A request has come across my desk, well across my Facebook, to write an article on how to start seeds. When I reflect on my first gardening attempts at growing my first plants from seed, and I remember my colossal failures, I find this to be a good question.
Seeds need time. Well actually, plants need time. Seed descriptions tell how many days it takes from seed germination to plant maturity. For example, the average tomato plant takes 90 to 100 days to reach maturity. This means that a gardener can't wait till July (in this agricultural zone) to put a tomato seed in the ground because the plant won't have time to mature before first frost. So the gardener, as with the tomato, needs to give the plant at least three months from germination for the plant to bear edible fruit. Germination can take ten days to two weeks. That means if one wants tomatoes in July (weather permitting), seeds need to be started in March (for agricultural zone 7). Celery takes longer to reach maturity, so it needs to be started earlier. Cool weather crops like broccoli and cabbage need to be started very early so to be planted outdoors when weather is still cool.
First things first, you, the gardener, need to identify your agricultural zone and count backward. You need to be aware as to when your last frost date is so you know when tender annual crops can physically go into the ground without fear of being killed by cold temperatures. Plants are generally six to eight weeks old when sown. Technically, Knoxville is zone 6B. We can expect our last frost to be around April 20th, but Mother Nature sometimes has her own watch. It is best to keep an eye on the weather to determine the best time to plant your beautiful plants in the garden.
There are two methods for starting seeds: direct and indirect. Direct sowing of seeds means the seed is directly planted into the ground. Indirect sowing means the gardener begins growing the seed in a container. The latter is usually done because some plants (like tomatoes) need to be started while air and soil temps are still too cold for a young seedling and plant to survive without protection in the garden.
Some seeds are better started as a direct sow into the ground, mainly because they don't transfer well or it is just easier (like with large seeds). Early spring crops like carrots, radish, beets, peas, lettuces, greens are best sown directly, some as early as mid-March. If you live in an agricultural zone that warms the soil in time to allow your plants plenty of time to germinate and grow to food bearing size, sow directly as with summer and winter squashes, cucumber, okra, melons and beans after last frost usually in May.
When planting seeds, both directly and indirectly, seed depth is important. Rule of thumb is to plant seeds according to size. For example, a large seed like a squash seed can be planted about an inch deep, but tiny seeds like basil, celery, and carrot should only be planted about ¼ an inch deep. The bigger the seed, the deeper it can be planted. When direct sowing seeds, spacing is important, too. Usually, the seed package will tell how far apart to plant seeds and whether or not thinning is necessary.
There are tricks to sowing some plants outdoors, like carrots. Carrot seed is very fine and easily falls too deep in the soil, and the sun's rays can't penetrate it. Some people plant carrot seeds in a sand layer on the natural bed. Dampen the sand and make the rows (not too deep) and sprinkle the seed in the row. Add radish seed to the row and pinch the soil closed over the seed. Carrot seed takes a long time to germinate. Radish seed germinates quickly and marks the row. Radish loosens the soil and makes it easier for carrots to grow. By the time the radish is mature and picked, the carrots are growing strong. It is a perfect combination.
Plants that benefit from indirect sowing of seeds are tomatoes, peppers, herbs, celery, broccoli, cabbage, eggplant and most flowers. Keep these things in mind when direct sowing:
Soil. The best thing you can do is buy (or create a peat mix of your own) that is light and loamy. I go down to Knox Seed on Rutledge Pike and buy the big block of Pro-Mix for like $25 bucks. It is a huge block of shrink-rapped soil. The bag might weigh 25lbs. It is definitely cumbersome. They sell it in smaller bags, but somehow, I always put to use that big block through out the season. The reason that light loamy soil is so important is because the seeds need to be able to penetrate that top layer. If the soil is too heavy, no light gets through and, well, it's like trying to push off a big heavy cinderblock. You can go to most home centers and buy seed starting trays, which I have even at Kmart. This may be the way to go for first timers.
