Garden Answers

Roses

When should I prune my roses?
Do I really need to mulch my roses over the winter?
Do you have any instructions on when and how to transplant roses?
What is this white film on my hybrid tea roses and how do I get rid of it?
My rose petals edges are almost black and buds don't open. Is it too hot for my roses to bloom?
Why does my rose plant look anemic and speckled and dry?
What should I do to get my roses ready for the winter?
Should I hire a professional to prune my roses?
What is the correct way to get starts from an existing rose bush?
What should be used to seal pruned ends?

Question: When should I prune my roses? I believe they are all Hybrid Tea. This is our first spring in this house and there are 48 rose bushes. I read somewhere that if I prune too early they may revert back to the pre-hybrid. Thank you for your help!

Answer: It's still a little early to prune your roses in February. The reason is that roses are "dumb" plants. You see, a plant's natural response to pruning is to push out new growth to replace that which was lost. Roses take that to an extreme. Pruning them too early can result in a flush of soft, succulent growth that can be damaged or killed by late frosts. You're best to wait a little bit before pruning. I usually recommend pruning the first part of April, usually between the 5th and the 10th of the month. One little trick I've used is to let the plant tell you when to prune. Look at the canes a foot or so above the ground. Don't look up at the top of the plant. Those stems are probably starting to sprout now or will be soon. Look down low. When the buds there have pushed out about three quarters of an inch go ahead and prune the plant.

I like to prune my roses back pretty far-usually down to a foot or so off the ground. Remove any dead or damaged canes, and remove any older, larger (1" or bigger) canes to make room for younger, more vigorous canes. Keep five to eleven canes to from the plant. They should be evenly spaced around the plant, and angling out away from the center of the plant. Remove any crossing or competing canes. You want the finished shape of the plant to be an upside down cone with the center empty. Cut the remaining canes back to 12" to 18", cutting just above an outward facing bud. You're trying to open the plant up, make it more spreading. This will improve air circulation within the plant, cutting down on powdery mildew problems later this year. The last thing to do is to paint the ends of the canes with pruning paint to prevent cane borer from getting into the plant. Hope all this helps.

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Question: I've heard lots of talk about mulching roses. Do I really need to mulch them over the winter?

Answer: I think that it's a good idea. While we've had fairly mild winters for a while now, mulching is good, cheap insurance. I just know that the one time I decide against it, old man winter will zap my roses and they'll suffer some significant die back. This is the time to mulch your roses now that the ground has started to freeze. Basically, mulching your roses means putting a mound of mulch about a foot high that covers over the graft. A course mulch works best, so look for materials such as chopped leaves, wood chips, straw, or cedar mulch. Avoid a fine mulch, like grass clippings, because it gets matted down and doesn't allow for good air circulation. Come spring, when you start seeing new growth, remove the mulch and you're ready to go!

If you have a shrub rose, you probably don't need to worry about mulching them. Most of them are not grafted, that is, they are growing on their own roots. If we had a cold winter and the plant froze back to the ground, it would sucker back from those roots, but it would be the same plant you started with, not some strange, mutant, "wild" rootstock sucker that would have to be removed and replaced.

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Question: Hi, We live right here in GJ and want to know if it's okay to transplant rose bushes in May. Some friends don't want theirs and we want to plant them in our yard. Also, do you have any instructions about doing it?

Answer: This really isn't a good time to be transplanting roses or any other plant for that matter. Plants are actively growing right now, and transplanting now will damage or destroy a very significant percentage of the roots, no matter how careful you try to be. This is a shock to the plant, and can sometimes lead directly to its loss. More commonly, the plant will survive initially and try like mad to regrow the roots it lost (which takes some time). The problem is that our climate doesn't give the plant the time it needs to reestablish. In a month we'll be much hotter and dryer, putting a lot more stress on the plant, for which it's unable to cope, and from which it often doesn't survive.

