Cold damage should be left alone

Las Vegas had a couple of cold snaps recently. At the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas the low temperature hit 16 degrees Fahrenheit at
4:30 a.m. Jan. 15 while the high was 46 degrees Fahrenheit. Freezing weather can take several different twists depending on a few things.

First of all, a warming trend during the cold winter months can really mess things up for plants. They think it's spring, let down their winter guard and then - wham! - it freezes and they are taken by surprise. The plants sustain more damage than they would have if it had gotten colder more gradually.

If your plants were damaged and you can tolerate looking at them in that condition, let them go until you see growth in a couple of months. The presence of vigorous new growth will tell you where to prune and whether the plant was killed, or just looks like it . I will post more about winter freeze damage on my blog this week.

Q: I would like to grow rhubarb here in Las Vegas. I live in Sun City Summerlin at about a 3,300-foot elevation. Any and all info would be appreciated, such as variety, where to purchase, when to plant, shade or sun, in the ground or in pots, etc.

A: We tried growing rhubarb at our orchard a couple of times with no success. My guess is that it could not handle the heat . It is commonly believed that rhubarb will not grow in the Las Vegas Valley and the purported reason among gardeners is that it needs some winter "chilling." I am not convinced of this.

My failure should not stop you because I did not give it a lot of my time. It also was not planted in a protected area, which will require you to "baby" it for the first couple of years .

Rhubarb is probably not something I would recommend unless you are an experienced gardener and understand how to manipulate and manage your microclimates, soils and irrigation to get the response you need.

Your 3,300-foot elevation will help a lot compared with our 2,000-foot elevation at the orchard. It would be very happy at 4,500 feet or higher.

I would plant it in the ground. Find a bright but cool location that will protect the plant from late-afternoon sun. Light shade will work just fine. I would suggest the north or east sides of a building. Winter cold is not a concern.

Pick a spot where it can be left undisturbed for the next 10 years. This is a perennial crop; harvest stems regularly through the growing season.

Dig the soil about 18 inches deep and amend with about 75 percent good compost. There is a lot of junk compost out there. In compost, you will usually get what you pay for.

Rhubarb can grow to 4 feet in height in the right climate. You will probably see it healthy during the spring, look quite bad during the hot summer then rebound again in the fall. This is what we see with artichokes and other plants that are not supposed to grow here.

Plant the rhubarb rhizomes with at least one good "eye" pointing up, 3 feet apart, at about 3 inches deep. Fertilize with vegetable fertilizers. Mulch with straw to keep the soil cool and moist.

Place a basin around the plant to collect irrigation water and hand water it until you see strong growth. Fertilize it in January to get it started and lightly once a month when you are harvesting . The leaves are poisonous so just use the stalks or petioles.

Q: I planted about 30 pomegranate bushes two years ago. I bought them from a nursery and they told me that I was getting a variety of exotic species. But they had them in the nursery so long the tags were all gone. They are all thriving now and most have a fair amount of fruit this year. How do I determine when the fruit is ripe? Do they get easy to pick; do they nearly fall off the stem, or is that even a factor? Do the seeds need to turn red?

They are getting kind of leathery on the outside but most of those have seeds that really aren't red at all. They are still a little tart but that may be expected. A few are smaller and really red outside and quite red inside, but those are really bitter.

How do I figure out when they are ripe?

A: If we were all growing the same pomegranates, it would be a lot easier. But not all pomegranates mature at the same time and they do not all look the same when they do.

Some pomegranates are yellow on the outside, some are red, some are striped, and some are dark purple. Also, the seeds on the inside are not always red or dark red. Some of the prettier ones are, but not a variety such as Utah Sweet (which I think you may have).

It is a great variety but it does not look as pretty as the Wonderful variety, which is the most widely planted variety in the U.S. Some varieties, such as Utah Sweet, have seeds that are soft and nearly edible and, in some cases, people do eat them. Others, such as Wonderful, have seeds that are hard.

Some varieties have low tannin content and are not bitter, while some are quite bitter. Some have a delicate balance between bitterness and sweetness that many people relate to the true taste of a pomegranate.

Frequently, the fruit will separate from the tree with a gentle tug and twist when ripe. It is true, though, that if you know what variety you have, you can usually judge whether it is ripe by its color and the time of year.

Another way to tell if it is ripe is the calyx end or bottom where the "king's crown" is. When it flares outward, it is a good sign it is close to being ready.

Splitting of the fruit can be another indicator. If birds start to attack the fruit when it splits, that can be another indicator .

In any case, they are ready when you think they taste good. Start looking at them around mid-September, pick a nice-looking one and sample it. If it tastes good, look for some at the same stage of maturity and harvest them. Fruits harvested ripe off the tree can last a month because they are at different stages of development.

If not yet ripe, wait a couple of weeks and try another one. Keep going until you are satisfied you have the right timing. Mark it on your calendar .

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.