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Gardening In The Summer Broiler

cactus1.jpg

Photo by Florence Rogers/Nevada Public Radio

Barrel Cactus

The summer heat is upon us. And this summer, Nevada has seen record high temperatures. How is your garden faring through the brutal summer heat?

Nevada Public Radio’s own Angela O’Callaghan and Norm Schilling, co-hosts of “Desert Bloom,” a regular feature on KNPR, bring their wit and wisdom to State of Nevada to answer all questions related to gardening in Nevada.

Discussion Highlights:

Penny from Ridgecrest, Calif., had two questions: How should she get rid of grasshoppers and why are the tips of the leaves of plants in her garden turning brown?

Angela: Usually, when you see those brown tips what happened was when that leaf was first starting to develop there was a little water shortage. Not enough that the plant was going to die, but it didn’t give the developing leaves quite enough water to develop good cells. As the plant got older, it was able to access better watering and it's able to continue to grow.

Norm: The other thing it could be is salt damage. Salt can build up in our soils. The plants take it up and when the water transpires out the leaf it’s at the very tip of the leaf and it will cause a little die back of tissue. So leaching works. Once or twice a year give your garden a really good, deep soak. And a good time to do that is actually right before a rain. Then the rain comes in and flushes out any other salts that are in our water.  

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And Grasshoppers?

Angela: Have you considered getting a lizard?

Norm: Yeah. Just do everything you can to have predators in your garden. 

Kenny from Cross Timbers he planted several spruce, fir and pine trees this spring but many of them have died.

Norm: The problem with planting in the spring is the plant has a limited time to establish its root system. Generally speaking, in hotter climates, you’re better off planting in the fall, September, October, November. That gives the plants a chance to put its roots out into the surrounding soil.

Also, make sure that your well is large enough, the reservoir you build around the tree that you fill up that it’s going to get water around in the surrounding soil as well. 

Sarah from Ridgecrest, Calif., say the young plants in her garden are suffering and they’re not putting out much growth.

Norm:  This has been a rough summer. Right off the bat, we hit 115 in early June. I don’t think that’s ever happened before and it’s been unrelenting since then. Plants are struggling more this year and we’re only mid-July. The other night it was 10 or 11 o’clock at night and the temperature was 102 or something. These nighttime temperatures are so high that the plants are not getting a break that I think they really want.

What you can do is try to limit the heat load on your plants. Things to help that would be 1) organic mulch. It reflects less heat than rock and absorbs less heat. 2) You can put a shade cloth over a plant to help it through the summer – especially its first summer. 

Jane from Las Vegas has a newly mandarin orange tree that is on a drip system and she soaks it once a week; however, it seems that the fruit has stopped growing:

Mandarin orange tree/Wikimedia Commons

Norm: The first summer here is always the toughest one. You’ve just got to get it through this first summer. You should be watering it every day. Make sure that you’re not only water the original root ball but you getting water out beyond it. There should be an emitter on the root ball that it came in but there should also be additional emitters out around it. Misting a plant off in the afternoon gives it a little break. You don’t have to do it every day, but if you’re out there and the house is handy just make sure you don’t spray hot water on it.

Angela: Fruits is a really intensive thing for a plant because all of its resources are going to get directed to the fruit and if it doesn’t have any resources because the temperatures are ridiculous. It’s going to be a challenge.

Fruit trees take up a lot of water so are they a good idea in the Southwest where water is so scarce?

Angela: Our fruit, even though fruit trees do take some extra water, I believe that the fruit that we grow here in our home yards is about the best testing fruit I’ve ever had – with the exception of apples, apple snob from New York ya know.  While they seem to be water expensive, they’re not so terribly water expensive.  

Is it better because you’ve grown it yourself?

Angela: No! No! It’s our soils. Our terribly problematic soils.  

Norm: The answer is ‘yes’ and ‘no.’ We do have limited water resources and we need to be really thoughtful about it. I’m big a fan of desert landscapes, but if you want to grow a rose through in a dwarf peach tree next to it… so you can choose a portion of your yard.

Peach tree/wikimedia commons

Brent from Las Vegas has ash trees that are starting to lose leaves and branches:

Norm: We’ve been planting ash trees a lot in this valley since the 70s and especially the 80s the ashes came in vogue. What I found is that a lot of ash trees live in lawns – 15, 20, 25 years  – but they ultimately don’t like here.

And they tend to succumb to a disease called sooty canker in which individual branches die off. If you look really closely, you’ve got to search around for it. If you do have sooty canker the bark which is quite thin on ash trees on young wood flakes off and underneath it, you’ll see a blackened area… if you were to touch that it comes off on your finger like you’re touching the inside of a fireplace. It is a terminal, incurable disease.

You can prune the dead out carefully. Dispose of it carefully because it is a fungal disease and can easily spread. But ultimately, I don’t think ash trees are particularly well suited for life in Southern Nevada. 

