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How Much Heat Can Citrus Stand?

Posted by kayakita z8TXAustin (My Page) on
Wed, Jun 27, 12 at 0:15

Have had two orange citrus in containers for over five years. Last fall, decided to plant them in the ground when we moved to a new property in Central Texas.Although soil is clay based, I planted them in a raised bed with plenty of mulch. Trees (about 4ft. tall) survived a two week freeze nicely (well wrapped). Spring brought abundant blooms and three small oranges. Now it's summer with 105 degrees every day. My poor orange trees look pitiful. Although I water them deeply once a day in this dreadful heat, the top half leaves are all curled up with some that appear to be drying out.Have checked carefully for any sign of bugs...Nada. Trees are in full sun from noon till dark. Although partially shaded by live oaks in the early AM, they receive full brunt of the blazing western sun for the rest of the day.Is it the extreme heat that is causing the curling of leaves? What can I do to protect my trees? Would a shade cloth help to save them till weather cools?


Follow-Up Postings:

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RE: How Much Heat Can Citrus Stand?

Sounds like heat to me. Hopefully as they get older and used to the new planting site (I know my trees take a year to show signs of solid growing after planting in ground) they might not react as bad and youll probably get really sweet oranges. Im sure the pros will know. I do know 105 deg is HOT. I would think 75 to 90 is ideal but I have heard of trees surviving hotter.

What kind of orange trees?


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RE: How Much Heat Can Citrus Stand?

Citrus are full sun tropical crops; the heat is not the problem; and it seems you are doing the right thing with water. Curling indicates the need for water; but in your heat you would expect the trees to do that in the hottest times. If your trees look good in the morning, keep doing what you are doing; as the trees get larger and have more reserves in the trunk and branches, they will withstand the heat better.


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RE: How Much Heat Can Citrus Stand?

Isnt that what I just said John...lol?

And yes Citrus are full sun topical, but not full 105 deg every day. You keep a citrus in 105 heat everyday the leaves will start to curl regardless of how much water you give them.

Did you just say heat is not the problem but then go on to say that "in your heat you would expect the trees to do that". Ist that not a contradiction? Not trying to be a jerk, just trying to interpenetrate what your trying to say.


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RE: How Much Heat Can Citrus Stand?

it wouldn't hurt to setup some shade cloth for this summer since you just planted them in the fall. they should be fine next year once they're established.

last spring i had to transplant my two navels, and during our scorching summer last year, they weren't looking too good. so i got some pvc pipes and 50% shade cloth and made a cover for them. this year they're doing pretty good.


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RE: How Much Heat Can Citrus Stand?

Do you have insect screen?

I would push 4 poles into the ground around your tree and lay some insect screen over it. It's cheap and easy. If you double fold it, ever more shade.
What I like about it too that it tends to stay put even on windy days.

Good luck:-)

Mike


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RE: How Much Heat Can Citrus Stand?

kayakita:

Citrus grows in areas of CA and AZ where it can get as got as 124F and regularly hits 110-115F. So 105F or anything else you'll see in Austin isn't too hot. Your problem right now is inadequate rooting. The suggestions about shade this year are spot on. After it's well rooted, hopefully next year, shade won't be needed or beneficial.


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RE: How Much Heat Can Citrus Stand?

I agree that heat is not likely the REAL problem here. For whatever reason(s) the root system is unable to provide adequate water. It might be that the soil system isn't supporting a vigorously growing root system or the the root system has been limited by a planting issue or whatever.

Shade will absolutely help until until the root/soil system issue is resolved, the plant will continue to struggle. Do other things grow well in your clay soil? Some clays are great for plant growth, others.....not so much.


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RE: How Much Heat Can Citrus Stand?

Kaya, I would say the blazing heat, both radiant heat (which is frying your young tree and new leaves) as well as an immature root structure struggling in the heat and not enough water. Screening is going to save your trees, as well as adequate water. And, although mature citrus can tolerate significant heat, young citrus will fry. And, navel oranges cannot tolerate high heat. Once of the few citrus that really doesn't like it blazing hot. So, keep them shaded this summer, mulching is great, be sure to deep water them to get the bedding nice and moist.

Patty S.


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RE: How Much Heat Can Citrus Stand?

Blazaglory, rhizo, Johnmerr, fruitnut, meyermike, houston texas123, and hoosier quilt:
Thank you, thank you for giving me a ray of hope. Everything you have mentioned makes good sense and I plan to try everything.Not sure what kind of oranges I have...bought them unmarked from the local supermarket...Not wise, but they were so pretty and fragrant, I couldn't resist. Most damage seems to be around upper part of trees (Should I remove dried up leaves?) The lower leaves look okay. Trees appear to be a bit fresher early mornings. Have temporarily set up a wire fence cage covered with shade cloth. Will make something permanent when I can get the materials. How much daily water is enough and not too much? Have been giving them about 5 gallons/day. Have a 4 inch layer of mulch around outer paremeter. I'm afraid it's gonna be a long, hot summer.


