Author Topic: Semideciduousness and subtropicals - how does it work?  (Read 1568 times)

Solko

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Semideciduousness and subtropicals - how does it work?
« on: April 13, 2016, 04:31:40 AM »
I grow subbtropical plants in a temperate climate and overwinter some inside to protect them from the hardest frosts. The downside is that they need to stay inside in a dark garage, so they don't get the same amount of light they would get outside.

And I have been puzzled by the behaviour of some of them, so I wanted to ask if any of you had any thoughts on this.

Some of them (Jaboticaba, Campomanesia, Backhousia, Pitanga, Pitomba, Grumichama) stay green all through winter (inside and outside) and lose their leaves only when I put them back outside in spring. Of these some appear to be dead, only to come back after a month or two with new leaves. But some actually are dead and some others only come back to life if put in indirect light, when temperatures warm up, while direct sunlight seems to kill them off...

I know that putting them in the garage somehow triggers a natural response in the plants, but how am I supposed to think about these semideciduous subtropicals? Should I as quickly as possible give them light and sun in spring? Even if it is still a bit cold outside? Or should I keep them warm inside in the dark until late spring and let them get used to the outside in indirect light again?

I mean, for normal deciduous plants, to put them in a warm garage may actually disturb their dormancy, make them leaf out too soon, and then kill off the young leaves when I put them outside in early spring. I have the idea that for some plants I may disturb their dormancy by putting them inside and then back outside...

For others I know they need protection from frost and that they change their leaves in spring, but do I need to put these in full sun once they are back out, so that they can heat up and get energy as quickly as possible?

I don't now what kills my plants that do not survive. Too long of a wait in the dark, or too early and bright sunlight back outside?

Any thoughts or experiences would be very welcome.

« Last Edit: April 13, 2016, 08:02:07 AM by Solko »

stuartdaly88

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Re: Semideciduousness and subtropicals - how does it work?
« Reply #1 on: April 13, 2016, 08:14:38 AM »
Im no expert but I think of it like this:

in the middle of summer with my dark tan I can spend a few hours outside shirtless no problem but after winter where Iv always worn at least a tshirt when outside for like 4 months when I first go shirtless outside in spring even 1 hour can burn me badly and I peel.

Lemon trees if its been cold for awhile and they are dormant can take quit abit of cold but blast a late springlemon tree with frost and it will get badly damaged.

I think just like us plants just dont like drastic changes. They need to aclimatise slowly to new conditions. If they were in a dark garage all UV protection would have been thrown aside as they desperatly try for any light possible then one day you shove them outside in that state!.

Maybe get a HID light or two for your garage? even a skylight would be even better. My young plants do really well on window light mid winter but even then still need to be eased back into strong sun!
Patience is bitter, but its fruit is sweet.
-Jean-Jacques Rousseau

Stan

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Re: Semideciduousness and subtropicals - how does it work?
« Reply #2 on: April 14, 2016, 03:23:00 PM »
Also- some if not most tropicals in a temperate climate react to longer days also.  Its not summer like here..and my largest Mango is flushing with one branch flowering. Its like that every year. You cant go by books. You have to try. As of right now- even Santol is sending out new leaves. Imagine that. IT is supposed to need full warm days. April has been 66or 68f?
Nature has built in back up systems to plants we could never guess at until we try them.

LivingParadise

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Re: Semideciduousness and subtropicals - how does it work?
« Reply #3 on: April 14, 2016, 10:57:45 PM »
I would keep them warm, and give them a light at least occasionally - plants generally will respond to even artificial lights that are not grow lights, and can even do so if it's not full-spectrum. Avoid tossing them out before temperatures are consistently warm enough.

It sounds like you're not hardening them off. You can't just toss them out into full sun after being in the dark. If you want them to live, first you need to find a way to get them more light where you keep them in the garage, even if it's only for a few hours once a week. But throw them a bone, they are not made for constant darkness - especially the full sun species. And then you need to gradually introduce them to indirect light, then full sun only an hour or two, and then increase until you can keep them out all day. Hardening off in such drastic conditions might take 2-3 weeks before you can just leave them outside. Otherwise, they're going to have a hard time surviving, and even if they do, growth will be stunted because they're spending all their energy trying to recover from damage rather than being able to grow further, let alone push out fruit.

