Overzealous shearing inhibits growth

Master gardeners are now pruning at the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas. If you would like to see how we are pruning stone fruit, come out to the orchard either Tuesday or Saturday mornings from 9 to 11. Pruning on stone fruit trees continues through December. Apples and pears will be done in January. Grapes will not be done until March. For directions to the orchard, call the help line at 257-5555.

Q: I am writing concerning the slow decline of some bushes in our front yard. I believe the plants are from the cypress family. They have discolored, gaining more brown than green, especially on the inside of the plants. From my photo, you can see that they look as if a cancer has permeated their being; these plants seemed to have rotted almost overnight.

A: From the pictures, it looks like some Italian cypress and arborvitae. You are right; they are in the cypress family. Both sets of plants have been pruned with hedge shears. Brown patches are emerging through the canopy of the plants making them look pretty sad. These brown patches are the result of continual shearing and trying to retain the size and shape of these plants unnaturally smaller than they should be.

These plants grow fairly dense canopies when they are left unsheared. And they are big plants. If left unsheared, most of the green foliage is in the outer several inches of growth, perhaps even as much as a foot deep from the outside edge. Inside of the green foliage, the plant is brown and twiggy. The brown and twiggy growth is due to lack of light and age.

When they are sheared a few times, the canopy on the outer edges becomes denser while the inside brown and twiggy growth advances outward. Shearing retains the plant's shape and size by removing new and young green growth. Continued shearing prevents new growth from growing outward while the inside brown and twiggy branches continue to creep outward, unrestrained. This makes the green growth, and the places for green growth to occur, thinner and scarcer.

Sooner or later, the brown twiggy growth emerges through the canopy. It is most obvious right after a shearing. Even though the outer green edge is thin, spotty new growth makes the plant look unkempt. This causes whoever is doing the maintenance to shear it. Some parts of the plant grow back and in a week or two it starts to look like it is improving. Then, after another shearing, it looks bad again.

The problem is that these plants cannot be kept one size and shape forever. They want to get bigger and you want to keep them smaller. There will not be much of a compromise with these plants; they are just too large for your landscape.

There is not much you can do in this particular situation. It would be best if you remove them and start over. Landscape plants do have a life expectancy. They are not diseased or have pest problems. I take that back. The pest problem is the hedge shears. Personally, I would ban hedge shears from most landscapes.

Q: I planted some asparagus after I saw asparagus planted at the orchard. What should I be doing now that the weather is getting cold? Should I cut off watering? How do you treat your beautiful asparagus plants at the orchard?

A: I am hoping you planted your asparagus crowns deep, about 12 inches, and then added lots of compost over the crowns using about 4 or 5 inches of highly composted soil. We also put straight phosphorus in the hole when planting to help stimulate root and crown production.

After planting asparagus crowns, there should still be a shallow trench several inches deep above the crowns. You do not completely fill in this trench until late winter or early spring. The rest of the soil added to the trench should be heavily amended with compost or aged manure.

During the summer, we deep watered the asparagus about once a week. Sometimes they were watered twice a week when it was really hot. During this past growing season, we added nitrogen twice after mid-August.

Now that it is getting colder, we are not adding any fertilizer to the asparagus. We want it to go to sleep. Adding more nitrogen will delay the onset of winter dormancy. Normally, the fronds will start to die back now because winter is approaching. As soon as the ferns die to the ground, we will cut the top growth down to the ground.

During the winter, we will irrigate it enough to keep the soil moist. Allowing the soil to dry too much will damage the crowns and growth for next spring. You can use a soil moisture meter to help you to determine when it is getting too dry; they cost less than $10 at your local nursery.

Push the meter into the soil so that the tip is close to the depth where the crowns are located. Irrigate when you see the meter enter the dry part of the moisture scale or get near to it. If you used enough good quality compost or manure, you probably will not need any more fertilizer until late summer or so.

By the way, you can harvest asparagus spears anytime they are thicker than your pinky. You should leave spears thinner than that alone and let them form fern-like growth. Thin spears are popular now but you need experience growing asparagus before you start selecting how much of the thin spears to remove and how much to leave behind.

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 extremehort@aol.com.