How warm should it be to harden off plants?
Hardy plants can be hardened off when the outside temperature is consistently above 40° F. Half-Hardy plants may be hardened off at 45° F.
At what temperature do seedlings need to be covered?
When the temperature reaches around 28 degrees F for five consecutive hours, protect your plants by covering them with sheets, blankets, towels, cardboard, or a tarp. Cover the plants before dark to trap them in warm air and don’t allow the coverings to touch the foliage.
What factors do refer to hardening off of the seedlings?
How to Successfully Harden Off Seedlings
- Greater range of temperatures outside.
- Chill factor, moisture loss and buffeting of moving air.
- Greater variation in water supply due to the above factors which increase evaporation from plants outside.
- Direct strong sunlight which can scorch young tender leaves.
Can seedlings survive 40 degree weather?
Hardy vegetables tolerate cold temperatures the best—their seeds will germinate in cool soil, and seedlings can typically survive heavy frost. Plant these seeds or transplants two to three weeks before the date of the average last spring frost; they will grow in daytime temperatures as low as 40 degrees Fahrenheit.
How big should seedlings be before hardening off?
Day 0: Start hardening off seedlings when they’re a couple inches tall with their first set of true leaves. That’s right: the process of hardening off seedlings should start indoors first.
How do you harden seedlings in a cold frame?
To begin hardening off plants, place them into a shaded cold frame on a cloudy day for a few hours. Then, close the frame. Gradually, increase the amount of sunlight the transplants receive and how long the frame remains open each day.
When can I put my seedlings outside?
The general rule of thumb is that when a seedling has three to four true leaves, it’s large enough to plant out in the garden (after it has been hardened off). When you plant a seed, the first leaves to emerge are the cotyledons.
What temperature should a greenhouse be for seedlings?
A good aim is to keep the temperature inside the greenhouse between 7 – 21°C (45 – 70°F). The roof vents should provide the majority of the ventilation, with the side vents only being used once the outside air is warmer.
What temperature should a greenhouse be at night?
Generally, the ideal summer temperature for a greenhouse is 75-85° F during the day and 60-76° F at night. In the winter, this changes to 65-70° F in the day and 45° at night. The best way to control the temperature is through ventilation, shade cloth, and heating.