If planted too early, tomato plants will suffer from cold soils

Tomato plants that were put in the ground early, before this cold spell, didn’t grow much. This is because of cold soils. Cold air temperatures are bad enough, but when warm-season vegetables like tomato plants have “cold feet,” they struggle to put on any new growth, even with warm air temperatures. If they do get larger because of hot caps or Wall O’ Water plant protectors, it’s not because their roots got larger.

In cold soils, vegetables become purplish or darken in color because their roots struggle to take phosphorus out of the soil. Phosphorus is important for root growth and establishing transplants in prepared soils in garden beds. Adding more phosphorus to the soil doesn’t help. Only warm soil temperatures will.

Now is the time we transition our vegetable areas from cool-season to warm-season plants. Vegetables that take only four to eight weeks to finish are still fine; these include radishes, spinach and leaf lettuce, greens and even baby carrots.

They won’t interfere with one another. In fact, they help one another. Short-duration, cool-season vegetables can be planted between tomato transplants. A diversity of plants in the home garden helps keep pests and diseases at bay.

Q: My neighbor’s ash tree grew into their sewer lines, and because of the repair expense, I cut down mine. My HOA says I must replace it with another tree. I am looking for something smaller with less invasive roots. I’m thinking about a bird of paradise, blue chaste tree or a bottle brush? What do you think? My front yard faces west.

A: There are two things to consider regarding your question: why the tree invaded the sewer line in the first place and reasons for selecting a replacement plant. Any of your choices would be fine to fill a space, but ask yourself the purpose of this plant before making that decision.

In our desert, I don’t particularly like the idea of selecting a plant simply because it fills a space. Did this ash tree provide seasonal shade? On the west side of a home, this can be quite important for comfort and reducing electric costs for the air conditioning.

To improve comfort in a home and reduce energy costs, it is more important to shade the south and west walls of a building than it is the roof. The most “bang for your buck” in this regard comes from deciduous (those that drop their leaves in the winter) small trees or shrubs that don’t grow much taller than the building.

Smaller plants generally use less water than larger ones. Pick something that can handle the heat of a western exposure, drops its leaves in the winter and doesn’t get much above 15 feet tall if you live in a single-story residence and 30 feet tall for a two-story residence. Plant it a distance from the wall about half of its mature height.

The second issue is the invasion of sewer lines. This can happen with nearly any plant, but some are, rootwise, more aggressive than others. But roots need an opening or break in the line for this to happen. If the line is completely sealed, roots will not enter it.

Breaks in a sewer line are more likely if a tree is growing close enough so its roots crush it. Crushing a sewer line because of enlarging roots causes an entry point for roots to grow. Once this entry point is made, nearly any tree or shrub becomes invasive and plugs it.

Use irrigation to direct the growth of roots in desert soils. People who don’t live in the desert can’t use it to their advantage. Locate irrigation emitters on the side of the tree or shrub away from the sewer line.

Keep the area around the foundation as dry as possible a distance of at least 3 feet. As added protection, you might consider a commercial root barrier between the plant and the sewer line.

Q: Please give some tips on pruning my 3-year-old sweet lime tree: when and how often to prune, how tall to keep its growth on my limited backyard space and fertilizing.

A: Read most information on pruning of citrus, and it will tell you to prune citrus very little. Citrus of any type has few issues that need correction by pruning. They do not need to be pruned to improve fruit production like other fruit trees.

The primary reasons for pruning citrus are to reduce its size, remove problems like crossing and broken branches, and some thinning to reduce excessive growth.

They do need to be pruned if you want to keep them smaller. They can be pruned to backspace to about 60 percent of their mature size. But it should be done every year.

Prune just after harvesting the fruit so that it doesn’t interfere with next year’s flowering and fruit production. This also is the best time to apply fertilizer. Light pruning with hand shears and applications of fertilizer can be done any time of the year.

First, control its height. Identify backspace stems contributing to an undesirable height. These will be vertical or nearly vertical.

Follow the stems along their entire length, and remove them entirely at the point where they become vertical. This may be somewhere deep inside the canopy. It doesn’t matter if that’s the case. Remove them with a clean, close cut.

The tree wants to become tall. You want the tree to stay smaller. This is where you are at odds with the tree. You must control the tree; it should not control what you want.

The best production of fruit comes from stems that are not vertical. Consistent fruit production comes from stems that are near horizontal or no more than 45 degrees above horizontal.

If the width of the tree is a problem, reduce the length of horizontal or near horizontal stems. To do this, follow the length of the offending stem toward the inside of the tree. Remove the portion of this stem that is offensive at a juncture with another stem. Do not leave stubs.

Finally, remove any stems that are crossing or broken in the interior canopy.

Adding fertilizer to plants, particularly those high in nitrogen (the first number on the bag), should be done every year to maintain a high level of fruit production. But the amount applied should be adjusted according to the needs of the plant. If the tree is growing excessively, reduce the amount of fertilizer applied but don’t eliminate it.

Q: I want to put wood chips around my roses to keep the weeds from returning. Is this a good mulch for the roses? Or might it attract ants or insects I don’t want? I have not noticed wood mulch at any other homes nearby.

A: Roses and nearly all plants in the rose family, such as most of our fruit trees, thrive in our desert soils when wood chips are used around them. One of the biggest benefits, other than weed control, is soil improvement. And our desert soils need massive amounts of help in this area.

Mulch is applied to the soil surface around plants to assist in controlling weeds, improve the soil, reduce the frequency of watering, keep the roots cooler and to improve good animal life in the soil. The best mulch is made from shredding and chipping local landscape trees.

The greater diversity in types of trees used to make the wood chips, the better the chips are for the soil and plants. Personally, I don’t like wood chips made from palms and trees with large thorns, such as many mesquite trees.

Mulch is made from many sources. Anything applied to the surface of the soil could be referred to as mulch. This includes rock, gravel, sand, plastic, newspaper or old carpet, but the best mulch for soil improvement comes from a wide variety of wood chips.

Weeds are suppressed with a 3- to 4-inch layer of wood chips, but a few tough weeds will poke through, such as Bermuda grass, palm seedlings, nutgrass and well-established perennial weeds.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.