I would really encourage you to keep a few of the most sensitive varieties in the house, unless of course they are huge. Then you have to monitor for humidity, and may need to spritz them regularly with a water sprayer to help them out (indoor heat is terribly drying), but they will have more consistent light and warmth. If not, consider placing a space heater and a grow light in the garage, even if you only bring it out and run it for a few hours a week, so they can avoid these drastic seasons of ups and downs of darkness and cold and then heat and light, which they are not designed to be able to handle. They're going through too much stress, and likely that causes you to lose some of them, while the others will drop leaves but then put all their energy into recovery.

I don't think this issue sounds like it is related to being deciduous, otherwise what you would see is dropping of leaves all at once as soon as temperatures dip, especially once they have been put in the garage. Losing leaves only when they enter the outdoors again, and doing poorly in direct light, means you're not hardening them off before introducing them to full sunlight. It IS similar to human skin without melanin as a natural protection that way, you have to slowly build them up to be able to handle more light than they've been getting, otherwise they will shed their leaves like people would shed burned skin.

Solko

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Re: Semideciduousness and subtropicals - how does it work?
« Reply #4 on: April 15, 2016, 04:48:17 AM »
Thank you for all your replies!

I believe I am starting to develop some understanding about this. I have still one question left, which is simply: Once a semideciduous tree has gone into 'leaf shedding mode', is it then best to let it leaf out again in an exposed and sunny spot, or in a protected place with diffuse light?

I'm asking this, because I have lost plants while doing both things last year. Some I put in direct sun, once they were bear and they never seemed to recover, others leafed out again first in a protected spot and then defoliated again when I moved them into a sunnier spot later, and that did them in for good.

I only have experience with real deciduous trees like figs, and they love to be put in full sun, once the winter is over, but before they leaf out.

I did underestimate the need for these semideciduous plants to harden off. And so I will pay much more attention to that this year.
My citrus, Ugni's, Strawberry Guava's and Myrtle, which have been under the balcony during winter, love to be moved to the sunny spot in early spring. No leaf burn or discoloration. Just happy green plants and new buds swelling. But these can be considered evergreens. The deciduous figs also love to be put in full sun after winter, so that they leaf out with solid, sturdy leaves.

As for the 'semideciduous ones: After close inspection and reading your remarks, I see that my Pitanga's, Campomanesia's, Jaboticaba's and even my (evergreen) Feijoa's, all of which also spent the winter outside under the balcony, do get sunburn when moved back to the warmer sunny spot.

And that can make the difference of them going into 'defoliation mode' or not.

I guess what is confusing about this is that the different species seem to have different triggers for going into 'defoliation mode'. Some of them, Eugenia Florida, Backhousia and Grumichama loose their leaves in autumn, or midwinter in the garage. And these seem to want to leaf out too soon, in the window still inside, which makes the new leaves really tender and fragile.

To be clear, I do have lights in the garage - it is more of a workspace, and it has one entire glass wall. The temperature in the garage is also higher then ina 'normal garage', since I work there. Light conditions are not oprtimal for plants, but they do get enough light and maybe even a little too much warmth in winter.
At the end of the winter they also get two to three hours of diffuse sunlight in the window, and some of them start to grow very tender growth again... That growth is too tender though, and one of the reasons why I want to move them outside as soon as possible. So that they can leaf out with more sturdy leaves.

I guess the UV factor in hardening off is more important than the temperature factor after winter. I'll pay more attention to that, but for this year that leaves me with the question I stated: Is it better to give a defoliated small tree full sun, so that the leaves that come out are hardened off, or is it better to keep these in a protected spot, let them leaf out and then slowly harden them off?

I guess I may eventually answer this question myself; I have split the defoliated plants in two groups and will let you know the results in a couple of months.

But in the mean time: all thoughts and experiences are very welcome,  :)