Seed Starting
This article on Seed Starting was adapted from an article originally published in Punk Planet in March/April 2003.
Birth of a Seed
Picture a seed buried in dirt beginning to split open. Suddenly, a tiny white stem with a bulbous green top tears free and starts to uncurl. It pushes its way to the surface of the dirt, and in a hazy series of flashes, it unfolds into the smallest, most delicate plant. Fast forward to lush greens, plump tomatoes, sweet smelling basil, a happy gardener bringing forth delicious food from rich earth.
This is gardening at its dawning, at its roots, literally. No matter where you place yourself as a gardener—experienced or a first timer—seed starting is a fascinating and economical way to begin. Starting your own seeds opens you up to more varieties of plants, gives you earlier harvests, healthier and stronger plants, saves you money, and provides you with personal satisfaction.
Materials
To start seeds, you need to begin with some materials.
Once you have your seeds (see Where To Get Seeds), you need to decide on containers. Any container—yogurt containers, plastic cups, egg cartons, cardboard boxes, newspaper pots—will suffice, as long as it is at least 1-2” wide and 2-3” deep. Simply poke a hole in the bottom of the container for drainage and wash the container thoroughly—hot soapy water, followed by a rinse of bleach and water, or white vinegar and water—to avoid contamination. You can also use commercially manufactured seed starting cell packs or peat pots.
I like to use soil blocks to start seeds. First, they are less expensive than containers. Two, they are based on a concept of using air as walls. A typical growing medium has solid walls, which the roots eventually grow against. If not transplanted quickly, the roots will wrap themselves around the mix in the container endlessly, making them less healthy and more difficult to plant in the garden. In a soil block, however, roots will grow to the edge of the soil and encounter nothing but air. The roots don’t want to be exposed, so they stop growing at the edge of the soil block and wait to be transplanted. Third, a soil block is not soil-less like the typical seed starting mix, but consists of elements found in a garden: soil, compost, peat (partially decayed plant residue from bogs), sand (used to promote aeration), greensand (also called glauconite, this gives the soil micronutrients), colloidal phosphate (a clay material which enriches the soil), lime (used to adjust the pH of the mix), perlite (sometimes used instead of sand) and natural fertilizers. You need not fertilize or otherwise manipulate the soil block once the seedling has emerged because the block has everything it needs. The fibrous qualities of the peat and compost retain water far more efficiently than a soil-less mix, and transplanting in the garden is simply a matter of digging a hole, easier than extracting a seedling from its container.
The other way to go is to use a seed starting mix. Commercially prepared seed starting mixtures usually contain a blend of vermiculite (a mineral resembling mica), perlite (a white mineral foam formed from volcanic glass) and peat. As you can see, there is no soil in the mix. Soil-less mix is often preferred for seed starting because it is sterile, lightweight and inexpensive. Seedlings do grow well in this mixture but will need to be treated with liquid fertilizers (fish emulsion or seaweed fertilizer) later on in the growing process.
Light and Heat
Now you need just two more elements to get started: light and heat. The light source in your home is unlikely to be of the strength and consistency which seedlings require, especially if you’re starting in late winter. While there are numerous seed starting light kits available, inexpensive fluorescent lights work perfectly well. Before your seeds germinate, you won’t need the lights, but once the true leaves appear (more later), your seedlings will need direct light not more than 2” above them for 12-16 hours a day. The easiest way to do this is to stack or suspend your lights so they can be gradually raised as the seedlings grow.
Most germinating seeds need heat and do best at around 70˚F. While you can buy heating pads and boxes specifically designed to warm your seeds, I simply place my seedlings on trays on top of, or close to, the radiator. If you don’t have radiators, try the top of the refrigerator, or the warmest room in your place. Once the seeds germinate, they no longer need heat, so this is a short-term issue.
When to Start
Most seed packages list the span of days from germination to maturity. Work backwards from that. First you need to determine your region’s frost free date.
When you’ve worked out the particulars, plant away. This is probably a good time to put your containers on a tray. (I use a plastic cafeteria tray. If you use a metal tray like a cookie sheet, be sure to line it with plastic so it doesn’t rust.) Then, in a bucket or a large bowl, water your seed starting mix. Packages will provide directions, but generally, you want your seed starting medium to be thoroughly wet, but not muddy. A little practice with a small amount of mix will make this simple enough. Fill your clean container with the wet mix, poke a small hole in the mix with the clean tip of an eraser, and drop your seed in, one or two per container. Most seeds—contrary to popular package directions—only want to be submerged about three times their thickness and want to be lightly covered with either a bit more of the mix, or with sphagnum peat moss (about $5/bag), which will help retain moisture and is a natural fungicide. After your seeds are planted, water the tops of the containers with the gentle setting on your spray bottle. If you’ve bought containers with clear plastic covers, put those on top to contain the humidity. Otherwise, cover the containers with plastic wrap or glass. Lay the trays on your heat source and wait.
