Hardening off

[miniedmo]

If you don't harden off your plants at all, what are their chance of surviving?

[Suze]

Hard to say; lots of factors involved.

If it's hot (or fairly cold), sunny, or windy when you set them out, there's a chance they may not make it. At the least, foliage will be damaged, which will set the plants back as they grow new foliage.

On the other hand, if it's moderate in temperature, fairly hazy and relatively calm when the plants are set out (and for several days afterwards), they might squeek by.

Personally, I always harden off. It just doesn't make sense to me to expend the time and effort involved in raising seedlings and then gamble by planting without hardening off.

[pooklette]

I'll give my opinion on the matter by telling you the story of the ONE year I didn't harden off my plants properly.

My first year gardening, I tried to harden off my plants before setting them out but went about it all wrong. If ever there was an example of a newbie 'oops', this would be it.

The seedlings had been pampered to the fullest for weeks in the house before it was warm enough to set them out. I had heard that you have to acclimate them to outdoors conditions so I figured, "I'll just set them out for a few hours each afternoon and then bring them in again." Big mistake.

On a gorgeous, sunny day (probably about 70 degrees out at the time) I set my plants out and left to run some errands. By the time I got back, maybe two hours later, my beautiful plants had all flopped over like they'd fainted and the leaves had gone a deathly pale color. I rushed them back in the house, gave them plenty of water, and put them back on their shelves. Two hours outside nearly killed them.

Most of the leaves died off and the rest of the plant remained that sickly pale color for weeks. I did transplant them into the garden but the plants were stunted and...well, homely would be the best description, I guess.

Everything I set out was like that, even the ones done on partly cloudy days. I ended up having to buy transplants from one of the local big box stores because I wasn't sure my original ones were going to survive.

Perhaps some can set their plants out without hardening off but I am clearly not one of those people. I vowed never again to risk it and made sure I learned to harden off the plants properly. I'd just cry if my hundred-and-some healthy seedlings withered into those pathetic, pale, wilty things I ended up with my first year.

[miniedmo]

Well, the reason I ask is that I am at work all day and really don't have time to harden them off the way I understanding it here. I have a screened deck that I could leave them on but they would have to stay there all day until I get home. Will it hurt them to say, sit them out on a covered deck on a 70ish day and leave them there all day long for the first time?

[Suze]

Originally Posted by miniedmo

Well, the reason I ask is that I am at work all day and really don't have time to harden them off the way I understanding it here.

Ah, okay -- I understand.

Depending on your work hours and assuming a normal M-F work week, I'd start the hardening off process on Thurs.

Thurs - Put them somewhere in all day shade, where they'll be somewhat protected from any harsh winds.

Fri - Push them out a little where they get either bright shade or an all day dappled shade (much more shade than sun).

Sat - One hour full sun, the remainder of the day put in shade or strong dapple. 30 min in the early morning, 15 min increments 2x later on in the day. Letting the plants rest between the increments allows them to take a little more in total during the day. Important: be sure and watch/note where the sun path/pattern is during the weekend, so you'll know where plants can safely be set to continue hardening off during the week.

Sun - 1.5 - 2 hours full sun, remainder in dappled shade. 45 min to 1 hour in early morning, the rest in increments split throughout the day.

Mon - site plants where you know they will only get 2-2.5 hours max sun during the day.

Tues and onward - keep gradually increasing sun increments, keeping in mind the weather forecast for the day. Once you get to day 4, plants may very well be able to take most, if not all of the day under the canopy of a tree (use your judgment on this).

As others have noted, shade cloth can be helpful. A plastic clothes basket can also be helpful in the early stages of hardening off if you really can't watch them. It protects from the top, yet allows some indirect sun to stream in through the holes in the sides. After a couple of days shade exposure, put seedlings under the clothes basket. Weight down on top with a brick/rock so it doesn't blow off.

[Worth1]

I didn’t harden off this year but the plants had little time to get used to the indoor life any way.
From seeding in the house to planting out side, just two weeks.

But I give very little advice here on planting tomatoes as I have a very green thumb and if most of the other folks tried it the plants would die.

My plants are now around or close to 2 feet tall and looking great.
I think I may have found the trick for my situation with the work in Alaska.8)
I know I thought long and hard about it.

