Wilting during hardening off


I live in the Bronte area of Oakville and have started a veggie garden. My plants have grown quite a bit under the grow light I have but I’m worried about this hardening process. I’ve watered on average every other day according to the miracle gro potting mix dryness. 2 days so I started the hardening process I real about online by going 1hr on day 1, 2hr on day 2…etc incrementing by 1hr every day.

The first day i put them on the deck and placed a 4×4 plastic greenhouse thing we have that has a raisable roof as the wind was strong. After 30 minutes I checked on them and every leaf on every plant was completely wilted and couldn’t hold themselves up at all. I brought them in after 45mins total. Yesterday was very cloudy and they did not wilt nearly as bad and were out there for 2hours.

Day 3, today has been raining and on/off sun (15min bursts). I left them there for maybe 2.5hrs. Every time the sun came out the leaves fell completely wilted again pretty hard.

I’m a little worried going for too long would burn things badly. I do see some leaves have brown and yellow spots around the edges that have only appeared since yesterday.

Cucumbers, zucchini, tomato, a couple lettuce to try(no success previous years) and various other veggies. I have other images available if wanted.


Thank you for contacting Toronto Master Gardeners about the process of hardening off your seedlings.

Perhaps the daytime temperatures were rather low which along with the gusting wind was challenging for plants accustomed to the warmth and calm atmosphere of the grow light. It is recommended to be 10 degrees Celsius outdoors to begin hardening off.

When growing plants under grow lights, or on the windowsill, it is advisable to gently brush your hand over the plant a couple of times a day to strengthen the plant’s stem and gradually get them accustomed to the jostling they will experience in the real world.

This article from the University of Maryland will provide useful information. https://extension.umd.edu/hgic/hardening-vegetable-seedlings

I would suggest that rather than follow the direction on the potting mix package, that you use your gut feeling about appropriate moisture in the potting mix and the specific time and date of hardening off. It is important that a plant’s roots have both water and oxygen available to them. Perhaps it has yet been too cool for the hardening process. This is truly an unusual Spring in Southern Ontario.

I suggest that you water your pots by having them take up water from the bottom, rainwater is best if you can harness some. But also be sure that they are not waterlogged, because that would eliminate any oxygen in the mix. Leave your pots inside until the days are a bit warmer (probably this weekend),

We wish you a wonderful harvest in the summer.