GARDENING: Planted wisely, oleanders tough enough to withstand cold

A series of monthly evening seminars on backyard and small-scale fruit production starts this month and runs through February. For more information and a calendar of events, e-mail Extremehorticulture@unce.unr.edu or contact the master gardener hot line at 257-5555.

Question: Is now the best time to plant the oleanders? Are the plants that you can buy this time of year sufficiently unstressed to plant successfully? How and when should I prune the oleanders?

Answer: Now is the best time to plant most plants, including oleanders. Oleanders are tough plants and will take most stresses without even flinching. Just make sure that when you plant them, they are replanted into the ground at the same depth as they were in the container. Oleanders have very few plant pests and are not responsible for most of our allergy problems here.

Secondly, put an irrigation well around them so when you hand water them with a hose during the first couple of weeks, the water has a place to stay around the plant and really sink in deep. After that, they can survive on whatever irrigation system you have provided. They are not low-water-use plants, but will respond to water with lots of growth and increased density.

Remember that most dwarf oleander are not as cold-hardy as their bigger cousins, the standard forms. They may be damaged or killed at temperatures in the low 20s.

The best time to prune them is just before new growth in the spring. Take out a quarter or a third of the plant every two or three years. Select the largest stems and cut them off at ground level.

This will cause new shoots to form and fill in at the base and give you a show of flowers from top to bottom as long as you don't use hedge shears during the rest of the year.

Q: I am a new resident in Las Vegas. I have four fruit trees -- apple, pear, peach and fig. I can't tell the different seasons that you have here. When do I spray the dormant oil spray? When should I give them fertilizer? Can I use the tree spikes? Will the trees' leaves drop off?

A: Our winter months are December until about February. Our spring can be long some years, like from early February until May, and then very short to nonexistent other years. These years, the winter months kind of melt directly into the heat. Fall is from the end of September until December.

I would use your trees to gauge your seasons in this case. Winter is when the leaves are gone. Fall is when the leaves are turning and beginning to fall. Spring is when they are blooming and leaves are beginning to emerge and new growth starts. All of the leaves will fall at least when we get temperatures near or below freezing.

Usually, this should be any time from November to about Dec. 15 and possibly later if we have a warm winter. All this can change depending on the weather for a particular year.

All of the fruit trees you mentioned should receive dormant oil just before leaf emergence, which is just around bloom time, depending on the plant. I would estimate you will apply your fertilizer and dormant oils starting at about the same time, the end of January. You should apply lightweight dormant oils, the type in the nursery, every two weeks until the weather approaches 90 degrees Fahrenheit; not during bloom, though.

You can use fertilizer stakes if you want. They work well and are convenient if you have just a few trees. Be sure to use enough.

It is important to mulch your fruit trees with organic mulch several inches deep, and it should extend at least to the drip line or ends of the branches. Fertilize lightly again after you harvest. The fig should have plenty of foliage covering the fruit, or you may have lots of fruit drop until it does.

I would prune back some of the ends of the branches facing the south and west to produce more leaves and shade the fig fruit. This will eliminate the early fruit produced at the beginning of 2005 on those sides pruned, but you would still have fruit produced later on branches produced in 2005. Many figs have an early crop and a later crop.

Q: How long do I water my new 15-gallon trees and plants before I can cut back to a few days a week? My landscaper says I have to water them every day for at least two weeks and then cut back. Is this true?

A: The plants should be watered in with a hose the first few times to settle the soil around the root system if you haven't done this yet. If it is planted correctly in the first place, this step is unnecessary.

It will help if there is a basin around the plants to hold a larger volume of water, unless you run the water around the plants very slowly so it sinks into the ground. This, of course, means you will have to move the hose around to each plant if you don't have a basin. Frequently, there is no basin around plants watered with a drip system.

You really don't have to water daily for two weeks unless you think the soil is not a good soil and may contain high salts. Watering frequently, like it was suggested, also will help remove salts from the soil and is a general safety precaution if damaging salts are present.

Right now, I think you could get by watering them two or three times a week initially, as long as they are not desert plants, and as long as they were soaked really well a few times at the beginning. Desert plants, of course, can go longer between waterings, but it is important to water thoroughly and deeply each time, regardless of whether they are desert plants. Then hold off until the soil begins to dry around the root ball before the next irrigation. This may be twice a week in summer, to every 10 days or longer in winter.

If these are on drip irrigation, 15-gallon plants should receive about 8 gallons of water each time you water, and there should be at least three emitters per 15-gallon plant.

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


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