Italian cypress grows too tall to be used in residential landscapes

A: I receive a lot of complaints about Italian cypress from people. These complaints range from the branches flopping to browning from borers and problems with spider mites.

The flopping branches are an easier solution. Water and fertilize them less often. They are large Mediterranean plants so they like dry, hot summers and cool moist winters. In my opinion, they do not need to be washed down weekly, just after a major wind event and blowing dust.

Italian cypresses are large trees reaching at least 50 feet tall and should not be used in most residential landscapes because of their height. The biggest mistake made, I believe, is watering too often. Watering frequently promotes rapid growth (floppiness) and can cause tree death from root suffocation. Water these trees deep but infrequently.

How does that translate to your landscape? Give them a lot of water when you do water and water no more than once a week apart, two weeks if they can handle it.

Golden dwarf arborvitae gets spider mites. You are not going to get around that. But as you mentioned, they are much easier to spray and hose down with water periodically for dust control.

Irrigate them more frequently than Italian cypress. The dwarf forms are smaller trees so their roots don’t grow as deep. But if you water them frequently or the soil has poor drainage, they will have similar problems to Italian cypresses. They won’t be “tight” anymore; they will turn brown and may even die.

It’s smart that you’re looking for a dwarf selection of arborvitae because standard sizes can get big and not suitable for small landscapes.

Q: I bought the Bayer insecticide for borers a few months ago. I but never applied it because I wanted to eat the peaches. Peaches are looking good now but the borer damage is still there. I am hoping the borers have moved on because I have not seen any new damage.

A: You probably will not see any new damage to the tree until temperatures cool off a bit. Make sure to read the label directions for the product you bought. Some of the Bayer insecticides for controlling borers should not be applied to fruit-bearing trees.

You must wait 12 months after applying some of these products before you can eat fruit from it again. So, in your case, if this product is not labeled for fruit trees then you will not have fruit to eat the year following an application.

Borers frequently come back and damage the same trees over and over again. Borers survive from egg to adult for one growing season before their cycle repeats. They may exit the tree as adults around May or June and then reinfest the tree with more eggs a few weeks later which intensifies the damage. This cycle repeats itself until the tree dies because they often come back and reinfest injured trees.

This Bayer insecticide — and insecticides like it — are systemic, which means this poison is taken inside the plant where it’s ready to kill new borers the next time it’s under attack. Because it is systemic, it should be applied after the tree flowers to avoid harming honeybees.

Q: Why does my healthy-looking hibiscus drop its flower buds before they open?

A: Dropping of flower buds is usually because the soil becomes too dry before it’s watered again. There could be other reasons, but this is the most common.

Frequently this happens during the spring and early summer months to hibiscus, camellia and gardenia when their need for water changes rapidly from day to day or from one week to the next. It’s common with plants grown in containers because it is more difficult to monitor rapidly changing soil moisture in containers during this time of year.

Try applying a 2-inch layer of woodchips to the top of the soil. If this plant is in a container, shade the outside of the container so it doesn’t get hot. Soil applications of woodchips help keep the soil surface from drying out rapidly on hot, windy days. Flower drop is not common during the cooler times of the year.

Q: I purchased a tomato plant that grew slowly and curled and twisted back on itself. I removed it and am now looking for a new plant to replace it. What caused this?

A: Hard to say. Sometimes we get plants that are unhealthy. This morning I pulled a pepper plant out that didn’t look like any of its neighbors. It probably had a virus and was twisted and curled like yours.

It is better to remove these plants as early as possible and replace them or leave the space unplanted. If this is a virus problem, it can be transmitted to other plants through insect vectors such as aphids or whiteflies and the problem worsens.

I am wondering if you have enough time left to get a crop of tomatoes before the heat stops production. Ninety-five degrees is the magic temperature when tomatoes stop setting fruit unless we get a cool spell or rely on a fall crop. Pepper and Chinese eggplant produce better during high temperatures, in my experience.

Q: We have two 10-by-10-foot planters made of pavers and I want to plant a Red Push Chinese pistache in them. I am worried about damage to pavers from the roots. Irrigation would be from a drip irrigation system on a timer.

A: A Red Push Chinese pistache tree can get 50 to 60 feet tall with supplemental irrigation. In my opinion, this tree is too tall for most residential properties and for your planters. You need a large landscape, park or city streetscape to accommodate that size.

The size of the planters should not be a problem for about 10 years when planting Chinese pistache if using a coarse-textured soil enough for good drainage and not planting shallow-rooted flowers in the planters. They require frequent, light irrigation, which forces roots toward the surface of the soil.

When planting something else there, select plants that have deep roots similar to the tree and don’t require frequent irrigation. But, eventually, Chinese pistache will outgrow these planters and lift the pavers.

Select a smaller tree for those planters. My guess is you like their fall color and that’s the reason for their selection. Select trees in the same scale as your home and landscape. Remember, larger trees usually use more water. What shape should they be? Arching? Round? Upright? Flowering? Deciduous?

Q: You talk about controlling the height of fruit trees by topping them. When is this done?

A: All height control is done in the winter just before dormant pruning begins. It’s not done by topping, which is a no-no. It’s done through a pruning technique called “drop crotching.”

First, lower the height of the tree by removing the tallest branches at a crotch with a side branch. After lowering the height, then prune for any change in its overall structure and finally focus on pruning to improve production.

Q: My Honey Crisp apple was at least a month later than the others in leafing out and only had one small cluster of blossoms. The tree looks good now with only a blossom or two. Is there any hope it will produce fruit in the coming years?

A: I’m guessing this is a new tree. I have never grown Honey Crisp apple. The tree grows fine. It’s more about how it will produce apples in the future and the quality of the fruit from year to year.

It is normal for apple production of newer varieties to start around their third year. Some precocious apples like Pink Lady and Sundowner start producing fruit by their third year in the ground from a 5-gallon nursery container.

But as they start producing fruit, the yield should increase exponentially. So, two apples this year should mean more than 10 next year. Expect full production by the fifth or sixth year.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.