GARDENING: January means time to finish pruning fruit trees

You should be finishing up your fruit tree pruning this month, making dormant oil applications, painting the trunks and lower limbs with diluted white latex paint or whitewash and fertilizing.

You could start tomato seedlings over the next couple of weeks or start them directly from seeds into your own garden by first putting clear plastic over the prepared area and warm the soil via the sun for a few days. Plant directly under the plastic and make sure it is sealed to the soil by covering the edges with earth and pinning the plastic to the soil. You can just use 3 or 4 mil plastic used for polyethylene tarp.

Once they germinate you have to get them protected by something like a Wall O' Water or hot caps but leave them under the plastic as long as you can. Cold weather may stunt warm season vegetables like tomatoes and peppers.

We are not done with the cold weather yet so leave any damaged plants due to freezing alone to see what is alive or dead. Pruning of grapes and roses is usually delayed until later in the winter. Normal pruning and fertilizing of trees and shrubs can be done at any time now.

We still have lots of mulch at the orchard in North Las Vegas. Come and get it.

Question: I have a question on watering cacti during the winter. I can find no authoritative answer as to when to water these types of plants during winter months. Most books I have just say water when dry, but my neighbor who also has a number of varieties of cacti said not to water these plants from December through February or March. I don't want to lose any of my cacti so I'm hoping you can answer the question for me.

Answer: This is not an easy question to answer. I have been chastised by Dave Turner of Dave Turner's Nursery and Greenhouse for not giving a better answer in the past. It's easy to just say to people to treat cacti all the same but they can be very different if you get into some of the more exotic types.

Not all cacti should be watered the same. Some can go longer between irrigations than others. Most importantly, they all need good drainage. I would not go all winter long without irrigation unless they are established for at least one year in the ground and they are native to dry desert regions. Otherwise, I would water them just like your other desert plants that are trees and shrubs.

A suggested schedule might be every other week to three weeks apart. I would use a soil moisture meter that you can buy from a nursery for about $8, put it about 1 foot from the drip emitter or other water source and water when the meter indicates it is dry.

You probably need to find out where the plants' native habitat is located and the type of climate there. From that you can determine how dry you can allow the soil to get before watering. An excellent place to look up different cacti and succulents and their general care is the Tucson Cactus and Succulent Society's Web site at www.tucsoncactus.org/ and use their plant database.

Bottom line, all cacti are different but generally speaking low in water use. The secret is to water deeply, widely and infrequently and spread the water out to a distance of a few feet from the plant.

Q: While pruning my dwarf apricot, I noticed black discolorations along the bark of many of the branches, particularly around the buds. The tree had many aphids this fall that I just washed off with water. It reminded me of fire blight I had seen on pears. A neighbor has a badly infested pear tree with fire blight. My pears are OK. What do you suppose it is?

A: It is not fire blight most likely. Fire blight is a very rare occurrence in apricot. If the branch and growth seems healthy then I am guessing it possibly is normal discoloration of limbs due to age.

Oftentimes branches darken and may have a sooty appearance that can be rubbed on to your fingers. Pears are a different story. I would look at some other apricots to see if there is the same discoloration. It could be normal. I will post a picture of fire blight in my newsletter for those interested.

Q: A few months ago I purchased a split-leaf phylodendron plant and now it is limp. I only water it every 10 or 12 days, and I put it outdoors when it is warm, thinking the sun would help. All the leaves are very green and look healthy, however, they are all limp as of a week ago. I thought I should cut it in half and repot the cut plants to new containers with fresh soil. They are very compact in the original pot and I think they are root bound and do not have any air. Any suggestions?

A: When putting a tropical indoor plant outside just remember that these plants can be damaged easily by temperatures below 55 F, direct sunlight and even light winds so make sure they are protected. When inside plants are taken outside they are very easily damaged by extremes.

I am confused about why it might be limp. The obvious reason is that it might not be getting enough water but I am sure you thought of that. What would happen if you gave it water more often and repotted it with soil that holds more water? When the entire plant is showing problems the problem is frequently in the stem or root system.

So let's cover the basics. The plant should not be in direct light but it should be in a room with very high indirect light for several hours a day. When you water it should be water that you know is not softened. Some houses have their entire plumbing system on soft water including outside hose bibs.

The soil should be kept moist and not dry out if you want them to grow. The best way to check for soil moisture it to lift the pot after watering and then every couple of days until you can let the weight of the container tell you if it needs water. Otherwise you can use a water meter you can get at the nursery for about $8. The soil should not go dry on this plant.

For rapid growth, fertilize lightly every couple of weeks. This would be a dilute application of fertilizer in your normal watering. Make sure water drains out the bottom of the container at each watering. Once a month run water through the container to flush out salts.

You can use reverse osmosis water or distilled water but you should add some minerals to the water such as one-quarter to one-half teaspoon of fertilizer per gallon. Pure reverse osmosis water can be damaging to soils since it contains no minerals at all and can cause it to lose its structure unless it is very porous.

Q: Many years ago, my mother used to put a sweet potato or yam into a glass of water and very soon it sprouted lovely green leaves and before long it was a charming plant.

Last week I tried this with my grandchildren and nothing happened. Not having done this for over 50 years, I don't remember if there was secret trick I have forgotten. Could you please clue me in? My grandchildren are so disappointed that nothing is happening.

A: Make sure the fat end is up and the pointed end down or you can cut the sweet potato in half and do the same thing. Orient the cut sweet potato in the same vertical direction as if it weren't cut. Up is up and down is down for a sweet potato regardless of whether it is cut or not. Roots come from the pointed end and leaves from the fat end. Change the water daily. Keep it warm, above 70 F.

I would recommend this publication from Cooperative Extension at the University of New Hampshire on kitchen houseplants ceinfo.unh.edu/Pubs/HGPubs/hpkitchn.pdf.

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