Temperature and protection from the elements. Seeds ideally germinate when soil is kept warm and the air relatively humid. Ideally, I think (at the top of my head) that the perfect temp is between 68 and 72 degrees. This is the tricky part if you don't have access to a heated greenhouse. The seeds need to be in a sunny area and kept warm. A sunny warm window inside your home might be enough. R.H. Shumway's seed catalog has warming mats that you can buy to keep the soil at the perfect temperature for germination. You may find a local store that carries them too. I have never used one of these, but I may need to consider one this year. You also want to keep the environment rather humid, but not too wet and soggy.
Containers. What you start your seeds in is an important thing. Initial containers shouldn't be huge and deep. What I found the easiest to use is a flat. A flat is a long, but not deep, rectangular plastic thingy. Usually if you buy six six-packs of flowers, they come in a handy carrying tray called a flat. Use a flat that is mostly plastic with a few holes on the bottom, not the very "holey" kind that is a glorified mesh sort of thing. You will also need larger containers that drain well to transfer seedlings. I save containers from plants I have purchased. I recycle quart milk cartons by cutting them in half and poking holes in the bottom. Orange juice and yogurt containers work well, too. Soup or vegetable cans don't work well because it is hard to get the plant out. You need something that is rather malleable. I have become a fan of peat pots which are cheap and can be planted directly into the soil. I have friends who make their own pots from newspaper.
Seeds. Remember to use heirloom, not hybrid or GMO. (For more info on this read Heirloom vs. the Other Stuff ). Get your seeds from a reputable company or friend. Due to margin of error, you will want to start more seeds then plants you intend to actually put in the ground. Seeds only have a certain % germination rate, so you have to start more than you actually want. For example, I may only want three tomato plants (trust me, three plants produce way more tomatoes than our little family can possible eat), but I start at least a dozen seeds. Like photography, it may take many shots to get that one good picture.
Method is simple. Take the flat and place it in front of you so the long side faces you. Fill it with slightly dampened, but not soggy wet, soil. Don't pack the soil, but lightly press it to minimize air pockets. Use a pencil or a thin stick to press six rows into the soil keeping seed depth in mind. Lay the seed into the row. How much seed depends on how much you want to thin or transfer. With tomato seed, I usually do about ten seeds per row of the same variety with the hopes of ending up with several strong seedlings to transfer. Don't mix seeds in the rows, not even several different types of tomato. When they begin to germinate, you will not know what is what. It is better to start more trays and make extra rows. After you lay the seed in the row, either pinch the soil over the seeds or simply sprinkle more prepared soil over the row to cover the seed. Label the row telling what is planted and the date it was planted. Water the seeds mimicking a soft rain being careful not to disrupt the soil.
When seedlings appear, anywhere from 6 to 14 days, keep them protected from the elements. When seedlings are about two inches tall and before the roots begin to entangle, transfer each seedling to its own container, making sure the container isn't too big. Saved six-pack containers (like what pansies come in) work well. Fill the container with the same type of dampened soil used to start the plants. Lightly press the soil, but don't pack it. Make a little hole that is deep enough for the roots. Usually, I plunge my pinky or pointer finger about second knuckle deep into the soil. Use your finger and carefully scoop out a seedling and transfer it to the new container. Plant the seedling a little deeper than it was growing, but not too deep. Gently push the soil around the seedling. Water and label the containers.
Plants usually outgrow the six-pack container and need to be transferred once more into a larger container. Tomato plants seem to benefit greatly from a double transfer. Especially with tomato plants, plant the plant a little deeper than it was originally growing in the pot.
It usually takes six to eight weeks for seedlings to grow large enough to sow into the ground. It is important, though, to keep a watchful eye on the weather. I recommend waiting at least a week after your areas last frost date. You will also need to harden plants off. This means exposing the plants to the outdoors and the elements about a week before you plant them outdoors. On nice days, simply put the plants outside and bring them in at night (or return to greenhouse) so they can used to living outside.
One alert. When reading seed catalogs, you will see all kinds of cool gizmos that (are supposed to) make planting seeds or gardening easier. I can't account for all of them, but I am thinking particularly of a device that helps dispense seeds to the soil. Don't buy it. Take your $4 and buy more seeds.
Hope this article helps. As usual, if you have any comments, additions or questions, they are welcome.
Thanks for reading.