Hardening off seedlings

Helping tiny plants survive our Prairie winds

Tender seedlings like vegetables and annuals purchased from a greenhouse need help to transition from a hot, humid and pampered environment to the great outdoors.  Here are some tips:

  • place your seedlings in a sheltered spot, out of direct sunlight & wind
  • give them an hour outside on the first day and increase by an hour every day after that
  • plants dry out much faster outdoors so check your seedlings often; keep them evenly moist but don’t let them sit in water
  • it’s easier to move seedlings in a tray or shallow box
  • store your seedlings in a shed or garage at night – you don’t need to bring them in the house
  • if your seedlings turn yellow, it may mean they are not getting enough sunlight
  • depending on weather, it can take 7 – 10 days for your seedlings to get used to sunshine, fluctuating temperatures, low humidity and wind
  • when there is no risk of frost and the soil temperature is warm, you’re ready to plant!

The hardening off process is the best advice but doesn't work for everyone's personality. Some of us are really great at buying plants but run out of ambition to plant them at some point through the hardening off phase. Is there a way you can get away with planting them the same day you buy them? Yes, there is! If you're going to try the direct planting method, it's really important to buy your seedlings from a quality greenhouse that doesn't pamper their seedlings too much.  They should look pretty hardy with a generally firm stem and not too leggy. Plant your seedling directly into the soil where you intend to keep it and water it in well. From here you have two options:

  1. The coffee tin method - If you happen to have a bunch of large coffee or tomato juice tins, you can simply cut the top and bottom off of them with a can opener and place one around each newly planted seedling. After a couple of weeks, remove the tins and save them until next year.
  2. The milk jug method - Remove the lid from a plastic 4L milk jug. You won't need the lid again so toss it in your recycling bin. Cut the bottom off of the jug.  Place the milk jug on top of the seedling as a mini-greenhouse, burying it slightly so it doesn't blow away. If you're in a windier location, you may need to tie something to the handle of the jug to weigh it down. Keep the plant covered the first day. Remove the milk jug greenhouse for a few hours the next morning but make sure to remember to put it back on your plant before it gets too hot. Continue to do this for several days, gradually increasing the time your seedling is outside of its milk-jug greenhouse. By the end of the week, your plant should have adapted enough to survive without assistance.
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