Tag Archives: seedlings

Toughening up those Seedlings

This week we noticed our little seedlings in the greenhouse are ready to make it out into the great outdoors!  Also, in some of our raised beds where we used scattering seeds as a method of distributing plants, some of the seedlings are becoming a little crowded. Below is a little information on handling these garden topics.


Transplanting  Seedlings
Seeds that are planted too close together need to be thinned out once seedlings get their true leaves, or the 2nd set of leaves. First, thoroughly water the plants. To separate the seedlings use a stick (a pointed stick works well) to push into the ground next to the plant and pry the soil up gently. The most delicate part of a seedling is the stem so use gentle hands or hold onto a leaf. Re-plant seedlings in a new, spacious area. Plant no deeper than where the original soil line was. Water gently and thoroughly.


Hardening off Seedlings
Direct sun exposure, cold nights and wind can damage or kill tender seedlings that have been started indoors or in a greenhouse. Young plants should be introduced gradually to the outdoor environment. This can be done in a couple of different ways. The following information on hardening off is from Norma Rossel, Quality Assurance Manager for Johnny’s Selected Seeds:

• On a mild day, start with 2-3 hours of sun in a sheltered location.
• Protect seedlings from strong sun, wind, hard rain and cool temperatures.
• Increase exposure to sunlight a few additional hours at a time, but do not allow seedlings to wilt.
• Keep an eye on the weather and listen to the low temperature prediction. If temperatures below the crop’s minimum are forecast, bring the plants back into the greenhouse or cover with a cold frame.
• Know the relative hardiness of various crops. Onions and brassicas (i.e. cabbage, broccoli, etc.) are hardy and can take temperatures in the 40’s. After they are well hardened off, light frosts won’t hurt them. Warm-season crops such as eggplants, melons and cukes prefer warm nights, at least 60° F. They can’t stand below-freezing temperatures, even after hardening off
• Gradually increase exposure over a 7 to 10 day period.

From Growing Gardens Website:
Recommended Minimum Temperatures (for seedlings)
40° F.
Broccoli, Brussels sprouts, kohlrabi, cabbage, onions, leeks, parsley

45° F.
Celery, Chinese cabbage, lettuce, endive

50° F.
Squash, pumpkin, sweet corn

60° F.
Cucumber, muskmelon

65° F.
Basil, tomatoes, peppers


In the lower beds, I have gone through and spaced out most of the collards and mustards that were clustered together. In the next week, I see that hardening off (and planting) the rest of our greenhouse seedings is a priority, so Axcelle and I are leaving the greenhouse front flap open. It’s getting hot in that hothouse!

Happy gardening and last week of classes!


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