Fertilize woody shrubs, trees this month

Don’t put fertilizers too close to the trunk. They should be close to wherever you have water being applied for irrigation. Let the water push the fertilizer into the root zone for you. Either dig a shallow hole near the water source and put these fertilizers into the hole and cover it up or use a shovel to accomplish the same thing. A shovel easily can be used to put the fertilizer in the right location by irrigating first and then, when the soil is wet, pushing the shovel into the soil a few inches and pushing it forward. Drop the fertilizer in the open slit in the soil, then remove the shovel and push the slit shut with your foot.

Of course, an easier method might be to use fertilizer stakes. Pound them into the wet soil with a hammer using the plastic cap so they don’t break apart. It is not as messy and there is no broken fertilizer bag with which to contend.

Q: I am growing canna lilies and the leaves are burning on the edges. The pot is now full. Can I divide the canna? When is the best time to do this?

A: This is most likely a soil and irrigation problem. I don’t think it is a problem with the type of canna lily you have. I do not know any variety of canna that will not grow in Las Vegas. One of my favorites is Tropicana because of the leaf color as well as the flowers. I have had them in full sun in a south-facing location and they have done well.

It is best if they are not close to a very hot wall, but grown out in the open. They will not do well in a desert landscape but should be grown in the part of the yard you have chosen to be wetter.

Since you are growing them in a container, use a large container - the larger the better. Small containers in the sunlight will overheat in our climate, cooking the soil and plant roots in a very short time. If you cannot use a large container, then double pot your existing container so that it nestles inside a larger one and shades the smaller one.

Cannas should be divided (separate the rhizomes with a sharp, sterile knife) in the fall (October) every three to four years and repotted with freshly amended soil at that time. If they are grown in the ground, make sure the soil is amended each time you replant. Amend the soil with compost and a phosphorus fertilizer, either something like DAP or bone meal.

When planting the rhizomes, put several in the container, spaced 12 to 18 inches apart, depending on the variety of canna and its mature size and spread.

Irrigate so the soil stays moist; but it should not remain wet. There is a difference between the two. If you are not sure of the difference, buy a soil moisture meter. They are inexpensive at the nurseries and garden centers.

When irrigating, it is very important that the soil is leached or washed free of salts monthly as damage from accumulated salts also can cause leaf scorching as you describe. Las Vegas water coming from the Colorado River is high in salts. So run a couple of gallons of tap water through your container monthly making sure the soil drains well.

The container should be in a location to receive eight hours of sun each day, if possible. Morning sun is better than afternoon sun, but full sun also will work with adequate ventilation and some distance from a hot, south-facing wall.

Q: Why does my pomegranate fruit have yellow seeds?

A: Your yellow seeds may be because of a couple of things. First of all, if it is a variety of pomegranate that never gets dark red arils (the seed and pulp inside the fruit), then it will never turn dark red. There are varieties that do not. There is nothing wrong with this. It is just the characteristic of that particular pomegranate.

Another reason may be that the fruit was picked immature and is not yet fully ripe (you picked it too early). Pomegranates that are harvested too early will have “seeds” that will never develop a normal, full dark red color. In this case, the fruit also will never develop its full sweetness and flavor since pomegranates do not ripen any further once they have been harvested.

In any case, the earliest I have seen early-ripening varieties of pomegranates fully mature is in early September. If you do not know the variety of your pomegranate, then start harvesting fruit about a week to two weeks apart starting in early to mid-September. The latest the fruit should be harvested might be mid-to-late November, but before any hard freezes.

Q: We have two peach trees that are 7 years old. This year the peaches on both trees tasted bitter.  I don’t recall doing anything differently. One of the trees produced bitter peaches the year after we planted it but has been fine until this year. Do you have any thoughts on this?

A: You don’t mention if the peach is a miniature or not. There is variation on the quality of fruit produced on trees from year to year and much of that is has to do with the weather during the growing year.

For instance, this year our early peaches and even our early apricots did not have the same quality in flavor because of our unusually cool spring. And they did not ripen evenly . Many of our fruits trees need to have consistently warm or even hot temperatures during development to get good flavor and high sugar content. Otherwise, they can be bland or worse.

I have also noticed that miniature peaches, such as Bonanza, produce fruit that can be variable in quality from year to year. It is nothing you did and there really is not much you can do about it.

Bob Morris is a horticulture expert living in Las Vegas; he is on special assignment in the Balkh Province, Afghanistan, for the University of California, Davis. Visit his blog at xtremehorticulture.blogspot.com.