Now, having painted this gloomy picture, if your neighbors are anxious to be rid of their roses, and you want to give it a try, you really have nothing to lose. However, if you have the luxury of time, and your neighbors are willing to wait, the best time to be transplanting is early spring, sometime in March usually.

Here's how to transplant: First, dig the holes in your yard where the roses will be going. You want them to be good and wide, but they don't have to be that deep. I would guess they should be 10" to 12" deep and 18" to 24" wide. You'll probably have to adjust them once you get the roses over to the hole. Next, you want to dig up your neighbor's plants. I'll work around the plant in a circular pattern with a shovel, digging straight down to cut the roots, forming a root ball 12" to 18" in diameter. Don't pull back on the shovel yet, just push it straight down into the ground to cut the roots. The bigger and older the plant, the bigger the rootball needs to be. Actually, the bigger the rootball, the better chance of survival your new plants will have. You'll have to balance your desire for the bigger rootball against how big and heavy of a plant you can handle!

Now you want to dig a circular trench or "donut" with the circle you've already made as the inner part of the donut. Once you've done that, gently and patiently work your shovel under the rose to free the rootball. Once it's free, I think it's a good idea to support the soil ball by wrapping it with some burlap or an old sheet. Pull it tightly around the rootball and pin it together with nails. You don't want the rootball to crack or break apart while you're handling it. Move it over to the hole you've prepared in your yard and place it there. You want the top of the soil of the rootball to be an inch or so higher than the level of the soil in your yard. At the very least, it can be level with your grade. You may need to adjust the hole by digging out or filling in soil. Be sure that the soil in the bottom of the hole is well firmed so the plant doesn't settle once you water it. You want room between the outer edge of the rootball and the edge of your hole. This gives you room to work and provides a space to put amended backfill.

Once the hole is properly adjusted, and the plant is set into the hole and placed just the way you want it, remove the burlap or sheeting. Backfill around the plant with a mixture of 1/3 Soil Pep or Peat Moss and 2/3 soil that you dug out of the hole. Firm it gently around the plant. Use any extra soil to form a basin around the plant to hold water (we have these instructions on our website or come in and we will give you a sheet on how to plant shrubs). Fill the basin up with water so that you get three or four inches of standing water so the rose is soaked thoroughly. After the water has soaked in, give it a second soaking, but this time use a solution of Fertilome Root Stimulator mixed with water according to the directions.

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Question: I have an ugly white film over my hybrid tea roses that comes off if I scrap my fingernail over it. What is it and how do I get rid of it?

Answer: Sounds like powdery mildew, a common problem on roses at this time of year. How are your roses watered? They often get mildew when watered by overhead sprinkler systems. If you're able to avoid that, they'll be happier with being watered from the bottom. If not, there are several things you can do to help keep them from getting powdery mildew as well as options to take care of the problem once you have it.

Consider the timing of your watering. Powdery mildew is often the result of an extended period of humidity. Here in the valley, the humidity usually rises from midnight to sun-up. Watering in the evening (before midnight), extends that time of high humidity and leaves your bushes more susceptible to mildew. If you have an automatic watering system, watering as early as 2 am is okay because you're not extending that high humidity time and won't loose as much to evaporation. If your system isn't automated, watering right after sunrise is a good idea. You're not extending that period of high humidity and still are taking advantage of the cool of the day.

Pruning is also an important part of keeping your rose bush healthy. Roses thrive on having good air-circulation throughout the bush. Cut back all dead canes, and remove crossing or competing canes. What you're aiming for is shaping your rose bush like an upside down cone with no branches in the middle. (Difficult to explain without an illustration. If you stop by the nursery we have a Gardening Guide that would help.)

While modifying your rose's environment is a great help, once you have powdery mildew there are several ways you may choose to treat it. The most organic of these is to use an Ultra Fine Oil Spray. A word of caution here: Be careful when using this product when the temperatures are 90° or more. They have the potential to burn the foliage when it's too hot. Many folks will test a little area of their plant first to be sure it doesn't harm the leaves. When using such a spray, the trick is to thoroughly cover your rose bush. Be to coat both the tops and bottoms of all the leaves. A second organic choice is to use sulfur . It works well, though not during the hot days of summer. Using this product on hot days (90°) will scorch your leaves. Another spray which works very well is a fungicide that contains the active ingredient Triforine. We usually have people spray two times at ten days apart. In some cases a third spray is necessary to get rid of the problem. Hope this helps.

