Monday, March 19, 2012

Edible Landscaping: Growing and Transplanting Seedlings

So you’ve started your seeds indoors to get a jump on spring, and like magic they are beginning to grow. Now you’ve got seedlings. The excitement of having grown your own starts for your vegetable garden can turn into panic if it is still too cold to plant them in the garden. Here are my tips and "how tos" for managing seedlings for your edible landscape.

What is too cold?

It’s still too early to plant warm season vegetables into your garden if:
1. Frost is still a possibility in your area (check for the last expected frost date).
2. Nighttime temperatures are still below 50° F.
3. The ground hasn’t warmed up enough.

Growing Your Seedlings

The young seedlings will grow fast indoors and if you don’t give them the right conditions they’ll become weak and spindly. If you plant them in this condition they’ll under-perform and it will be disappointing.
As I wrote in my How to Grow From Seeds post, to raise strong seedlings you need to meet three basic requirements in addition to moisture: light, nutrients and temperature.

Seedlings in my backyard cold frame
Once the seeds start to grow they'll need either direct sunlight, or exposure to lights indoors. Your options are to hang lights over the seedlings if they’re indoors (12 hours daily), or to move them outside into a cold frame in the sun. The cold frame works well if outside temperatures are at least 40° F. If nighttime temperatures are too cold, bring them back inside for the night.


Feed the young plants with liquid fertilizer.  I use an organic dry fertilizer mix, such as Dr. Earth.  Soak it overnight in water (read the directions- it will be about 1 cup dry fertilizer to a gallon of water). Then use the liquid half strength to feed your plants weekly, and put the solids into your garden bed. You can also use a cup of mature compost from your compost pile to make a compost tea. Put the compost into a piece of cheese cloth to make a big tea bag and soak it for about fours days before you use it. It may not be as nutrient-rich as the fertilizer mix, but it’s good for the seedlings (remember: fertilizer is not necessary until the leaves begin to grow).


Protect from frost and temperatures below 50° F for warm season vegetables. I germinate seeds indoors, then keep the seedlings out in my backyard cold frame. I remove the cold frame lids on sunny days so it doesn’t get too warm, and close it up at night. Warm season veggies include: tomatoes, beans, squash, cucumbers, peppers, and eggplant. Spinach, lettuce, chard, kale, peas broccoli and cauliflower,
are all cool season veggies and have some degree of resistance to frost and prefer cool temperatures.

Transplanting Seedlings Into Containers

If your seedlings are in a flat, or getting crowded in their containers, transplant them individually into six packs or small pots to give them a chance to develop a healthy root system while you wait for the season to warm up.

Handle the seedling carefully to avoid damaging the roots or stem

1. Plant seedlings into damp potting soil (it has good drainage). Alternatively, a friend of mine uses his own mature compost and this seems to work.
2. Make sure your seedlings are in damp soil before you transfer them to the new pots.
3. Handle the seedlings by the leaves- avoid damaging the delicate stem or roots. Gently tease apart tangled roots and plant immediately.
4. Water well after transplanting and begin using liquid fertilizer.

For small seedlings, make a hole in the potting soil with a chopstick then gently push the root inside

Last but not least, after growing your plants indoors remember to acclimate them first before you plant them into the garden. Do this by bringing them out during the day to expose them gradually to direct sunlight (in a protected porch or cold frame) then bring them back inside for the night for about a week. This is called “hardening off”. It toughens them up for the outdoors.

Newly potted seedlings with room to grow

Enjoy nurturing your seedlings and watching them grow. You'll have the pleasure of starting your edible garden with the vegetable varieties you really want instead of having to grow whatever is available. But best of all, you'll have the satisfaction of knowing you can grow your own food from start to finish.

Photos: Urban Artichoke

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