At each monthly meeting of the Houston Rose Society we have a section of the meeting called "Ask the Consulting Rosarian." Those who attend the meetings get to ask specific questions about their roses. For those of you who are unable to make the meetings, this column collects some basic questions I am asked as a consulting rosarian. I hope you find my experiences useful.
Question: Is it too late to plant new roses?
Answer: No. A rose purchased in a plastic pot already has a nicely established root system. You can plant such a rose at any time, so long as you are careful to not knock off the soil from the roots. Of course, spring is the usual time to plant new rose, and the selection is best at that time. But you can plant a potted rose in summer so long as you give it extra water. I recommend you hand water a rose planted in summer for five minutes or so, three times a day, for a couple of weeks. Then, gradually taper off the watering over the next three weeks. After that, treat the rose like all your other roses.
Also, do not fertilize your new rose for about six weeks. If you fertilize earlier, the fertilizer will be more than the new roots can handle. You may burn the feeder roots. Give the rose a chance to get adjusted to its new home before fertilizing. Water will be enough stimulant for the first month and a half.
Question: How many times a year should roses be pruned?
Answer: In Houston, we recommend pruning your hybrid tea, floribunda and miniature roses around Valentine's Day. Some rosarians prune again in early fall to get their roses ready for the fall rose show season, but the fall pruning is not necessary unless your are going to exhibit your roses. Old Garden Roses don't have to be pruned at all, except to keep them in bounds if they get too large. Climbing roses bloom on old canes, so don't prune them (if at all) until after the spring bloom.
Question: How much water do roses need?
Answer: Roses need lots of water, but they don't like wet feet. In Houston, we plant roses in raised beds so the roots don't get soggy. Our goal is to see that our roses get one to two inches of water each week, without drowning the roots. A rain gauge will help you determine how much help you are getting from mother nature. A water system or hand watering will let you make up the difference. Remember, just because it rained at the airport does not mean it rained the same amount (or at all) in your garden. Check your rain gauge to determine whether you have to add water to your rose beds.
Question: What is the spray schedule for insects on roses?
Answer: We don't recommend "preventative" spraying of roses for insects. Wait until you have a problem and deal with that problem. Most insecticides are contact killers. If you spray when no insects are present, you did not do your roses any good. And you might even harm the leaves if you spray in the heat of the day.
Fortunately, we have few bug problems on our roses in Houston. The biggest problems we have are with spider mites (in summer) and aphids (in spring). Both bugs can be controlled with a high-pressure blast of water from a "Jet-All" water wand. Hook the "Jet-All to the end of your garden hose and spray the undersides of the leaves. The spray knocks the spider mites and aphids off the plants and onto the ground. By the time they figure out what happened, they have missed their chance to reproduce. "Jet-All" water wands are available from Southwest Fertilizer (713-666-1744).
Question: Do I need a special kind of pruner to prune my roses?
Answer: I recommend a by-pass pruner, as opposed to an anvil pruner. A by-pass pruner works like a pair of scissors: the blades pass each other and slice the stem. With an anvil pruner the blade contact the blunt anvil portion which crushes the stem. Crushing, instead of slicing, may cause die back on the canes.
Popular pruners include Felcos and Coronas. Both are very good. Felcos are the choice of most rosarians because all the parts are replaceable, and because it is very easy to put on a fresh blade each year before spring pruning.
Question: Is there a good yellow rose for Houston?
Answer: Yellow roses are hard to manage in our heat and humidity. They look nice in the spring, but suffer the rest of the year. The general consensus of Houston Rosarians I have talked to is that St. Patrick's is the best yellow rose for Houston.
Question: My climbers don't bloom. What am I doing wrong?
Answer: There are two things to remember about climbers. First, they bloom on old canes. That means you don't prune them like you do a hybrid tea rose. If you prune them back to knee high, you will never get those old canes on which the blooms appear. Let those canes grow!
The second thing is that climbers bloom on horizontal canes. That means you need to let the canes get long and then bend them over till they are parallel with the ground. If you tie the canes to a fancy trellis so that the canes generally arch to a 45 degree slant, you will get most of your blooms at the tips of the canes--because that is where the canes are closest to horizontal.
My advise is to ditch the trellis and plant your climbers near a fence so you can bend the canes over and tie them to eye bolts where needed.
Question: Why do my white roses open up with brown discoloration?
Answer: The culprit is thrips. Thrips are tiny insects that suck on rose petals, turning the petals brown. You don't see this discoloration on red or pink roses, but it shows up clearly on white blooms.
You have two choices: live with the discoloration or spray a mild insecticide directly into the bloom just before it opens. The thrips are not on the whole plant, so don't spray anywhere except into the center of the soon-to-open bloom. Each bloom gets one spritz of insecticide. If the bloom takes a while to open, you may have to spray a spritz each day to make sure the thrips are gone. Organic gardeners use garlic spray instead of insecticide.
Question: I want to cut a rose to put in a vase. Is there a proper way to cut the stem?
Answer: There are a few simple rules for how to cut your roses. Your goals are to have nice roses for inside and to encourage more roses outside.
If you look at a rose cane, you will see that it has both three-leaf clusters and five-leaf clusters of leaves. To encourage new roses, be sure and make your cut just about 1/4 to 1/2 inch above a five-leaf cluster. That will cause the bush to put out a new stem and rose above that cut. For some reason, if you cut just above a three-leaf cluster the rose does not put out new flowers on that cane.
The next issue is how long should the stem be. Special guidelines apply for roses entered in rose shows. How long the stem needs to be varies with the class in which the rose is entered. In some classes the stem can be up to five times as long as the "height" of the bloom. There is no denying the majesty of a long stemmed rose. However, if you are cutting roses for the house, you don't have to follow that rule. You may want to cut a shorter stem so that the bush has lots of leaves to make more flowers.
Flowers on short or weak stems can be cut above the top five-leaf cluster on the cane. This leaves the maximum foliage on the bush. The rose can then be cut just below the bud and floated in water in a goblet to nice effect. This is a good way to enjoy your roses without cutting the cane way back.
Also, to maximize the life of your cut flower, cut your roses in the morning or at night instead of during the heat of the day. And have a bucket of water beside you so you can get them in water immediately.
Also, cut another 1/2 inch off the stem while the stem is under water in the bucket. Once inside, you gently lift the stem out of the water so that a drop of water clings to the bottom of the stem. Slowly lower the stem into the vase that you have previously filled with fresh water without knocking that drop of water off the end of the stem. The object of these maneuvers is to keep air from clogging up the veins in the stem. The drop of water keeps air from being sucked up into the vein of the stem. If air gets into the vein, the air acts like a plug and prevents the water in the vase from going up the stem, thus shortening the vase-life of your rose.
Question: How much sun do roses need?
Answer: Roses need at least six hours of sun per day. Anything less and they are leggy and weak, with few blooms. Shaded roses are more susceptible to disease.
On the other hand, roses cannot overdose on sunshine. They can take full sun, all day long. In fact, that's what they prefer. So find that sunny spot in your yard and fill it with roses!
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