Скачать или смотреть Hardening off mature tomato plants

A look at how I harden off my 6 week old tomato plants that have been growing under grow lights. Do NOT try this with much younger plants as it will likely kill them or at best stunt their growth! 4 week old at minimum is what I would recommend.

The point of hardening plants is to allow them to acclimate to both the wind environment and the intense sun outside. No matter how bright your grow lights may be, they cannot compare to the brightness of the sun and always the UV rays it produces.

This simple method is to leave them in a shaded area on the first day for up to 6 hours. If any start to wilt then bring them inside and water them, but most should not wilt. On the second day leave them out for almost the whole day but only with no more than an hour or so of direct sunlight. If none of them are wilting at this point after the full day then you should be able to leave them outside overnight as low as the overnight temps are above the low 40's F or 5C. You then should leave them an extra day in an area that gets direct sun but not all day.

This is just how I do this, there are many other ways to do this as well. Whichever method you choose, best of luck to you!