Seed Starting Pt. 3 – Seeding In

Once you have a place to start your seeds you of course will need a growing medium and some type of container to put them in. Containers of all kinds are available, and just about anything can be used from milk cartons to egg cartons to purpose-made seeding flats as long as they meet a few criteria. They must be deep enough and sturdy enough to hold 2-3” of growing medium, they must be able to hold up to being wet, and they must provide adequate drainage. I use commercially made plastic seed flats as they are inexpensive, a convenient size, and easy to use and keep clean. Another option is peat pots, which can hold the plant until it’s ready to be set out, eliminating the need for intermediate transplanting, but they aren’t as flexible as using flats and can get costly for large numbers of plants.

It’s important that your containers be clean and free of any contaminants that may spread soil-born diseases to your seedlings. Every spring I wash out my flats and packs in soap and water with a little bleach added to disinfect them. It’s a tedious job, but contributes to a healthy environment for your plants. And by reusing as many of the containers as possible you’re keeping some of the plastic out of the waste stream, so collect those plastic 4 packs your neighbors that garden throw out every year.

The flats I use are paired with a perforated flat nested into a solid-bottomed flat. This provides excellent drainage and contains any water that may drip through the perforated flat. I line the perfed flat with paper towels to keep the soil mix from washing through the holes, making sure none of the paper sticks up above the soil line.

I then fill the flats to about ½” from the top with a soiless seed starting mix, firming well, especially around the edges of the flats. I’ve found these types of mixes to be far preferable to garden or potting soil to start seeds. They are sterile, so they will not spread pathogens to your plants, hold water well, drain well, and have a light body which makes it easy for the seeds to sprout through. If you use plain dirt, you should lighten the body with peat moss, perlite and/or vermeculite so the soil won’t clot and dry hard between waterings, but because of the chances of contamination I don’t recommend using garden soil. You can however sterilize small amounts of dirt by baking, or saturating with boiling water. If your soil mix is quite dry you should water it thoroughly and allow it to drain completely after filling your containers. This will settle it in and prevent dry pockets that can keep seeds from germinating.

Once your containers are ready, it’s time to decide what to put into them. First, read the info on your seed packets carefully. You need to know the recommended planting depth and temperature range the seeds prefer, and how long before setting your plants out you should be starting them. You should group your plantings accordingly, planting seeds that prefer warmer temps such as tomatoes and peppers together, and seeds that like it a little cooler such as broccoli and lettuce in separate containers. I generally start my seeds about 8 weeks before I’m planning on putting them into the garden and flower beds. In my part of the country, you’re better off waiting until Memorial day to transplant warm weather crops such as tomatoes and eggplant. Keep in mind that it’s the soil temperature that’s important – if you plant warm weather crops in cold soil they’ll just sit there and sulk until the ground warms up. I believe that starting your plants too early does more harm than starting them a little late as it’s difficult to give larger plants optimal growing conditions indoors, and smaller plants will quickly come up to size when planted at the right time, so resist the temptation to jump the gun on getting seeds started.

I’ll put 8 evenly spaced rows of seeds in a flat. I always start some extra plants in case of problems and give away what I don’t use, which is why I start an entire flat of tomatoes. Using a marker stake I make a furrow in the flat to the correct depth for the seeds I’m planting. I then place seeds evenly in the furrow, in the case of tomatoes, 10-12 seeds per row. The rows will be thinned later if necessary after the seeds have sprouted. Fresh seed under optimal conditions will have high germination rates so take the age of your seed in consideration when deciding how close to plant the seeds, you may want to sow a little heavier if your seed is old. Lightly press the seeds into the soil, cover and firm well. Be sure to label your rows or containers and/or make a seeding map to keep track of what is planted where.

Once your container is planted, thoroughly and gently water it. Seeding mixes are often very light weight so be careful not to wash out your seeds. Now your containers are ready to go into your plant rack.

When I first put my flats into my rack I have just the bottom tier lights on constantly to warm the rack and provide a couple of warm spots on the upper shelf for bottom heat. I position the tomato and pepper flats over those warm places as they like it and will germinate faster than if no bottom heat is used. Put at least a couple of thermometers in various places to keep track of temperature and to show you variations in different parts of your growing space and place your containers according to the seed’s preference for cooler or warmer temps.

Check your plants every day, and don’t water your containers until the soil on top is starting to dry out. More plants have been killed by overwatering than underwatering; too much moisture promotes mold and “damping off”, a fungal infection that kills seedings. Soon you’ll be rewarded by the appearance of little green shoots. At that time I start to cycle the fluorescent lights in the upper section. I give my plants about 14-15 hours of light per day. Keep the lights as close to the tops of the young plants as possible without touching them and adjust the height regularly. Some seeds are slower and more sporadic when germinating so be patient and don’t give up on your seeds too quickly. As the rows fill in, thin your plants to about 1 to 1 ½” apart. Do this after watering so the roots slip out easily and don’t disturb the neighboring seedlings when pulled.

After all your containers have germinated you will no longer need the bottom heat if you’re using it. It’s a good idea at this time to lower the temperature a bit in your rack if possible as it promotes sturdier growth. Some elaborate setups include small fans to gently jostle the plants which is supposed to toughen them. I start using a water-soluble fertilizer at this point, mixing a mild solution applied with every watering. Soon, true leaves will start to emerge from your plants and when the second set starts to show, it’s time for transplanting into individual packs.

So what plants do I start? Lots of tomatoes: Wayahead, Roma, Carmello (a French main crop variety), Celebrity, Opalka (a favorite paste type of mine) and Sweet 1,000,000 (Cherry). Peppers: Ancho, Kolaska Paprika, Sunbright (a gold bell), Fat ‘n Sassy (a green bell), and Cayenne. Broccoli, Brussels Sprouts, Zucchini, Cucumbers (the long, English type), Lettuce (Grand Rapids leaf and Buttercrunch), Parsley (Moss Curled and Italian Flat Leaf), Basil, Thyme, and Marjoram. For color I have Annual Flax, Violas, Zinnias, Cosmos (Sensation and Sunny), miniature singlet Marigolds, Globe Amaranth, Shasta Daisies, and 2 types of Morning Glories.

In addition I direct seed other veggies and flowers as well as purchase a couple of flats of Impatiens every year. As you can probably tell, I like spending a lot of time outdoors!