Weekly waterings should help plants survive through winter

: What advice can you give on winter care of a recently planted desert landscaping? I have lantana, Mexican bird of paradise, red fountain grass and others. What about fertilizing, pruning and frost prevention, if necessary?

A: The greatest challenges to homeowners with their recently planted desert landscape plants are finding the right amount of water to give the plants and surviving winter cold. Young plants are more susceptible to winter freezing than their mature counterparts.

As plants get older they typically become more tolerant and survive winter freezes better. This does not mean they will not get damaged, but that they recover better after being damaged.

Some parts of the valley will get colder than other parts. Some landscapes receive wind more than others. Even locations in some yards are more exposed than other parts of the same landscape. These are microclimates.

We have large microclimates in different locations throughout the valley. For instance, locations near the Las Vegas Wash will typically get colder than those in higher elevations. Developments closer to open desert frequently receive more wind than those downtown. So it is hard sometimes to give general recommendations, but the plants that you mention should survive the winter cold without too much trouble. The most cold susceptible in that group may be the Mexican bird of paradise.

As far as watering is concerned, they will need to be watered more often than established plantings. Once a week should be adequate this winter unless the soil is extremely rocky or gravelly. If you are unsure of yourself, buy an inexpensive moisture sensor that you would use for houseplants. A few days after an irrigation, insert the moisture sensor into the root ball and see what the moisture level is. Although these are not terribly accurate, they will give you a general idea of whether the soil is moist or dry.

After a few times of doing this you probably will not need to use it until spring and things warm up again. Do not fertilize until next February or March.

Q: My Arabian jasmine was doing so well. It had large, dark green leaves and produced big flowers continuously until a month ago. The leaves are yellower, it hasn't produced flowers the past couple of weeks, and today I noticed it had yellow leaves with patches of dark green. It has southern exposure underneath our patio and is being watered at 7 a.m. and then again at 8 a.m. for four to five minutes each time. I sent you a picture of the problem.

A: I am assuming that you know this plant will have difficulty in our climate. I hope it is not growing in rock mulch.

It is tropical and most likely will not survive the winter. It grows abundantly throughout Malaysia, Indonesia and the Philippines. It is a national flower of both the Philippines and Indonesia. The flowers are extremely aromatic and are used for making leis that are sold on the streets there as well as in Hawaii. The flowers are used for making jasmine tea. I personally love this plant but realize its limitations here.

This plant should be grown in protected areas of the yard so that it stays out of direct sunlight in late afternoons. The soil needs to be amended heavily. The picture looks like it shows some sun damage, but I am a little concerned because it should have shown up when it was hotter, not when the weather began to cool down.

Notice that the spots usually occur between leaf veins or along the edges of the leaf. The tan discoloration and partial leaf death on the one leaf looks very similar to drought and high light intensity. I do not believe it is a disease or insect problem.

I do believe it may be related to watering. I am sorry but overwatering or underwatering might contribute to this problem. Overwatering and dieback of the root system will cause the plant to be loose in the soil. Try moving the stem of the plant back and forth and see if the roots or the plant itself is loose in the ground. If the plant is loose, it is either because it was not planted correctly, it was too old in the container and root bound or it was overwatered.

If the plant is solidly rooted into the ground, then I would suspect underwatering. Make sure your drip emitters are not plugged. If it is the type of emitter that can be cleaned, then take it apart and clean it. Turn on the system and make sure it is dripping properly.

I hope this helps.

Q: We have a mature African sumac tree in our backyard, and most of the year the tree is absolutely beautiful. However during June, July and August it is the most awful tree around. The tree is constantly dropping yellow leaves and we are forever raking or sweeping them up.

A: African sumac grows extremely well in our climate, almost like a weed, and can reach 35 feet tall. It was introduced into the landscape industry in the desert Southwest. It is originally from South Africa. The tree can be a very beautiful landscape plant.

However, you have stumbled on one of its faults. The tree can be very messy. It also can shed a lot of pollen in late winter and cause some allergy problems. It also can shed seed from its berries and these seeds can start volunteers in the landscape.

Some people consider it drought tolerant. While it may be somewhat, it is not drought tolerant like the mesquites and acacias. So if you are putting it into a watering regime with other desert plants, then this may be part of the problem for you. It really will do best if put into the higher or moderate water use sections of your landscape. It does not belong in the driest part of the yard.

The faster you force it to grow, the more leaves it will shed. If you restrain its growth through moderate irrigations, then it will be less messy but it will not stop shedding leaves. All plants drop leaves. If it is excessive, try regulating your water and fertilizer applications to restrain growth.

If you cannot put up with some of these characteristics, you may have to replace it. I would do it now before it gets much bigger.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.