You’ve your seeds sprout, grow true leaves and get taller. In your controlled environment, your ind00r-started seedlings have enjoyed a relatively stress-free life, protected from the heat, cold, wind and rain. Without elemental exposure, your little seedlings lack the hardiness to be successfully transplanted; but you can change all that by starting the hardening-off process on your own.
Hardening off takes two weeks, and entails gradually exposing your tender seedlings to the elements until they can be transplanted and live outside comfortably.
Beginning the Process
Start the hardening-off process two weeks before the seed’s outside planting date, which is dependent on the hardiness of the plant and the last frost date in your area. Once you’ve determine the date, begin by setting your seeds outside for a couple hours during the day in an area that’s shielded form sun and wind. Direct sun is a definite no-no for young seedlings at this stage, because it will burn the tender leaves. Remember to bring your seedlings in at night. Over the following days, you may increase the time your plants go outside, but do so gradually.
Your Seedlings are Almost Ready
After a few days of gradual and protected outside exposure, you can step up your efforts a notch. Leave your plants out longer and put them in sunnier, cooler, and windier spots. Although some evidence suggests that tomatoes respond well to fertilization at this point, generally it’s not a good idea to feed or overwater your plants right now – remember, you’re trying to toughen them up!
After two weeks of increasing exposure, it’s time to plant them for good. Water the ground thoroughly, and dig a hole just a few inches deeper than the pot in which your seedlings are currently residing. Holding your seedling by the stem, place the seedling in the hole and cover it gently with soil. Once the hole is filled, create a depression around the rim of the plant where water can collect. Be sure to water frequently and to fertilize after this final step. If your weather turns nasty, you can protect your seeds with sun shields, wind blocks, or Gurney’s cold covers.