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hendi_alex
Super Green Thumb
Posts: 3604
Joined: Sun Jul 06, 2008 7:58 am
Location: Central Sand Hills South Carolina

Get those seedlings in the sun and air as soon as possible.

Get those seedlings outside into the fresh sun and air as soon as possible. On sunny days from 50-60 degrees, mine go into one of two small twin wall cold frames. When the temperatures hit into the sixties or higher, the plants sit on a south facing front porch that acts like a solar collector and gives an extra few degrees of warmth. Seedlings grown in the sun and wind, from my experience, tend to be much tougher plants and require no special treatment before going into the final outside planting area.

Here is a shot of my first two batches of plants in one of two portable cold frames. There are four larger plants in individual pots, and then there are two small pots containing multiple plants. Those will be re-potted into individual pots tomorrow.

Note: If seedlings grow for more than a few days in artificial light or low intensity light conditions, they will need to be gradually [hardened] moved into the direct sun and wind. When that is necessary, I start mine in semi shade with some kind of wind block, gradually moving them toward the direct sunlight and gradually removing the wind screen.

[img]https://farm4.static.flickr.com/3273/3280818627_47661bd660.jpg[/img]

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JustPeachy
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Posts: 29
Joined: Thu Jan 29, 2009 12:16 am
Location: Eastern NC

This is super helpful. You must've read my mind b/c I was about to post a question about this topic. How long does it usually take for tomato plants to harden off? Thanks for the informative post!!!

~Emily

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hendi_alex
Super Green Thumb
Posts: 3604
Joined: Sun Jul 06, 2008 7:58 am
Location: Central Sand Hills South Carolina

I've never really paid that much attention. They are placed in semi shade for several days and are also given some kind of wind break if it is particularly windy. After about four days the plants get moved a few feet toward the bright light, and that continues every few days until the plants are in full sun. I would guess about 10-14 days to be on the safe side. I almost never buy transplants that are growing under shade cloth or those that are on lower racks and in mostly full shade. I want my transplants ready to go, so buy those that have been continuously in full sun. Occasionally there is no choice, and so those plants must be hardened. Otherwise the leaves will scald and turn white and more than a slight breeze will cause the plant to dehydrate and wilt to the ground. An alternate way of hardening is to place the plants where they get about two hours of morning sun. Each day or two, move the plant to where the shade hits it just a little bit later. Pretty soon they are in several hours of sun per day, and will do just fine.



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