Grafting different plant on rootstock can produce multicolored flowers

A: I wish we could declare it a miracle, submit it somewhere and have a party. Unfortunately, it probably isn’t. What makes this observation even more interesting is that Lady Banks rose comes in two basic colors: yellow and white flowering selections.

On rare occasions, a totally different plant can grow from a mother plant. This is called a “sport” in horticultural terms. These are genetic abnormalities — a mutant, if you will. Most mutants are not valuable, wasted time in evolution, but sometimes they can be valuable.

One example is the nectarine. The fruit from a nectarine tree is basically a hairless peach. The tree is identical to a peach tree. If this hairless fruit had hair on it, we would call it a peach.

The first nectarine ever was found by a farmer growing as a sport from a peach tree. Mutants like these can give rise to totally new types of plants that can become important commercially. If it weren’t for this observant farmer, we wouldn’t have nectarines today.

Back to your situation. How did these white flowers suddenly appear on a totally yellow plant? Unfortunately, the explanation is probably quite simple and not very miraculous.

Lady Banks rose is grown commercially by grafting the Lady Banks part, called the scion, onto a different rose plant used for its roots, the rootstock. This rootstock is a totally different kind of rose flower, but its roots have desirable characteristics that can contribute to the survival of the scion plant.

In your particular case, the scion, the yellow Lady Banks rose, was probably grafted to Rosa fortuniana, a white rose commonly used for its very desirable traits as a rootstock.

Rosa fortuniana shows excellent resistance to nematodes and a great deal of tolerance to poor soils. It is a very common rootstock used for roses planted in southern climates of the United States.

These white flowers come from a sucker growing from this white rootstock rose. As it gets older, this sucker produces white flowers, quite a bit larger than flowers of the yellow Lady Banks, but an excellent rose in its own right just the same.

You can prune these white suckers from the mother plant and keep it totally yellow or let these suckers grow and have a beautiful combination of white and yellow flowers on the same plant. Some pruning may be required to achieve a balance in growth between the two roses so that one does not dominate the other.

Q: I have been very pleased with the wood-chip mulch I got from the University Orchard and am using around my fruit trees. I need more of it in larger quantities. Can you recommend where I can get it?

A: I started using local wood chips as a surface mulch around fruit trees back in the late 1990s at the University Orchard in North Las Vegas. I agree. The health of the trees when wood-chip mulch is used surrounding them is like the difference between night and day.

Wood chips slowly decompose into the soil surrounding these trees over two to three years, dramatically improving desert soil.

These wood chips are sourced from local trees rescued from landfills. They are recycled rather than buried in the desert. I do not allow palm trees or mesquite wood in this mulch mix because of the dangerous thorns of the mesquite and the difficulty in getting palm wood to decompose.

The benefits of using wood chips as a surface mulch around fruit trees and landscape plants will be seen the first year after it’s implied around the trees.

These wood chips can be picked up free from the University Orchard in North Las Vegas or the Cooperative Extension office just south of the airport. For more information, call the master gardener help line at 702–257–5555.

The primary tree company in Las Vegas responsible for this effort is First Choice Tree Service. It is worth giving them a call to see if they can deliver it in large quantities.

Q: You mentioned increasing “how often to water” rather than the “number of minutes” as the growing season changes. When are these changes made and how often?

A: Irrigation schedules can be important, but they also can cause problems if some flexibility in this schedule isn’t followed when the weather isn’t cooperating. This cool, wet spring was the perfect example.

Scheduling irrigations should follow a seasonal pattern that increases the frequency of applied water as the season moves from spring to summer to fall. This is much easier to do than guessing the number of minutes of applied water to use.

The concept of an irrigation schedule is sound, but some hands-on judgments should be applied when irrigation changes are being considered. These judgments help fine tune a schedule around unseasonal weather conditions.

Knowing how much water is remaining in the soil is a critical hands-on judgment. It is impossible to look at the surface of the soil and know how much water is around the roots.

What I have found valuable is a heavy-duty soil moisture sensor. The one I like has a 24-inch stem and can be purchased online from stores like Amazon for about $70.

Using a soil moisture meter to help gauge when to irrigate is a skill that can be developed. Once developed, knowing when to water becomes intuitive. Remember that the moisture sensor is located at the tip of the probe, and measure soil moisture in three or four locations around the plant.

Think of the soil surrounding fruit tree roots comparable to the gas tank of a car. After an irrigation, the “gas tank” is full. When irrigating plants, refill the gas tank when it is about half empty. The meter on the probe helps knowing when to irrigate again.

During the winter months, fill the gas tank infrequently. During the summer months, fill the gas tank more often.

The following is a basic fruit tree and landscape tree and shrub irrigation schedule that can be adjusted with a soil moisture meter: early February (once per week); late April (twice per week); late May (three times per week); late August (twice per week); late October (once per week); mid-December (10 to 14 days).

Q: In early February I moved a small ruby red grapefruit tree into a half barrel full of prepared soil. I made sure the roots did not dry out when I moved it. I pruned the top back best I could. What leaves were still on eventually fell off. It is slow to put on new growth compared to my other citrus trees.

A: Your tree is experiencing transplant shock. No matter how careful we are when moving a plant, roots get torn, they dry out, and the roots must readjust to their new environment. Sometimes these adjustments are minor. Sometimes they are major. Major adjustments take longer to recover.

Once moved, the new plant must take some time to repair these torn and damaged roots before it can resume normal growth again. If these adjustments are minor, transplant shock is hardly noticeable. If these adjustments are major, it can cause long delays in resumption of new growth, or the plant can die.

How quickly the tree recovers depends on how it was pruned after moving it. Shearing the entire plant causes the tree to recover more slowly. Selectively removing branches helps the plant recover more quickly.

Most likely your tree will recover soon. Make sure the tree is staked so the roots don’t move. Keep the soil moist but not wet to minimize root rot.

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.