Avoiding sun burn on leaves - moving hibs back outside for spring

[Paul]

Hello everyone,

I'm sure we are all ready for spring to arrive in full force. I have had all of my hibiscus indoors under grow lights since October. With the warmer weather just around the corner, I am looking forward to moving them back outside. I know when I have ordered new plants in the past, the instructions said to slowly get them acclimated to the sun over the course of several days in order to avoid sun burned leaves. I have also read the section on this website about sunburn.

My questions are:
     - How long does it usually take hibiscus to adjust to direct sunlight in order to avoid sunburn, and will it take longer for my plants which have been indoors for several months, as opposed to a plant that has been grown in a greenhouse and then shipped in a box devoid of light for only a few days?
     -Is there an easy method to doing this with several plants? For example, moving them all outside when it is going to be cloudy for several days? Or can I use a tarp to block the direct sunlight after exposing the plants for a few hours each day? Or am I just going to have a daily hibiscus parade from indoors to out, and back again?

Thanks for any input!

[Ernest]

Hi Paul,

When I get new plants that have been in a greenhouse I first place them in a relatively shady spot for a few days so that they get some indirect bright light and then bring them in at night. Every few days I move them out to an area where they get some direct sun--at first just a few hours of morning sun then a little more every few days. I also start leaving them out later at night. Following this routine over about two weeks the plants seem to adapt well to full sun and overnights outdoors. Some plants may start to show some leaf burn sooner than others and I keep these out of direct light a little longer when I see this. I haven't lost any plants to sunburn--they seem to recover easily as long as it doesn't affect the whole plant. I use a wheeled cart with plastic trays on top to move the plants in and out of the house. I can move 12-15 plants at a time this way. This regimen has worked well for me here in southern California. You might need to modify the timing to suit your climate. Since my plants will remain outdoors year round I have to be sure they can take full sun. I use the same method for moving my seedlings from under the grow lights to the outdoors.


Erny

[Paul]

Thanks Erny!

[Charlie]

Good questions, Paul. Ernie's approach seems pretty typical although some other people may have some ideas, too. One thing to watch for is that the pots do not dry out when moving them into the sun - that makes things a lot worse. And, if you do burn some leaves, it's usually not a big deal since new leaves will grow in soon enough to replace old, damaged leaves.

Charlie

[davidwood]

Paul I think you have 2 separate things to do and think about, first getting the cv acclimatized to the sun and then second to avoid sunburn, they are 2 different problems to deal with, there advise ‘slowly get them acclimatised to the sun over the course of several days in order to avoid sun burned leaves’ is a little wrong as it wont work, its good advice as far as getting the plant acclimatized to the sun which you will need to do, by getting acclimatised I mean the plants leaves not going all droopy and the plant looking stressed.
By burning I mean them brown burnt patches and crisp leaves.

What I do is place the cv in the sun and then keep an eye on it, at the first sign of stress bring it in, once its recovered put it back out, it should recover in under 1 hour [if it doesn’t you will need to check if it has enough water] but don’t make the mistake of giving it water to recover quicker as that can become a big problem, if it has enough water let it recover in its own time. Using this method I have acclimatized plants to very strong sun in a few days.

Sunburned leaves are a different matter and I have to say even in my garden which has to be one of the hottest in the world its not a problem I come across often,  the only solution that’s ever worked when I have is to move it  somewhere with less sun. Some CV’s leaves are less prone to burning than others and these CV’s are tougher than you think, as long as they are well cared for [Supernova good fert and water] they can take a lot.


Your idea of moving them outside when you know its going to be cloudy for a few days makes it easier for them and a good idea, you will still need to keep an eye on them but they will stay out much longer before they get stressed.

[Paul]

Thanks Charlie and David! I really appreciate the advice.