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Tuesday, February 5, 2013

What Do I Do About Freeze Damage to My Plants?

From what I heard, Las Vegas had a couple of cold snaps. At The Orchard in North Las Vegas the low temperatures hit 16F at 4:30 am on February 15th while the high was 46F. Freezing weather can take several different twists depending on a few things.

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

            If damage occurred to your plants and you can tolerate looking at them in that condition, then 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, but it isn’t. I will post more about winter freeze plant damage on my blog this week.

Figs Dying Back During Winter Months

Fig with late spring freeze damage on the tips and leaves
Q. I have a backyard orchard in Henderson with 14 fruit trees planted similar to what I have learned from the Dave Wilson videos and the UNR orchard. This is my 3rd year and I should be getting a decent amount of fruit. My problem is the figs. Two years in a row two fig trees have died to about 3-4 inches up the trunk. Last year I replaced both trees with new Kadota and Black Mission figs purchased from the nursery in pots. The new trees have apparently done the same thing. The trees are planted on the NE property line, so they get full afternoon sun. We had a very mild winter....I don't really understand what is going on here.

A. I am not sure what is going on either. If you are in a particularly cold part of the valley you could be getting some winter kill. It is not just the minimum temperature that matters. If low temperatures hit out of season (November or early December or mid February) they can't handle the low temperatures they could normally handle in December and January.

The important points in planting figs would be the same as the other fruit trees; add compost to the backfill at planting time, make sure it is planted the same depth as it was in the container, stake it the first year, it does not have to be whitewashed so don’t, keep the rabbits from it as they LIKE figs and will kill them, water them the same as other fruit trees, mulch them with wood mulch but keep the mulch away from the trunk 12 inches the first four seasons until established.

Do not water directly next to the trunk but at least 12 inches away. Do not fertilize directly next to the trunk or you can kill them. They can be damaged by very cold winters, more so than apples or pears. I hope this helps.

Rhubarb? In the Hot Desert?

Q. I would like to grow rhubarb here in Las Vegas. I live in Sun City Summerlin at about 3300ft. 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 did try rhubarb at our orchard a couple of times with no success.  It could not handle the heat, primarily, which is my guess.  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.

            But my failure should not stop you because I did not give it a lot of my time and it was not planted in a protected area which it will require to “baby” it for the first couple of years until you learn how to manage it.

            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 3300 foot elevation will help a lot compared to our 2000 foot elevation at The Orchard. It would be very happy at 4500 feet or more. I would plant it in the ground.

            Find a bright but cool location in your yard that will protect the plant from late afternoon sun.  Light shade will work just fine. I would usually 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, harvesting leaves and stems regularly through the growing season.

            Dig the soil about 18 inches deep and amend with about 75% 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 four feet in height in the right climate. You will probably see it healthy during the spring and fall and really look quite bad during the hot summer months then rebound again in the fall. This is what we see with artichokes and other plants that are not supposed to grow here as well.

            Plant the rhubarb rhizome with at least one good “eye” pointing up, three feet apart, about three 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 until you see strong growth. Fertilize it in January to get started and lightly once a month when you are harvesting the leaves and petioles. The leaves are poisonous so just use the stalks or petioles.

Navel Oranges? In the Cold Desert?

Q. We have a question about our 5- 6 year old naval orange tree. For the past 2 to 3 years we left the fruit on the tree until the weather man said freezing temperatures were coming. But with just cold nights, the fruit seems to dry out. Can we pick the fruit early and let the oranges ripen in the house?

A. Just a note. Navel oranges are real tricky here in southern Nevada. They have to be planted in just the right microclimate or they will freeze. I forwarded this question to my counterpart in Phoenix, Terry Mikel, for a response.

            Navel Oranges tend to be a bit persnickety especially when they are young, no matter the cold, heat or whatever.  If you are seeing lots of leaves and small branch damage, then frost will be an issue.

            Freezing nights will dry out any citrus fruits. The juice inside freezes and crystals rupture cell walls and the juice simply drains out. The problem with citrus, if the fruits aren't ripe on the tree, they won't ripen any more off the tree. Sorry.  

            There is another possibility and I am hoping that the 'damage' is due more to being juvenile and not as much due to freezing damage. If the leaves aren't hurt by the freeze, then the fruits wouldn't be either. As the plant gets more mature, there will be more “metabolism” going on and thus better fruits.

When Do I Pick This Pomegranate? I Don't Know What I Have!

Some pomegranates have wonderful color inside like
this 'Wonderful' pomegranate
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, like 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 really quite red inside, but those are really bitter.

So the real question I am asking is - 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 not all look the same when they do.

Pomegranates can come in a wide range of colors
            Some pomegranates are yellow on the outside, some red, some striped, some dark purple. Also the seeds on the inside are not always red or dark red. Some of the prettier ones are but no a variety like Utah Sweet (which I think you may).

            They are a great variety but they do not look nor are they as pretty to look at as the Wonderful variety which is the most widely planted variety in the US. Some, like Utah Sweet, have seeds that are soft and nearly edible and in some cases people do eat them. Others, like Wonderful, have seeds which are hard.

Some pomegranates may tend to split when they are ripe
            Some have low tannin content and so are not bitter at all while some are quite bitter. Bitterness is an acquired taste and in some cultures is preferred. Think of the bitterness in beer or bitter melon. Some have a delicate balance between bitterness and sweetness that many people relate to the true taste of a pomegranate.

            Some ripen by September while some ripen near Halloween.

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

            Another way is the calyx end or the 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 they split that can be another indicator. Ground squirrels may also attack the fruit.

            In any case they are ready when you think they taste good. Start looking at them around mid-September and pick a nice looking one and sample it. If it tastes good, then look for some at the same stage of maturity and harvest. Harvesting 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 in your calendar. Take pictures of the mature fruit, send it to me and let me see if I can help you identify it.