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RE: How Much Heat Can Citrus Stand?

I would leave the dried up leaves for now. You are most certainly describing sun scorch to me. Without seeing photos, though, we're all still guessing. Those dried out leaves are providing the lower canopy with a bit of shade. Also, I would consider painting the trunk with 1/2 strength flat latex house paint as well, to protect the tender bark from sunburn as well. As far as how much water, I would check about 12" to 18" down, to make sure your soil is moist but not soaked. If it is not very moist, you need to water. And, be sure you've got at least 3 to 4 inches of mulch down to help preserve your soil moisture. And, be sure you're fertilizing every 2 to 3 months, too. Your little tree needs to build its canopy to help protect itself, so be sure you give it the nutrients to do that. And yes, it is going to be a long hot summer for those inland. A repeat of last summer, I'm afraid. I feel for everyone in the midwest.

Patty S.


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RE: How Much Heat Can Citrus Stand?

You should be more worried about cold and soil pH in Austin. Without protection your trees will freeze eventually. Ever notice any large citrus around town? I didn't think so. They also won't flourish in the limestone soil in the Austin area.

Here is a link that might be useful: mrtexas


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RE: How Much Heat Can Citrus Stand?

Mrtexas is right about Austin; my Brother lives there, and with all the advice I can give him, his citrus barely survive. There's lots of reasons Austin is not a citrus growing area; but with care, chelated minerals, some soil amendments to improve drainage, and covers with heat source at the coldest times, you will stand a good chance of survival... and even a small harvest.


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RE: How Much Heat Can Citrus Stand?

All that sounds like great advice for in ground trees. What about container grown plants. We have the same 105 degree heat. To help conserve water and some sun scorch, I moved the under the carport yesterday. Since they are potted I will try and move them to the sun before it gets too hot. Is this the correct approach or should I let them stay in full sun. They are satsuma Meyer and tangelo. All potted for about a year.


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RE: How Much Heat Can Citrus Stand?

arkberry:

With potted trees you need to be concerned about the pots overheating, especially black pots in direct sun. Things I've done to keep the roots cooler are bury the pot and cover it with aluminum foil. Burying also keeps them from blowing over.

Citrus needs full sun but they will grow permanently under 40-50% shade cloth. Moving them under a carport is not a long term solution.


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RE: How Much Heat Can Citrus Stand?

Great idea Steve. The one about foil. I think I'll try that on extra hot days.

Thanks


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RE: How Much Heat Can Citrus Stand?

Mike:

Al foil and a little clear wrapping tape makes a quick fix. Mine have stayed on 6 months in blazing sun so far.


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RE: How Much Heat Can Citrus Stand?

Fruitnut! Thanks a lot. You are right. What a difference on my potted black pots sitting on my hot roof! You are a God send. My figs seem to like this method.

Mike


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RE: How Much Heat Can Citrus Stand?

Fruitnut! Thanks a lot. You are right. What a difference on my potted black pots sitting on my hot roof! You are a God send. My figs seem to like this method.

Mike


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RE: How Much Heat Can Citrus Stand?

I still fight with container citrus trees (and in-ground young trees) in our hot 100+ weather. The in-ground trees do certainly get sunburned badly (not just the young leaves that haven't hardened off from Spring) and the recently planted ones in ONLY the West direct sunlight will sit for an entire year+ before showing growth (these are all properly planted, in raised beds). Ones in partial shade or morning only light do much better and typically show growth in the first spring.

The containers are by far the worst. I've been forced to pot-in-pot on every single one: there is no container mix (gritty, 511, or bagged soil) that can adequately protect roots in direct summer sunlight. The soil temps are easily 100+ around the edges. Yes, black containers are the worst. Supposedly painting black plastic white will drop surface temps 15 degrees.

Besides pot-in-pot (best with 1" of largest bark chunks separating each container), I do have success with wrapping the containers with the foil backed bubble wrap (radiant barrier); alternatively, just burying the container can work extremely well (but careful as roots will leave the container or nearby roots invade). Overall, I think burying has worked best (easiest?) if you don't have root worries.

However, I do also have to put shade cloth over them. The cloth went up for me mid-June (early heat waves here in central CA).

The shade cloth exception: mature trees. If there is a GIANT canopy (very well established tree), this is less important as the outer leaves do protect the interior leaves and bark enough from burning up. That's why you can't compare entire groves of mature citrus trees in hot weather to container or young in-ground. You can't say "citrus are high heat tolerant trees, there are groves of them in 110F weather, heat isn't an issue". It very much is an issue until the tree is very mature and established.

IIRC, all other conditions in place (nutrients, humidity, leaf temps) root temps are ideal growing at 90F but quickly shut down and burn up just over 100F+. Leaf temps shut down photosynthesis somewhere above 115F or so -- which means the majority of photosynthesis occurs is the morning sunlight. It's not ideal to only exposed them in afternoon, but /shrug I have some that are only afternoon exposed due to limited space.


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