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Question: The edges of my "Mr. Lincoln" rose petals are almost black. Some buds don't even open. Is it too hot for my roses to bloom?

Answer: No, rose blooms will slow down in our intense heat, but it doesn't damage the blossoms like that. It sounds like you have a problem with thrips. Thrips are tiny insects that live in the buds of plants. Their direct feeding damage is minor, but it gets magnified as the bud expands. What you're seeing on your roses is typical browning or blackening of the petals, or in severe cases, a failure of the bud to open.

To be sure you're dealing with thrips, cut off a bud and tap it over a sheet of white paper. You can often knock some of the little monsters off the flower and onto the paper. Look closely. You should see some tiny (1/32" long), torpedo-shaped bugs running around. If so, man the torpedoes-I mean-spray with Ortho Isotox or Bayer Rose and Flower Insect Control three times at ten-day intervals.

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Question: I have a rose plant that looks anemic. The leaves are speckled and dry. What's going on?

Answer: You probably have a tiny problem, literally-spider mites! Spider mites are almost impossible to see with the naked eye. You can tap a suspect leaf over a sheet of white paper, knocking specks of dust onto the paper. If some of the specks start moving, those are spider mites. However, the only sure way to verify spider mites are your problem is to spot them with a hand lens.

The problem with spider mites isn't their size, it's their numbers. Their populations can quickly explode until there are zillions of these little monsters, and you get damaged plants. Spider mites suck plant sap, causing the speckled, silvery, and dried appearance you've noticed in your rose.

Controlling spider mites isn't that hard, but it takes some persistence. The best material to use is Kelthane, although Isotox, Bayer Advanced Garden Rose and Flower Insect Killer, Diazinon, and Insecticidal Soaps give adequate control. You'll want to spray three times at seven-day intervals.
One little trick that will give you better control of spider mites is to give the infested plant a hard shower with cold water before you spray. Do this in the evening, and then spray the following morning when it's cool.

If you're interested in a less toxic way to help control spider mites, give your plants a shower. Spray infested plants with a hard spray of cold water, concentrating especially on the undersides of the foliage where most spider mites congregate. You'll need to do this every day or two for two or three weeks. It may not completely eliminate the mites, but it can reduce their numbers to manageable numbers.

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Question: What should I do to get my roses ready for the winter?

Answer: Please keep in mind that roses are stupid plants. They don't know when to stop growing. With any encouragement at all, they'll grow late into the fall, making them prone to frost damage. Because of that, there are several things to do (or not do!) this fall. First, don't fertilize roses this time of the year. You should not fertilize your roses after the first of the August.

Another thing to do is to start backing off of the frequent watering schedule you had during the summer. You can encourage the rose to enter dormancy by drought stressing the plant a little. Obviously, you don't want to go too far and hurt the plant with too little water.

Mulch the rose to protect it from the bitter cold temperatures we'll get later this winter. Place a 12" tall pile of coarse and loose mulching material (such as straw, cedar mulch or chopped leaves) over the base of the plant to protect the graft union. Many people want to do this too early in the fall. Mulching shouldn't be done until the ground freezes and the plant is fully dormant-usually in late November. Mulching too early holds in the warmth of the soil, keeping the plant growing later into the fall than it should. You'll want to remove the pile of mulch when the plant starts to bud out in the spring.

Late November is also the time to consider a little light pruning. If you have a plant that is excessively tall (five feet or more), giving it a rough "crew cut" down to three or four feet will neaten up the plant and reduce the chance of snow loads breaking off canes during the winter. The traditional pruning of roses should wait until late March to mid April.