From house to shade is the best way then to full sun gradually.
You just have to keep an eye on them.

Best wishes,

Worth

[caascher2]

I work too and have been hardening off some perennials the last few days. I have an area where they get morning sun, and then shade the rest of the day. So far so good. Of course the sun isn't at it's strongest yet so the exposure has been fine. I will do the same for everything else in a few weeks when we can put the veggies out to be hardened off.
Wish you luck!
Carol

[feldon30]

If you work earlier or later in the day, then you can try to ramp up the number of hours in the morning or the afternoon only. If you start hardening off on Sunday, then the flexibility of hours on the weekend will allow you to start pushing them in the morning AND afternoon, with a CRITICAL break in mid-day when the sun is the hottest.

Day 1: Full shade (patio, porch, etc.). No sun at all!!
Day 2: Full shade + 15 minutes afternoon sun.
Day 3: Full shade + 30 minutes afternoon sun.
Day 4: Full shade + 1 hour afternoon sun.
Day 5: Full shade + 2 hours afternoon sun
Day 6: 1 hour morning sun, mid-day shade, 2 hours afternoon sun
Day 7: 2 hours morning sun, mid-day shade, 3 hours afternoon sun
Day 8: Sun except 11am-2pm

This may be too accelerated for some areas. I know it was too fast for my plants here in Houston and I burned a few.

If you have some guaranteed dappled shade in your yard, that is really the best area for hardening off. Also, if you have a couple of days of completely overcast days (don't trust the nozzles at the local TV station, check WUnderground.com's hour-by-hour cloud cover percentages), that's a good day to get them outside all day.

If you just don't have the time to give them some morning and afternoon sun without leaving them out in the blistering mid-day sun, some other tricks you can try are to place a wide board (supported by bricks, blocks, etc.) over the plants so that as the sun moves across the sky, the plants will be completely shaded for several hours in the middle of the day. Another trick is 40% shade cloth.

When in doubt, give them LESS sun rather than more.

I'm sure there's some money to be made in a battery-operated hardening off kit.

[dice]

What about putting them on the north side of
a building, where they don't get any direct sun
at all? Anyone tried that? Maybe in a cardboard
box with sides high enough to buffer wind gusts?

(Watch out for slugs, too. One might want to stake
out a box turtle nearby for that.)

Edit:

They do have to get used to direct sun
eventually, of course, but for the first
couple of days, perhaps the north side
of a building is a safe start.

[miniedmo]

Thank you everyone for the good advice. Should I go only a week or should I harden them off for 2 weeks?

Thanks again to everyone!!!!

[Suze]

Originally Posted by miniedmo

Should I go only a week or should I harden them off for 2 weeks?

If you start hardening on a Thurs, they would probably be fine to plant the Sunday after next. That gives ten days and three weekend days for you to really work with them. The Saturday before planting out, they should be able to be out all day without looking stressed or wilty. Observe, then go from there.

[rxkeith]

what has worked for me for several years is, plants go from house to inside front of garage facing east. they get a little morning sun, some protection from the wind (if not an east wind) after a couple days they get moved closer to the front of the garage until day 7 when they are exposed to the elements. they also hardened off successfully on the back deck which had a lattice work trellis on one side. the plants were placed at the bottom of the lattice which gave them dappled sunlight for most of the day. depending on how many plants you have, you could do something similar with some lawn chairs or laundery basket. just make sure the wind doesn't blow them over. once they get past the first 3 days or so, they can take a bit more sunlight without much harm. a weeks time hardening off is all you need

keith in calumet

[celticman]

I start mine inside and move them to a cool garage under lights within days. Then it into the sun as soon a possible shade one day, a couple hours of sun light and then full sun. Aside form coming in when it going to freeze they are outside day and night (they do spend a lot of night in doors). I would not put 6inch seedling in the full sun that had been pampered inside. In the shade a day or two and work out into the full sun slowling on a day off. Read the plants they'll tell you.
I know for a fact many of my plants are beat up from the 50 mile and hour wind gust we had yesterday. They are however throughly hardend off and will rebound in a day or two and I am not aiming to get them into the ground until the first of may.

[miniedmo]

I will try all the information you folks have given me and will let you know if I mess it up. This is my first year starting from seed and am pretty excited about it and a little worried.