Soil Blocks
I found a soil block maker online for about $25, but a friend built one for me out of wood (materials, about $3, time about 45 minutes). I learned that for a small scale, urban gardener, I needed only compost ($5/bag), brown peat ($5/bag), colloidal phosphate ($3/box) and greensand ($3/box), all of which I bought at a local gardening store. I mixed these in the proportions of 16 parts peat/4 parts compost/1/4 part greensand/1/4 part colloidal phosphate, with a lot more water than I would have with a soil-less mix. Not only will this mix hold far more water, it actually needs more water in order to maintain its form and strength. Coleman recommends using 1 part water to 3 parts mix, until the whole mixture feels like paste. Using my 2” square wood block maker (simply four 2” squares of wood screwed together, sanded lightly and finished with salad oil finish), I formed blocks of the mix and laid them on my plastic cafeteria trays. Then I poked holes in the tops of the blocks, dropped in my seeds, watered them very well, and covered them with plastic.
Germination
Germination, depending on the type and condition of the seeds, can take as little as 3 days and as long as 2-3 weeks. The first thing to appear will be a set of false leaves. Looking into your mix, you can sometimes see the uncurling of the tiny plant from its hardened shell, and the white tendrils of the stretching trunk turning green as it is exposed to light. This, to me, is the most exciting time of the process. Pushing up from the soil (or soil-less mix), the seeds are lifted from dormancy and are transformed into plants anxious to grow, flower and fruit. And once they’ve sprouted, it’s time to turn on the lights and remove them from the heat. This gets a little tricky, as different seeds will sprout at different times. This is where your popsicle sticks come in (labeling sticks from a garden store, $4 for 100). Since you may move your seedlings around, it’s crucial to be able to identify them. I simply write the name of the plant on the stick and push it into the dirt or soil block. You also may need to separate your plants to put some under light while others are still germinating. If you’re using separate containers, this is easy enough. If you’re using store-bought plastic cell pack trays, you can cut these apart with a scissor. Remember to put the lights not more than 2” above the plants and leave them on for 12-16 hours per day.Important! Once you’ve placed the lights over the seedlings, you should remove the plastic covering.
The first leaves that appear are round and are called cotyledon leaves. Within a few days, a second set of leaves, larger and more defined than the first, will appear. These are the plant’s true leaves. Now you are ready to add fertilizer, if you’re using the container method. Since they’re so small, a half strength mixture of liquid fertilizer and water will do. Just spray it on with your spray bottle. If you can spray onto the soil or mix rather than on the leaves, this is better for the plant. (This is also true for watering—getting the water as directly as possible to the roots is best for the plant.) For the next few weeks, as your frost free date approaches, you simply need to take care of your plants. Keep them moist and keep them in light. If you’re using soil blocks, it becomes a little challenging to keep them wet. The best method I found was to pour water directly onto the trays. The soil blocks soak up only what they need.
Transplanting
If you’re using small containers, you may have to transplant after a few weeks. It’s hard to tell when a plant needs to be transplanted, but if you sense that the seedling is becoming too large for its container, it probably is. Some signs of this is that the plant is leggy (too long between sets of its leaves) or that plants are beginning to grow together. To transplant, use larger containers and repeat the process of planting. Fill the clean containers with your wet mix, dig a little hole in the middle and insert your whole seedling, including its mix.
The environment outside, of course, is very different than your home. These seedlings have never experienced real sun, real wind, real rain, insects or predators. It is your job to get them ready. Don’t be afraid of touching your seedlings. Gently tickling the leaves will make the stems stronger. As you get closer to transplant time, you’ll want to ruffle them even more often. They’re very fragile, but they need to be toughened up before they go outside. About a week to ten days before you’re going to transplant, on a moderate day, bring your plants outside for a couple of hours. Do this a little more each day, until a day or two before transplanting, when you should leave them out overnight.
On a day with not much wind but plenty of sun, bring your plants to their final destination. Whether you’re planting in the ground or in pots, prepare your area. If you’ve used soil blocks, simply dig a hole and cover them up. If you’ve used containers, you must be a little more careful. The best way is to turn the container sideways so the plant and the soil or mix slide out from the container. If you must handle the plant, it is better to grasp the roots or the leaves rather than the stems. If your plants are root-bound, you’ll have to cut into the roots with a sharp knife in order to stimulate them into growing into the new soil. If you have transplanted from the original seed starting container to a larger pot, this probably won’t be necessary.
Once the plants are in the dirt, water them well to help them establish their roots, and you’re finished. Congratulations. You’ve gone from seed to plant.
