Mesquite tree roots need to spread

Here are some questions I worked on this week. Most of them involve irrigation.

Question: Why did my lush, healthy mesquite tree blow over?

I water it as instructed with an emitter at its base.

Answer: The key phrases here are "lush, healthy tree" and "emitter at its base."

With the emitters at the base of the tree, there is no reason for the roots to spread out in search of nutrients.

When the wind hit, the tree toppled.

With the roots still confined to the base of the tree, forget about trying to save it.

Q: Why are some of our Texas Rangers dying on one side?

A: You are only watering one side of the root ball.

Place other emitters around the plants and water longer at first to soak the entire rooted area.

Q: The southwest side of my California pepper tree has yellowish leaves.

Is this from excess sun exposure?

A: I suspect the roots are in a highly alkaline soil.

Place a sprinkler under the tree and drench the area in hopes of flushing away the alkali and iron to the tree.

Q: Do I need to prune my shoestring acacia? It is so weepy.

A: You are overwatering it and that is why it has so much excessive growth. Thin out the shoots, especially those loaded with fruit. Cutting back the water will control the growth.

Q: Where can we get some New Zealand spinach? We can't find it at the nurseries.

A: Master Gardener Helen Brown orders hers at www.stokeseeds.com. Brown plants her New Zealand spinach in the fall in rich soil with good drainage. She soaks the seeds overnight before sowing them. Space the seeds two feet apart because they become very aggressive. This particular spinach does not bolt, but keep it well-watered.

Q: I'm from back east and wondering why you never mention liming our soils?

A: Las Vegas soils are highly alkaline, which is the opposite of back there.

This ties up micronutrients plants need even though the elements are in the soil.

Sulfur lowers the pH and enables plants to access these special nutrients. Sulfur is slow-acting, so don't expect results for a while. Back east you used lime to raise your soil's pH.

Q: Can we grow citrus in Las Vegas? You seldom mention them.

A: We can, but we are on the edge of their frost limitations. Plant them in an area protected from those spring frosts that kill the fruit buds.

Going into winter, fruit buds are tight and will withstand lower temperatures. As it warms, they begin opening to become more vulnerable to frost.

Q: What is the white substance on my mock orange stems?

A: It's cottony cushion scale sucking sap from the bush. You'll find the insects underneath the waxy scales protecting them. Control them with insecticidal soap or a tree and shrub insect spray until controlled.

Q: Why is my 30-year-old Wonderful pomegranate not producing fruit?

A: Clean out the old wood so new wood can develop that will bear the fruit. It takes about three years for new canes to come into production.

This winter, remove a third of the oldest canes so light can penetrate the plant's crown to stimulate new growth.

In 2014 remove a third of the oldest canes you left in the bush to open it up even more. Also, select about five new canes coming from the crown and remove the rest. There will be lots of them.

In 2015 remove the final third of the older canes. Once again, save five new canes that came up that summer. It is during this year, that the five canes you select in 2013 begin producing.

It will be hard work but worth it. If you follow this process, you'll rejuvenate your plant every three years, and your reward will be a more productive bush.

Q: I transplanted nursery-grown okra. Why isn't it growing?

A: Don't waste your money on buying transplants of beans, cantaloupe, chard, corn, cucumbers, peas, squash and watermelons. They never seem to offer any advantages over directly seeding them in your garden.

Linn Mills' garden column appears on Sundays. He can be reached at linnmillslv@gmail.com or (702) 526-1495.