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Seed starting Tips & Techniques
Starting your own plants from seed is lots of fun and very rewarding. But the truth is that it can also be confusing and a little intimidating! Here are a few tips to help make sure your experience is a good one.
Seed starting in PaperPots
Because the seeds are fairly large, tomatoes are one of the easier seeds to start. These seedlings are growing in PaperPots. It’s easy to be seduced by photos in the seed catalogs — it happens to the best of us, especially in January. But what the catalogs don’t tell you is that some plants are much harder to start from seed than others. No matter how much seed starting experience you have, starting tomatoes is easier than starting primroses. This is because some seeds will germinate almost anywhere, while others have strict requirements for moisture, temperature, and light.
So if you’re new to seed starting, I recommend that you stick with some easy varieties such as tomatoes, zinnias, marigolds, and coleus. These seeds don’t have any special requirements in terms of light, moisture or pre-treatment. Most seed packets provide little if any information as to specific germination requirements. I am a big fan of Stokes Seeds in Buffalo, N.Y., because their seed packets are written for commercial growers and provide lots of useful details. When you’re growing a challenging type of plant, such as primroses, the information they provide is invaluable. If you plan to grow lots of flowers, consider picking up a copy of From Seed to Bloom, by Eileen Powell (Garden Way Publishing, 1995). It provides specific germination requirements, growth habit, time of bloom, and much more for more than 500 different kinds of flowers and herbs.
The APS-24, one of several seed starting options. Containers are a personal choice. Gardener’s Supply offers several different seed starting kits. How do you decide which kind to use? I recommend experimenting with several. Ultimately you’ll choose one kind over another based on things like how much room you have, how attentive you are with watering, what kinds of plants you’re starting, how long the plants will be in the containers, and how many transplants you’re growing.
Over the years I have settled on a few different seedstarting systems:
I start very tiny seeds (like snapdragons, violas, and oregano), and seeds that take a long time to germinate (like primroses and larkspur) in 4″ x 7″ peat flats. I sprinkle the seeds on the soil surface and cover with a sprinkling of soil (unless they require light to germinate). Then I put four to six peat flats into a standard 10″ x 20″ tray and cover the tray with a clear plastic lid to keep moisture levels constant. Once the seedlings have their second set of true leaves, I separate the individual plants and put them into their own growing cells. This system is quick (my own No. 1 priority) and really saves on space. I transplant only as many seedlings as I need, and there are no bare cells where seeds didn’t germinate.
I also use a standard plastic tray with a 36-cell insert and a clear plastic lid. One nice feature of this system is that you can separate the insert trays into six-packs. This makes it easy to share extra seedlings with friends. I use this system for annual flowers such as zinnias and marigolds.
I am also a big fan of PaperPort. For starting a large number of seedlings of one variety, they simply can’t be beat. I use the Large PaperPots for tomatoes, peppers, and eggplants (transplanting them from other smaller containers once the plants have their second set of true leaves). I use the Medium PaperPots for sowing annual flowers — especially varieties I’m growing in quantity for the cutting garden. The medium size pots also make a great second home for seedlings that I’ve started in the peat flats. PaperPots retain moisture very effectively, and in the medium size, you can grow 80 plants in about two square feet!
I’m always cramped for space, so I reserve the Accelerated Propagation System (APS) for special varieties that really benefit from extra TLC. I find that peppers, which can be finicky about moisture, always do well in the APS. I also use them for impatiens, asters, and parsley. And I usually start my tomatoes in an APS, then transplant them into Large PaperPots. If you’re new to seed starting, the APS is a pretty foolproof system.
After you’ve planted your seeds, I recommend that you cover the container with plastic wrap or a clear plastic lid. As soon as the sprouts have come up through the soil surface, be sure to remove the lid or plastic wrap so your seedlings get the maximum amount of light and plenty of good air circulation.
The right soil makes a difference
Regular garden soil or potting soil is too dense for the roots of tiny seedlings. A good seed starting mix will be a soilless mixture of sphagnum peat moss, vermiculite, and perlite. This blend will hold moisture, but also be light enough to provide air and wiggle room for the seedlings’ roots.
All soilless mixes should be thoroughly moistened before you put them into the flats or containers. Dump some of the mixes into an old dish pan, add warm water, and mix it around with your hands until the moisture content is that of a well-wrung sponge. Then fill your containers. Sow your seeds and gently press them into contact with the soil. You don’t want air pockets, but you also do not want to compress the medium any more than necessary. Water thoroughly with a gentle dribble so you don’t disturb the seeds. This initial watering is important to establish good contact between seed and soil.
Gardener’s Supply offers two soilless seed starting mediums. Professional Germinating Mix has the finest texture. It is my first choice for starting seeds and is a must for use in the APS system. Transplant Mix has a coarser texture and is best for larger seeds, such as cucumbers or sunflowers, or for transplanting tiny seedlings into larger cells or pots. These mixes contain some nutrients, but you’ll still need to fertilize your seedlings once they have their second set of true leaves. I use Plant Health Care for Seedlings, which contains both organic and readily-available inorganic nutrients. I alternate that with a seaweed fertilizer because I’m convinced it gives me sturdier, more stress-resistant transplants.