Birth of a Seed
Picture a seed buried in dirt beginning to split open. Suddenly, a tiny white stem with a bulbous green top tears free and starts to uncurl. It pushes its way to the surface of the dirt, and in a hazy series of flashes, it unfolds into the smallest, most delicate plant. Fast forward to lush greens, plump tomatoes, sweet smelling basil, a happy gardener bringing forth delicious food from rich earth.
This is gardening at its dawning, at its roots, literally. No matter where you place yourself as a gardener—experienced or a first timer—seed starting is a fascinating and economical way to begin. Starting your own seeds opens you up to more varieties of plants, gives you earlier harvests, healthier and stronger plants, saves you money, and provides you with personal satisfaction.
Materials
To start seeds, you need to begin with some materials.
- Seeds
- Containers in which they will grow
- Dirt and compost or seed-starting mix
- Trays to catch the water underneath your containers
- Lights
- A watering method (usually a spray bottle)
- Popsicle sticks (to label your seedlings)
- Liquid fertilizer (seaweed or fish emulsion is best).
Once you have your seeds (see Where To Get Seeds), you need to decide on containers. Any container—yogurt containers, plastic cups, egg cartons, cardboard boxes, newspaper pots—will suffice, as long as it is at least 1-2” wide and 2-3” deep. Simply poke a hole in the bottom of the container for drainage and wash the container thoroughly—hot soapy water, followed by a rinse of bleach and water, or white vinegar and water—to avoid contamination. You can also use commercially manufactured seed starting cell packs or peat pots.
I like to use soil blocks to start seeds. First, they are less expensive than containers. Two, they are based on a concept of using air as walls. A typical growing medium has solid walls, which the roots eventually grow against. If not transplanted quickly, the roots will wrap themselves around the mix in the container endlessly, making them less healthy and more difficult to plant in the garden. In a soil block, however, roots will grow to the edge of the soil and encounter nothing but air. The roots don’t want to be exposed, so they stop growing at the edge of the soil block and wait to be transplanted. Third, a soil block is not soil-less like the typical seed starting mix, but consists of elements found in a garden: soil, compost, peat (partially decayed plant residue from bogs), sand (used to promote aeration), greensand (also called glauconite, this gives the soil micronutrients), colloidal phosphate (a clay material which enriches the soil), lime (used to adjust the pH of the mix), perlite (sometimes used instead of sand) and natural fertilizers. You need not fertilize or otherwise manipulate the soil block once the seedling has emerged because the block has everything it needs. The fibrous qualities of the peat and compost retain water far more efficiently than a soil-less mix, and transplanting in the garden is simply a matter of digging a hole, easier than extracting a seedling from its container.
The other way to go is to use a seed starting mix. Commercially prepared seed starting mixtures usually contain a blend of vermiculite (a mineral resembling mica), perlite (a white mineral foam formed from volcanic glass) and peat. As you can see, there is no soil in the mix. Soil-less mix is often preferred for seed starting because it is sterile, lightweight and inexpensive. Seedlings do grow well in this mixture but will need to be treated with liquid fertilizers (fish emulsion or seaweed fertilizer) later on in the growing process.
Light and Heat
Now you need just two more elements to get started: light and heat. The light source in your home is unlikely to be of the strength and consistency which seedlings require, especially if you’re starting in late winter. While there are numerous seed starting light kits available, inexpensive fluorescent lights work perfectly well. Before your seeds germinate, you won’t need the lights, but once the true leaves appear (more later), your seedlings will need direct light not more than 2” above them for 12-16 hours a day. The easiest way to do this is to stack or suspend your lights so they can be gradually raised as the seedlings grow.
Most germinating seeds need heat and do best at around 70˚F. While you can buy heating pads and boxes specifically designed to warm your seeds, I simply place my seedlings on trays on top of, or close to, the radiator. If you don’t have radiators, try the top of the refrigerator, or the warmest room in your place. Once the seeds germinate, they no longer need heat, so this is a short-term issue.
When to Start
Most seed packages list the span of days from germination to maturity. Work backwards from that. First you need to determine your region’s frost free date.
When you’ve worked out the particulars, plant away. This is probably a good time to put your containers on a tray. (I use a plastic cafeteria tray. If you use a metal tray like a cookie sheet, be sure to line it with plastic so it doesn’t rust.) Then, in a bucket or a large bowl, water your seed starting mix. Packages will provide directions, but generally, you want your seed starting medium to be thoroughly wet, but not muddy. A little practice with a small amount of mix will make this simple enough. Fill your clean container with the wet mix, poke a small hole in the mix with the clean tip of an eraser, and drop your seed in, one or two per container. Most seeds—contrary to popular package directions—only want to be submerged about three times their thickness and want to be lightly covered with either a bit more of the mix, or with sphagnum peat moss (about $5/bag), which will help retain moisture and is a natural fungicide. After your seeds are planted, water the tops of the containers with the gentle setting on your spray bottle. If you’ve bought containers with clear plastic covers, put those on top to contain the humidity. Otherwise, cover the containers with plastic wrap or glass. Lay the trays on your heat source and wait.
