Trees normally grown as shrubs tend to sucker a lot

Q: All my trees send suckers up around their base. I have a drip system and water three times a week for 20 minutes. What am I doing wrong and how can I stop this sucker growth?

A: It is a mixed bag. Sucker removal and how often it’s done depends on the plant, how old it is and how the suckers are removed.

Trees sucker more if they don’t get enough water. I don’t know if your trees are getting enough water or not. Twenty minutes of water three times a week doesn’t tell me how much they’re getting.

Trees that normally grow as shrubs tend to sucker a lot. Others that grow more like trees don’t. When oleander shrubs are grown as multi- or single-trunked trees, the suckers must be removed all of its life. Mediterranean fan palms are in the same boat. But mulberry trees don’t though they can easily sucker under the right conditions.

Some plants produce a lot of suckers when young and rein in this characteristic as they get older. Most suckers, like weed control, stop sending up more if the suckers are removed as soon as they are seen instead of waiting until they get larger. Sucker removal must be done as soon as you see them rather than wait.

How suckers are removed is also important. If you remove suckers when they are young, you can hand pull them or rub them off with your hands or fingers. That’s easy.

It’s more work if you must use hand pruners and forced to remove them by cutting. Not only that but if you leave stubs behind, new growth will arise from those. When you leave stubs, figure that you will get three new shoots for every one that is cut.

There are sprays you can apply that decrease the suckering. They have names like Sucker Punch and Sucker Stopper, but these sprays may just end up being a temporary fix. Anytime you use these chemicals, follow the label directions.

Q: I intend to remove the rock layer around my roses and apply a 3-inch layer of quality compost, dig it in carefully and cover it with western red cedar bark. However, the rock layer is convenient for blowing out all the leaves that fall from other plants around my roses. How do I keep the rose area clean with a blower and use bark mulch?

A: There is a way to make your roses happier and still leave the rock in place. I understand it was convenient because your maintenance people would come and blow away all the debris with a power blower. With cedar bark, power blowers will blow leaves and bark mulch everywhere and make it difficult to keep it clean.

First, bark mulch is not as effective as the wood chips I mentioned for a couple of reasons. Bark moves around in a strong wind and when blowers are used in the landscape. They float and move with water and rain.

Wood chips on the other hand lock into place because of their rough edges and don’t move around even if the wind speed is 60 or 70 mph. If wind is a problem, I would not use bark mulch unless you are willing to tidy up afterward.

Secondly, bark mulch is pretty, but it doesn’t improve the soil much. Wood chips disintegrate into the soil when moisture is present. In my experience, about half of it decomposes into the soil in about three years.

This disintegration supplies organic matter back to the soil. Bark mulch won’t do that. It resists decomposition. That’s why the bark in bark mulch comes from the outside of the tree while wood chips come from the inside of the tree.

Here’s how to make your roses happier and keep your rock mulch. Rake back the rock mulch 18 to 24 inches from your roses. Apply about ½ inch layer of good quality compost in this new area of bare soil and lightly mix it into the soil. Rake the rocks back into place and lightly water it in. You have now added organic matter to the soil and made the roses happier. Do this every two years.

If you have coarse rock mulch, you might be able to sprinkle the compost on top of the rock and just water it in. It can be messier than raking the rock back, but it will work this way and save time and effort. You will see improved growth from your roses in three to six months with either method.

Q: I planted the long Armenian cucumbers, and they came out so big and beautiful but so bitter. Why is that?

A: Armenian cucumber usually has fewer problems grown in the desert than cucumber varieties like Straight Eight and Marketmore. But cucumbers, in general, can get bitter with hot temperatures and when grown on the dry side.

Try mulching the soil (apply a thin layer on top of the soil) with wood shavings (horse bedding comes to mind you can get from a farm supply store) or shredded newspaper. This application keeps the soil cooler and moister. The old fruit might still be bitter right after doing this, but new fruit should not.

When growing Armenian cucumbers, they can get bitter if you don’t keep the soil wet while it’s producing fruit. But bitterness is less common in this species of cucumber than more traditional types.

Q: We have been growing fruit trees in Las Vegas for five years, and we want to grow about 30 to 40 fruit trees on some new property we bought. The area may have been sprayed with Roundup earlier this year. What do you recommend to neutralize or leach out the Roundup before planting the orchard?

A: The science behind Roundup says it does not persist long in hot weather and in our types of soils. It has an agreed-upon half-life of less than two months, and the longest half-life reported in research is six months.

I don’t think you need to do anything to the soil but prepare it for planting this fall and next spring. Any remaining Roundup in the soil will be nearly gone and be negligible by then.

The USDA Organic Program recognizes food production to be “organic” after the soil has not had any unapproved fertilizers, pesticides and soil amendments applied for the three years before and up to harvest. Because your fruit trees will not produce a substantial amount of fruit for about three years after planting, you are fine.

After three years of planting, if anything applied to the area meets the Department of Agriculture’s approved organic list, then anything harvested from these trees will meet the requirements for the USDA’s Organic Program.

Q: I have been living in Nevada for about one year and am originally from Utah. I saw that you are recommending windmill palm, but my landscaper with more than 20 years of experience was against it, recommending Mediterranean fan palm instead. What are your thoughts on the two?

A: Both palms do well here, but they fill different roles in the landscape. The Mediterranean fan palm handles hot locations better, but it occupies a bigger space and is more of a visual screen when unpruned. Windmill palm, on the other hand, doesn’t like the heat from west- or south-facing walls but has a single furry trunk; it’s narrower and open so you can see on the other side of it. Both are considered accent plants, look tropical and are good around pools and water features.

Where I see a problem with Mediterranean fan palm is when homeowners try to grow and prune it like the single-trunked windmill palm. Why not just get a windmill palm? The multiple furry trunks of the Mediterranean fan palm look nice when kept pruned annually. To me, that’s just more maintenance.

There is nothing wrong with windmill palm and growing it here. It is a cold-hardy palm taking temperatures down to 10 degrees. It may be a little harder to find in nurseries than Mediterranean fan palm and a bit more expensive.

Selection depends on what you want the plant to do for your landscape. If you want a palm that can handle hot locations and act as a visual screen, then get the Mediterranean fan palm. If you want a single trunk palm tree that requires little maintenance, get the windmill palm.

All palms like the soil amended at planting time and covered with wood chips, not rock. Water palms like any other tree or shrub of a similar size and with the same frequency.

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.