again. I’ll put as much soil as I think I’ll need in a plastic tub and add a little water. Mix it well by hand and let it stand a bit to hydrate. If it doesn’t feel damp, add some more water and repeat.
Whatever container you use, it must have drainage. There are a variety of small containers that are used to start seed. Many are available at garden centers or big-box stores. Most common are small pots made of compressed peat-moss. Peat containers are usually not reusable. You plant the entire container and the plant’s roots will grow through the compressed peat into the surrounding soil. Because water can easily penetrate the compressed peat, it does not need additional drainage. This makes them easy to use, but, of course, they must be purchased. You decide if the ease of use is worth the cost.
I’ve also seen people use eggshells as containers. When ready to plant, you gently crush the eggshell and plant it whole; the shell provides calcium to the soil. Just remember that an eggshell does not have any drainage, so be careful not to over-water them. On the other hand, an eggshell doesn’t hold much soil, so be careful not to let it get too dry.
Many containers can be used to start seed. I’ve seen foam egg cartons used. Just poke a few holes in the bottom of each little cup to allow excess water to drain out. You could probably do the same with the containers that yogurt or sour cream come in. Almost any container can be used as long as you provide holes in the bottom for drainage so the seedlings don’t stand in water.
I’ve bought plants at garden centers that come in what are called cell-packs. The plants come 4-6 per pack. After removing the plants from the cell-pack, you can fill it with a light potting soil and reuse it to start your own seeds. The same can be true of the small 4″ or 6″ plastic pots that spring bedding plants come in.
Check the packet for planting instructions. Follow the packet’s directions for depth of planting. Once you are ready to set the plants in the ground, follow the packet’s guidance on how far apart to space the plants.
When planting, only plant 1-2 seeds per container – if the seed is fresh, you can probably get away with only planting one seed per pot. Even so, not all of them may come up. If the seeds are a year or two old, try 2 per pot. If they both sprout, you can snip off one of them leaving the stronger to grow.
You need to have pretty good light to start seedlings. Otherwise they will grow thin and stretched and may be too weak to stand up to the climate outdoors. You want to give your seedlings as much light as you can. A south-facing window is best since it can get direct sunlight all day. Unfortunately, I don’t have that. What I do have is a window that faces east and gets about 5-6 hours of sunlight. This works pretty well, but the seedlings still stretch a little.
Bottom heat – I once used a heating pad spread out across the top of a cabinet in front of a east-facing window. I set a towel on top of it and a tray to catch any water. I put my containers with seeds in the tray and turned the heating pad to its lowest setting. The gentle bottom heat helped the seeds to sprout faster than before. However, when using bottom heat, the soil will also dry faster, so keep an eye on it.
Transplanting – the first pair of leaves that the seedlings produce are the cotyledons or seed leaves. After that, the seedlings begin to produce true leaves. Once the seedling has produced 2-4 true leaves, it is ready to transplant.
Hardening-off – If you have been growing your seedlings indoors, they will need to be hardened-off before being transplanted outdoors. Here’s an article that does a good job of explaining it.
Starting Seed Outdoors
This year, I planted a variety of zucchini called Astia. It is compact enough to be grown in a medium-to-large pot, so I planted two seeds in the center of the pot. (Two, in case one didn’t sprout. However, if both sprout, the weaker one must be snipped out to allow the stronger to grow.)
For vegetables, this usually means in full sun. However, if you are growing in less than perfect conditions (as most of us are), try to find a spot that gets at lease six hours of direct sunlight. Fortunately, the front of my condo just barely gets six hours.
The more light, the better. Vegetables that set fruit (tomatoes, peppers, etc) can manage to grow in the six hours range. They will not be the full, bushy plants that full sun all day will produce, but you can get fruit from them. See my previous post, Growing in Less Than Full Sun for more information.
So, if you only use a few seeds out of a pack, can you keep the rest until next year? The short answer is yes, but…
The percentage of seeds from a packet that will sprout is known as the germination rate. For a newly-purchased packet of seed that was packaged for the current year, the germination rate is probably between 95-100%. However, each year after that, the germination rate will decline. This means that it may not be worth it to keep seeds longer than a couple of years.