Soil Blocks
I found a soil block maker online for about $25, but a friend built one for me out of wood (materials, about $3, time about 45 minutes). I learned that for a small scale, urban gardener, I needed only compost ($5/bag), brown peat ($5/bag), colloidal phosphate ($3/box) and greensand ($3/box), all of which I bought at a local gardening store. I mixed these in the proportions of 16 parts peat/4 parts compost/1/4 part greensand/1/4 part colloidal phosphate, with a lot more water than I would have with a soil-less mix. Not only will this mix hold far more water, it actually needs more water in order to maintain its form and strength. Coleman recommends using 1 part water to 3 parts mix, until the whole mixture feels like paste. Using my 2” square wood block maker (simply four 2” squares of wood screwed together, sanded lightly and finished with salad oil finish), I formed blocks of the mix and laid them on my plastic cafeteria trays. Then I poked holes in the tops of the blocks, dropped in my seeds, watered them very well, and covered them with plastic.
Germination
Germination, depending on the type and condition of the seeds, can take as little as 3 days and as long as 2-3 weeks. The first thing to appear will be a set of false leaves. Looking into your mix, you can sometimes see the uncurling of the tiny plant from its hardened shell, and the white tendrils of the stretching trunk turning green as it is exposed to light. This, to me, is the most exciting time of the process. Pushing up from the soil (or soil-less mix), the seeds are lifted from dormancy and are transformed into plants anxious to grow, flower and fruit. And once they’ve sprouted, it’s time to turn on the lights and remove them from the heat. This gets a little tricky, as different seeds will sprout at different times. This is where your popsicle sticks come in (labeling sticks from a garden store, $4 for 100). Since you may move your seedlings around, it’s crucial to be able to identify them. I simply write the name of the plant on the stick and push it into the dirt or soil block. You also may need to separate your plants to put some under light while others are still germinating. If you’re using separate containers, this is easy enough. If you’re using store-bought plastic cell pack trays, you can cut these apart with a scissor. Remember to put the lights not more than 2” above the plants and leave them on for 12-16 hours per day.Important! Once you’ve placed the lights over the seedlings, you should remove the plastic covering.
The first leaves that appear are round and are called cotyledon leaves. Within a few days, a second set of leaves, larger and more defined than the first, will appear. These are the plant’s true leaves. Now you are ready to add fertilizer, if you’re using the container method. Since they’re so small, a half strength mixture of liquid fertilizer and water will do. Just spray it on with your spray bottle. If you can spray onto the soil or mix rather than on the leaves, this is better for the plant. (This is also true for watering—getting the water as directly as possible to the roots is best for the plant.) For the next few weeks, as your frost free date approaches, you simply need to take care of your plants. Keep them moist and keep them in light. If you’re using soil blocks, it becomes a little challenging to keep them wet. The best method I found was to pour water directly onto the trays. The soil blocks soak up only what they need.
Transplanting
If you’re using small containers, you may have to transplant after a few weeks. It’s hard to tell when a plant needs to be transplanted, but if you sense that the seedling is becoming too large for its container, it probably is. Some signs of this is that the plant is leggy (too long between sets of its leaves) or that plants are beginning to grow together. To transplant, use larger containers and repeat the process of planting. Fill the clean containers with your wet mix, dig a little hole in the middle and insert your whole seedling, including its mix.
The environment outside, of course, is very different than your home. These seedlings have never experienced real sun, real wind, real rain, insects or predators. It is your job to get them ready. Don’t be afraid of touching your seedlings. Gently tickling the leaves will make the stems stronger. As you get closer to transplant time, you’ll want to ruffle them even more often. They’re very fragile, but they need to be toughened up before they go outside. About a week to ten days before you’re going to transplant, on a moderate day, bring your plants outside for a couple of hours. Do this a little more each day, until a day or two before transplanting, when you should leave them out overnight.
On a day with not much wind but plenty of sun, bring your plants to their final destination. Whether you’re planting in the ground or in pots, prepare your area. If you’ve used soil blocks, simply dig a hole and cover them up. If you’ve used containers, you must be a little more careful. The best way is to turn the container sideways so the plant and the soil or mix slide out from the container. If you must handle the plant, it is better to grasp the roots or the leaves rather than the stems. If your plants are root-bound, you’ll have to cut into the roots with a sharp knife in order to stimulate them into growing into the new soil. If you have transplanted from the original seed starting container to a larger pot, this probably won’t be necessary.
Once the plants are in the dirt, water them well to help them establish their roots, and you’re finished. Congratulations. You’ve gone from seed to plant.
