With Fall Coming, Here's How Not To Kill Your Plants

Fall is coming. But is that also the end of your summer gardening?

In a little over two months, Nevadans might legalize recreational use of marijuana. If that happens, some people will be able to grow it privately. But what's the best way to grow it?

Desert horticulture experts Norm Schilling and Angela O'Callaghan join the program with tips, clues and solutions to fall planting questions and problems.


On the dangers of trimming palms:

Norm: What's really dangerous are these older palms that haven't been pruned in years. They develop what we call a skirt of dead fronds and what can happen is those fronds can come loose. 

When someone is working on them, they're tugging on them and that whole skirt can come loose and if it comes down from the top, it knocks the next one down and the next one down and the whole thing comes down on top of them. And it pins them. It either pushes them back and crushes their chest, keeps them from breathing or pins them against the palm and they suffocate. 

Caller Alysse wanted to know how to get aphids off her herbs:


Angela: Insecticides are pretty much useless because they multiple in a heartbeat. If you can, get ladybugs or praying mantises or lacewings. I know that some of the local nurseries have ladybugs. They'll chow down on these things. They won't stick around but they do love to eat aphids.

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Norm: Lacewings are those little light green flying insects near your porch light. It's the larva that eats them. You can purchase them and have them shipped to you. They're like little miniature alligators and they eat 100 times their body weight and walk a mile.

The thing about aphids is you really shouldn't use pesticides because aphids are part of the food chain. In fact, they're a major chunk of the food chain. 

The predators are smart. They realize there is a food source so they lay their eggs near a plant that attracts aphids. If you resist the use of pesticides, you encourage predators to move into your yard. Then ecological balance happens. 


Recommended company to order insects: Rincon-vitova

Caller David wanted to know how to help his orange tree:

Norm: All fruit trees should have organic mulch, which is wood chips. Don't pile it up against the trunk because that can trap moisture against the trunk, basically cover the ground in wood chips and over time they slowly break down and work into the soil. Trees can out grow their water sources. Don't move emitters from the base of the tree, but add emitters to get the wetting pattern out.  

On changing Southern Nevada's alkaline soil to be more acidic:

Angela: You can try soil sulfur. Soil sulfur is 90 percent sulfur and 10 percent clay. It is very slow and you can use that a long with organic mulch. You can also try putting a layer of compost under the wood chip. 

Norm: We used to buy soil sulfur as a powder. Now, it comes as pellets. When you put it in soil and you dig the soil back up three or four years later you still encounter the pellets. It is only in their dispersed state that they really work. What I do is put in a bucket and add some water and make a slurry the night before and then add that to the soil.

Caller Cynthia's succulents are rotten in the center and shriveling up:

Norm: If they're rotting at the base or at the center, it's usually because they're staying too wet. If they're shriveling up at the ends, they're getting fried. 

Make sure you don't plant succulents too deep. They're in a little bowl. Plant them a little bit high. Plant them high and proud. If you're planting little three or four inch succulents you might only raise it up a half inch. That helps keep air in that root ball. Everybody knows plants need water but we don't think that our plants need air. They need air as much as they need water.  

Angela: It could be that those plants are getting so much water and that soil is so rich and holding onto water as well. Plants will hold onto as much water as they can, especially if they're desert adapted.

Caller Karen has a Texas olive tree in her yard and the leaves are turning yellow and falling off.

Texas olive tree/wikicommons

Norm: Texas olive is a very, very drought tolerant tree and if you are watering it four times a week, you are probably over watering it. You could probably do it once a week or less. I think that might be part of the reason that it is dropping some leaves.

Water it once a week. Give it a deep soak in the summer and twice a month in the spring and the fall. And it should be fine.

Caller Chris's sod, which was put in in March, is not thriving:

Norm: There is probably one of two things. One is sprinkler coverage. A sprinkler isn't watering the area immediately in front of it. It should be head to head coverage. They have to reach each other. Sometimes if a system is not well designed you have these gaps in coverage. It can cause areas to decline and die and not get enough water.

One of the common mistakes people make is time of watering. When you first put the sod down, you have to water three times a day: morning, late morning and early to mid-afternoon to get it to start. But within a week or two go back to twice a day, then a few weeks later back to once a day. And after at that point, only water in the morning. If you water at night the water stays down at the base of the leave blades. It is kind of like our toes. You can get your toes wet no problem, as long as they're allowed to get dry. But if you leave them moist long enough, you get a fungus. If you leave a plant moist long enough it gets fungus. Don't water in the evening. Don't water at night. 

On hawk moth and sphinx moth caterpillars:

Angela: These are insects that will defoliate a tomato plant overnight. You know the book the "Very Hungry Caterpillar?" This is an extraordinary hungry caterpillar.

They are horned worms. They have horns on their tail. There are a number of different horned worms but the ones we worry about are these guys. They can be as long and thick as your index finger.

There is not a lot you can to but use diatomaceous earth and BT, Bacillus thuringiensis. What this does is it produces a toxin that kills larvae 

Caller Scott wanted to know what plants attract hummingbirds:

Angela: They go for tubular flowers. Red is their favorite. They go for things like red yucca, which produces a stalk full of red, deep flowers. Long bloom season. 

Red yucca/wikicommons

They kind of like cape honeysuckle, which kind of produces a long flower.

Cape honeysuckle/wikicommons

They also like aloe vera, which also produces a big stalk with flowers.

Norm: There is a flower called autumn sage and it likes a little bit of shade and a little bit of extra moisture. But it blooms almost all year round and it's a hummingbird magnet. Another one is coral fountain - lots of little tubular flowers - real long bloom season, takes a lot of sun, gorgeous plant, hummingbird magnet sucks them right in. And even lantana does a pretty good job.

Autumn sage/wikicommons

Coral Fountain/wikicommons


Caller Albert wants to know about his tangelo tree which looks half dead: 

Norm: A lot of times when you see die back in a tree and half of it dies and the other half seems fine, often times it corresponds to something that happened in the soil on one side of the plant. Not necessarily the same side because that vascular tissue can spiral up the trunk. So, it's possible that something got spilled there or put there.

But if half of it is dead and half is alive, trees, plants want to grow and they are very space and light aware and so slowly over time, as long as that plant remains healthy, those existing branches can start filling in that area that died back. You were right to prune out the dead and then let the live tissue fill back in. 


University of Nevada Cooperative Extension

Master Gardeners

Mountain States Wholesale Nursery

High Country Gardens

International Society of Arboriculture

From Nevada Public Radio: Desert Bloom


Norm Schilling, Schililng Horticulture

Angela O'Callaghan, associate professor in social horticulture, Nevada Cooperative Extension



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