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Question: The thought of pruning my roses really makes me nervous. Should I hire a professional to do it?

Answer: Save your money! There's nothing to be nervous about. Just follow these simple steps for a beautiful and healthy rose bush.

Before I tell you how to prune your roses, let's be sure they're ready to be pruned. Look at the buds twelve inches above the soil. If the buds have pushed out one to two inches long, it's time to prune. Ready?

The first job of pruning is to remove dead, damaged, or diseased canes. This can be a little difficult to determine, because some varieties have canes that turn brownish during dormancy. if you're not sure a cane is living, scrape off a small patch of bark. A living cane will have white or green tissue.

Select 5 to 11 canes to keep. These will form the base of the rose plant. The goal is to form an upside down cone with an empty center by cutting away all other canes. The canes should be evenly spaced around the plant's center, angling outward. The plant needs to be open to insure good air circulation. This will help avoid powdery mildew later this summer. Choose good-sized, sturdy canes. Old, large, woody canes usually don't grow or bloom well and should be removed in favor of a younger, more vigorous cane.

Now that you've made your choices, it's time to cut. The pruned rose bush should be twelve to eighteen inches tall. Cuts are made just above an outward facing bud. Use sharp pruners.

The final step is to paint the cut ends with pruning paint to prevent problems with cane borer. You really don't want these nasty little bees and wasps digging into your perfectly formed rose bush.

Check out our planting guide for roses for illustrations to help with pruning and other maintenance jobs.

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Question: How should I water my roses?

Answer: What you want to do is soak the plants well when you do water, but then allow the soil to dry a little before soaking them again. The best thing for you to do is to dig down into the soil every day or two and check the soil for dryness. I like to look at the soil down three or four inches. It should be moist, but there should be some dryness showing as well. Don’t let the soil get bone dry at that depth—that’s too dry! When the soil has reached that point, soak it WELL.

Watering every day (or nearly so) is simply too much. For established plants (which yours are now), I’d figure on giving them a good soaking every five to ten days. I give the roses in my yard a good soaking once a week.

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Question: What is the correct way to get starts from an already existing rose bush?

Answer: The best way to get starts from an existing rose is to take cuttings of the plant. We have a page on our web site that tells you how to do it. Go to http://www.bookcliffgardens.com/answercenter/pg-cuttings.htm to see it. I would suggest doing softwood cuttings and the best time to do them would be next spring. May would be the time I'd choose. You want to have fresh, green, succulent shoots to cut. 

I have to warn you: roses are one of the tougher plants to root out. Because of this, do more cuttings than you think you'll need. You're bound to have some failure so this will help cover that.

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Question: I just pruned my roses and was going to seal the ends with the icky black goo.  I was talking to a Master Gardner who said she believed there was now a different recommendation on what to use - she thought it might be Elmer's white glue? Have you heard that too?

Answer: It’s always a good idea to seal the cut ends of your rose canes to prevent problems with cane borer later this spring. The little borer enters the soft pithy end of the cane and will usually kill the cane down as far as it tunnels down. It’s easy to see if you have this little bugger—there will be a nice round hole in the end of the canes. The sad part about it is that the damage is unintentional. These little wasps or bees are not eating the rose; they’re just digging out an egg chamber. In fact several of these guys are actually beneficial as they parasitize plant pests like Aphids and they can be important pollinizers of different crops. The best way to avoid their damage is to prevent them from tunneling into the cane in the first place. Placing a physical barrier on the cut end will keep them out of your rose. They can only get in through the soft pithy center; they can’t bore in through the side of the cane.

I’d still stick with the old black tar pruning paint. Elmer’s Glue works fine as a barrier, but it doesn’t last; it breaks down in the sun and the moisture and will have to be reapplied. It’s easy to apply the goo to the ends of the cut canes early on before they really start growing; it’s a lot harder to do it after they’ve shot up a lot of growth. You have to reach down inside that dense, THORNY plant to put it on. The pruning paint is waterproof, so it will last and last.

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