Class to help turn thirsty landscapes into desert-friendly yards

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The new Desert Landscaping class is forming for fall, starting on Tuesday evenings beginning Sept. 13 from 6:30 p.m. to 8:30 p.m. for eight weeks. You will learn how to turn your old landscape or new landscape into a thing of beauty and usefulness and lower your water and electric bill. Pre-registering is a must, so you can sign up by calling our Master Gardener hot line at 257-5555. The class will be taught at our Lindell Learning Center near Sahara Avenue and Jones Boulevard.

I am looking for community volunteers for our new rose test garden to be built next year at our new university home in Henderson. This is a very ambitious project and to pull it off we will need as much help as we can get. The Demonstration Rose Garden will be located at Windmill Parkway and the Las Vegas Beltway at our new facility under construction. You don't have to know much about roses -- you will be taught! -- but you should have a burning love for roses because there will be lots of them! Call our hotline to find out more and sign up.

Q: My California fan palms are becoming too tall for the gardeners to prune on a regular basis. I am planing to hire a commercial company to prune them. When and how often should they be pruned?

A: The usual complaint by horticulturists about landscape maintenance people who prune palms is that they remove too many fronds at once. This usually results in the feather duster look. Palms need all the fronds that look good to manufacture enough sugars for energy. This might weaken the plant.

The reason they do this of course is the customer wants to prune as infrequently as possible to save money and by pruning severely like that you might be able to stretch another year between prunings.

When pruning, it is best not to remove more fronds than it would take for the canopy of fronds to make a half circle. In other words, it is best to remove only enough fronds so that the resulting canopy is the shape of a half circle. Avoid the feather duster look.

If you want to save money, then leave more dead fronds on the tree before you prune them again. It won't hurt the tree. The best time to prune is just before new frond growth in the spring, if the company is a feather duster maker, or just after spring growth, if they are not feather duster makers.

Consider removing lower fronds that are yellow or dead only. There is no biological reason to remove live green fronds on palms. There is no research supporting the notion that removing live green fronds reduces future pruning requirements. Do not remove green fronds or the palm could become stressed. If you decide to remove green fronds, do not remove those growing horizontally or pointed upward.

Q: Mesquite trees, 15 gallon size, were planted last year. They are now about 7-8 feet tall. I would welcome your recommendations for pruning to obtain maximum height and shade.

A: I guess some things I would not do might be a start. Do not prune large branches now. Wait for winter or very early spring. You can remove small branches now no larger than the diameter of your thumb or that you can remove easily with a hand pruner.

Do not remove limbs that expose the young trunk to our intense desert sunlight. Try to leave lower branches so that shade is created on the tree but high enough so that people and traffic can move under it without being impeded.

Do not make cuts that result in stubs or "dead ends." If you try to increase the height, cuts should be at a crotch so that when there is a cut made, the remaining branch is the longest one. This is thinning and you are removing the shorter branches so that more growth occurs in the longer branches.

If you were reducing the growth or height, you would prune out the longer and leave the shorter ones and you would leave lots of them so food for growth would have to be divided among many growing branches. Plant energy for growth moving down a branch will be more effective if it has fewer branches that can divide it up.

Don't start pruning at the top or removing small branches first. Start at the bottom of the tree and move up the tree when you are pruning. Remove the largest, unnecessary branches first and move toward the smaller branches later. You might spend an hour removing small branches on one large branch only to find out later that the large branch will be removed.

The fewer branches, the more energy and food each individual branch will get and the faster the growth.

Q: I have several vines of English cucumbers and at times they end up curling in on themselves. They look like circular cucumbers. It continues to grow just in a circle instead of straight. Any ideas why?

A: Curling of the fruit is probably due to incomplete pollination or fertilization of the flower. By fertilization in this case I am talking about the transfer of sperm from pollen to the ovules, future seeds in the flower that have not been fertilized yet.

If the plant produces female flowers and no fruit then this is total lack of pollination. This could be because of no pollinators, such as bees, or it could be just too hot for sperm to make it to the ovules. If you want to bother, you could try shading the plants in the morning when it is hot and removing the shade by midday. It might lower the temperatures enough to set fruit. But you have to provide openings for the bees to get to the flowers.

Cucumbers, as you have seen I am sure, have three locules or segments in the fruit. For the fruit to grow evenly, all of the ovules, or at least most of them, should be fertilized and have the potential to produce seeds. The seeds are needed for good development of the fruit.

Of course we pick cucumbers when they are immature fruits, before the seeds mature.

Take one of these fruits that are misshapen, or curved, and cut into it so you can expose the young seeds. They should all be the same size and shape. I am guessing that you will see undeveloped seeds, or few seeds at all, on the inside of the curve.

What can you do to prevent this? Usually the reasons are that not enough bees were present to insure good pollination, or it was too hot at the time of pollination, or there was water stress during pollination, or something damaged the young fruit. Make sure the cucumbers are mulched to conserve water and minimize the swing in soil moisture from adequate to too dry and back to adequate again. These swings in soil moisture might do it as well.

Growing cucumbers on the ground can also cause curling. Young cucumbers are growing so fast that if a stem or stick gets in the way, the fruit is forced to grow around it. Trellis your cucumber plants to avoid this problem.

Just for the record, bitter cucumbers are usually caused by stress, temperature, water, nutrition or all of the above. Usually when a plant produces bitter cucumbers you might as well get rid of the plant. It probably will not make anything but bitter cucumbers from that point forward.

Bob Morris is a horticulture specialist with the University of Nevada Cooperative Extension.