What is Hardening Off ?
Hardening Off is the act of progressively acclimating an indoor plant to the outdoors before transplanting it outside. This gradual acclimatization to direct sunshine, wind, rain, and temperature variations is critical to preventing damage to your fragile plants.
What Happens if You Don’t Harden Off?
Worse case: you can kill the plant.
- The most pervasive issue is sunscald. Think of sunscald as ‘plant sunburn’. Plant leaves can be damaged by direct sunshine.
- Too severe temperature fluctuations can lead to plant dehydration and wreak havoc with cell walls. Cold overnight temperatures. especially frosts, are not the the friend of unacclimatized houseplants.
- Wind can tear leaves, pull flowers off their stems, break branches, and uproot shrubs and trees. Hibiscus is an excellent example of a plant susceptible to wind damage.
- Rain can wilt fragile plants, damage blossoms and flowers, wash away mulch, and erode soil.
Hardening Off Plants
All plants, including vegetable seedlings, perennials, and annuals, that have been grown indoors (at home, in a garden centre, or in a greenhouse), must be progressively acclimatized to the outside environment. On the first day, leave them outside in a covered place for an hour. Increase the duration of time and exposure to the sun each day for the next few days. Some plants can take up to a week or more. The plants will then be ready for planting in the garden.
Hardening Off Tomato Plants
What are the possibilities of another frost in your area? Even if there isn’t frost, the forecast lows to 40F or sub 10C are not good for tomatoes. And the ground might still be icy. Learn why planting your tomatoes too early might produce a setback for your plants rather than the jump start you’re looking for.
Bringing Houseplants Outdoors
Houseplants benefit from spending the summer outdoors, but don’t rush them. For many plants, wait until the overnight temperature no longer dips below 50°F or 10°C. While you wait, you may start exposing your plants to more light by shifting them from an east window to a south window. Harden them off when it’s warm enough for them to go outside. Place them in a safe, shady area for 10 to 14 days before transporting them to their final destination.