University of California Cooperative Extention/Sutter-Yuba Counties/ Photo by Janine Hasey

It seems like the African sumac in my backyard is dying:

Norm: African sumacs are semi-summer deciduous. They deal with heat and drought by dropping leaves. Mine has very few leaves but it was last watered in June of last year and it’s okay. These are desert trees. 

We tend to overwater our desert trees – period. What happens is desert trees are water junkies. They think that they’re living in nirvana. In their history, water is their most limiting resource and when its available they use it.

Fast growing trees are weak wooded trees. Live fast, die young applies to trees just like it does to people.

African sumacs are susceptible to a disease called fusarium wilt. It can be transmitted through dirty pruning equipment. Clean your equipment. Sterilize it. Especially if you have somebody come prune your trees, the first thing they do sterilize their equipment before they start pruning.

Finally, if you’re watering these desert trees – these African sumacs – every day I think it creates a condition in the soil for organisms that that African sumac is not normally susceptible in its normal, dry climate, including possibly fusarium wilt. Don’t water your desert trees so much. 

Donna from Las Vegas is concerned because of her plants are stressed because of the heat. I hear you’re not supposed to fertilize plants when they’re under stress. So, should I fertilize at this time?

Angela: No!

Norm: No! Spring and fall only. You don’t want to do it when it’s real hot. You don’t want to do it when it’s cold. 

Skeeter from Overton wanted to know if there is a life span for house plants:

Norm: I don't consider house plants my area of expertise, but here is what I've discovered: More than anything else they die from over watering. Secondly, I don't think I've ever had one die of old age. Maybe that's because I've killed them off before they got there, but most of them seem to be very long lived species.

Angela: The other thing about house plants is you water them and then they dry and you over water and they're sitting in water. You don't want a bunch of water sitting in that saucer for more than a couple of hours, except for maybe African violets.

Jeremy from Las Vegas has a garden filled with a variety of squash, tomato and pepper and they’re all doing well. He wanted to know if he should cut them back?

Angela: If it ain’t broke, don’t fix it. I’ve already had to cut down my tomatoes and hope they come back in September. But I was getting a lot of sunscald. If you’re not getting sunscald, if the tomatoes are still producing and they look good, they're ripening fine - just keep going. 

Sunscald/Wikimedia Commons

My tomato plants are producing but they’re not turning red:

Angela: That’s the heat. A lot of times if the heat is too much the compounds, the proteins that produce the red coloring. It’s not that the red coloring is dying. The compounds that produce it are not able to tolerate the heat. With tomatoes over 90 degrees, they’re pretty much unable to turn red.

However, that’s when you take them off the plant take them inside and put them on the window sill and say – okay now ripen.

John from Pahrump had an apricot tree that gave them a lot of apricots over the past 10 years, but it has died back.

Norm: What can happen with these trees is they can outgrow their wetting pattern. The more leaves you have the water you need to support those leaves. One of the most common things, when trees have done well then go into decline, is because they’ve outgrown their wetting pattern.

You want to keep the soils fairly moist, keep a wide wetting pattern, use organic mulch and hope for the best. Ultimately, most members of the prunus genus don’t have a lifespan much longer than 20 years anyway.   

Dick from Las Vegas has problems with insects on his mimosa tree:

Norm: Arborists call mimosas bore bait. You plant a mimosa you’re asking for bores. They’ll come usually five or 10 years after planting. Individual limbs start dying and they’re bores. I won’t treat for bores in flowering trees because the chemical we used to use is a neonicotinoid. It gets taken in by the plant, gets translocated into the flowers and nicotinoids are suspected in bee decline I don’t want to be part of that.

I like mimosas. They’re beautiful trees but I don’t want to grow them just because they’re hard to keep alive here. 

Joy from Las Vegas has a North American saguaro amongst a lot of cacti and it gets water every three weeks on a slow deep soak. Normally, they notice growth on it in June, but this year they’ve not noticed anything:

Norm: They’re pretty drought tolerant. You know what, it’s because this summer is just awful. I don’t know why else.

Angela: You know because the temperatures spiked. There wasn’t anything remotely close to a gradual rise. Most of the plants are going into some kind of shock. 

David wants to know the best time to cut back oleanders:

Norm: Do it in the winter.

Angela: You don't want to do it when the sap is flowing. 

 

RESOURCES: 

University of Nevada Cooperative Extension Clark County

University of Nevada Cooperative Extension Horticulture Program

Master Gardeners

growyourownnevada.com

Mountain States Wholesale Nursery

High Country Gardens

International Society of Arboriculture

From Nevada Public Radio: Desert Bloom

Guests

Angela O'Callaghan, associate professor, Nevada Cooperative Extension; Norm Schilling, horticulturist