GARDENING: It's time to prepare plants for winter

Late fall is a wrap-up month. Most everything is centered on putting plants to rest for the winter, really cutting back on irrigations, mulching and sanitation. Getting rid of yard waste, preferably by composting, or disposing of it is important for disease and insect control for next year.

Generally, we don't fertilize any plants in the fall that might be sensitive to winter cold and freezing. Pomegranates will need consistent watering up until harvest to prevent fruit splitting. Allowing the soil to become excessively dry and then wet in cycles can cause the fruit to split.

Be careful when planting vegetable transplants and bedding plants. These small plants purchased from the nursery, called transplants, have been grown in small containers for several weeks prior to purchase. Their root system is often quite a bit smaller than the tops.

Ideally, in the established plant, we want the root system several times larger than the top. Quite a bit of catching up has to be done by that small root system. The idea in establishing these plants is to invigorate the root system so that it can enlarge and establish as quickly as possible.

You need well-prepared soil, unrestricted root growth, high phosphorus fertilizers, warm soil and adequate soil water and air. The soil should be prepared with plenty of decomposed organic matter (compost) and a starter fertilizer to encourage root development.

A dark, "fluffy" soil will be a warmer soil and enhance faster root growth. The root system in these small containers coming from the nurseries is jam packed with roots. They are very crowded and need a place to expand. It is important to gently separate this root system before planting so that it no longer is the same shape as the container.

This must be done quickly once it has been taken out of this small container. Some tearing of the roots is inevitable. Failure to do this will lead to stunted, slow-growing plants that will produce poorly, whether it's flowers or vegetables.

Question: Your comment about dwarf oranges in containers, please.

Answer: Dwarf Valencia and dwarf Navel sweet orange get to be about 10 feet tall.

Most fruit crops will produce fruit in containers, given time, good care, and adequate size and age. However, dwarf plants will produce sooner and be more productive than putting a full-sized fruit tree into a container. In the desert, extreme temperatures and irrigation become two of the most critical problems you will have to address.

Use as large a container as you can heft around. The roots are the most sensitive part of a plant in terms of temperatures. Larger soil masses and shading the container will help to insulate them. The soil needs to drain well, but be heavy enough to hold the plant upright in a strong gust of wind and hold enough water to last until the next irrigation.

Containers should be made of insulated materials -- materials that don't easily transmit heat or cold. Double potting, placing one pot inside of another so that the interior pot is shaded, would be helpful. Clay and wood pots need to be watered more often than glazed ceramic pots.

Roots in containers grow in different locations than they would if they were in the ground. Roots in containers tend to grow where moisture, air and temperatures are optimum. This is usually near the interface between the soil and the container, provided temperatures aren't extreme.

Citrus have a tendency, like the stone fruit, to die of root rot if their roots stay wet for too long. So, soils need to drain better than possibly some other types of container plants. Use a soil moisture meter to judge when to irrigate or the "feel" method, whereby you actually extract some soil with a probe and squeeze it to determine when to water. You need to make a soil moisture measurement at about midway down the container, not at the surface.

When growing fruit trees in containers, there is generally more care required than for fruit trees that are planted in the ground. Generally, fertilizing should be done more often, especially for citrus.

Any plants that are to be grown indoors part of the year should be acclimated by gradually reducing the light to which they are exposed for two to three weeks before moving them inside and vice versa for plants being moved outdoors. It is important that rapid changes in light exposures be avoided. For instance, plants growing in partial shade should not be suddenly exposed to complete direct sunlight. Such acclimation is not necessary for plants that are to be moved indoors for a few days during freezes.

Tropical and subtropical fruit trees cannot tolerate freezing temperatures for very long. Some will be killed back to the soil by mild freezes, while only small twigs will be killed on others. Some root damage can occur because the root system is not as well insulated from cold in a container as it would be in the ground.

Cold-hardiness depends on the plant, the care it receives and many other factors. Protection from severe cold is essential for all tropical and subtropical fruits growing in containers. Plants may be covered temporarily with blankets, paper or other material as protection against hard freezes, but such materials should be removed each morning to allow the plants to take full advantage of incoming solar radiation.

Plants moved indoors during cold spells should be placed away from drafts caused by doors and heating ducts. Other citrus that can be grown well in containers are Meyer lemons, kumquats, calamansi, Eureka lemons, and limes.

Q: Is blackberry the same as black raspberry? If they are not, how are they different in terms of cultural practices?

A: Blackberries and black raspberries are two very different fruits, although at the outside, they do look similar. Collectively, all of these types of fruits, those that are borne on canes, are called, cane fruit or brambles. If you remember, when you pick or eat blackberries, the center of the fruit has a full, white center. In a raspberry, that center is hollow and remains on the plant. That white center is the remainder of the flower, called the receptacle, which produced the fruit.

The two blackberries we are testing at the Master Gardener Orchard are two that performed best in Yuma, Ariz., called Womak and Rosborough. The only red raspberry that has performed much at all in southern climates is called Dorman Red, which we also have growing at the Orchard. Dorman Red has a low chilling requirement compared to other red raspberries, but has been reported to have poor to fair fruit quality. We will see how it performs in the middle desert.

A tayberry, interestingly, is a cross between a red raspberry and a blackberry. Fruit are very large, and the plant is trailing and very thorny. This cultivar is not cold-hardy in northern climates and so might be one to try in our southern desert climate.

Black raspberries initiate new canes from the crown of the plant rather than from root suckers. Because of this, they are grown in a "hill" system: each plant is grown independently, with pruning and maintenance done on a per-plant basis. They require summer tipping because individual canes will grow to unmanageable lengths.

Black raspberries bear their fruit in midsummer, and are the most winter tender of the raspberries. Purple raspberries initiate new canes predominantly from the crown, but may sucker between plants, as well. They are grown essentially the same as black raspberries, and have and intermediate chilling requirement, and both might be worth trying here.

Gold raspberries also are available, although they are not widely grown. Efforts are under way to develop a commercially viable gold raspberry.

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


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