Flower proliferation

Seven of my ‘Smokin’ Hot’ hybrid tea rose blooms have buds coming out of the middle of the flower. All of these flowers are from the same cane which shot up from the very bottom of rose bush. I have never seen any other roses do this before.

I cut off these seven strange roses to the next five leaves. My question is whether I should remove the entire cane?

This is a genetic mutation called flower proliferation. The cause is not known; it can be triggered by late frost, insect damage, extreme heat, or sometimes by a virus. If your rose does this each year, it might be due to a virus. Usually, in roses, the next set of flowers that develops will not have this odd formation of buds inside it. If it does, you can prune back that shoot (the way you already did). This information from the Royal Horticultural Society explains the phenomenon. Local gardening expert Ciscoe Morris has this to say about flower proliferation:
“The condition is not caused by a disease, so if the affected flowers look bad, simply prune them off. The next flush of flowers that take their place should be normal. There really is nothing to worry about, however, so if any of the multiple-blooming roses look really cool, don’t be in a hurry to remove them.”

A related flower anomaly that can affect roses is phyllody, in which leaf-like structures appear in place of flower organs. When phyllody occurs repeatedly in roses, it can be a sign of disease.

Mutation, Rosa

Planting bare root roses

When should I plant bare root roses?

The Seattle Rose Society
suggests planting in March. The roses should be stored in a cool dark place if they cannot be planted right away.

Other recommendations include soaking the roots before planting (8-12 hours), and trimming off damaged or diseased roots. Try to maintain 3-5 canes per plant, and prune back to 3-5 buds per cane.

Dig a hole wide and deep enough to accommodate the roots. Make a cone-shaped mound of soil in the center of the hole to support the plant. Fill the hole 2/3 full of soil and add water to make a slurry–this gets between the roots. Do not tamp the soil. When the water drains, add more soil and repeat the water fill process until you reach the original soil surface (ground level).

Planting, Planting time, Rosa

Transplanting roses

I have a rose bush in the back yard, under a tree, it seems to be thriving but no one can see it blooming. I want to move it to a more prominent place in our yard. What is the best time of year for transplanting this rose?

Moving your rose out from under the tree is probably a good idea. Roses: 1001 Gardening Questions Answered by the editors of Garden Way Publishing (1989), says that the best time to transplant it to its new location is early spring or late fall. Before moving it, prune it, leaving three to four canes. Prepare the new hole in the ground (and) give it some extra attention after it is planted. This resource says that spring transplanting is preferred, because with warm weather on the way, the rose will have a better chance of starting new growth. When digging up your rose, dig a circular trench one foot away from the crown of the plant, removing the soil around the plant with your shovel. Loosen the root ball, and then take hold of the crown and push it back and forth to loosen it. Then lift it out of the hole. Dig a deep hole in the new location. Add two inches of compost, build a mound of soil, and spread the roots over it. Fill in with topsoil, make a ridge of soil around the base of the plant, and water well. Afterwards, water carefully, neither too much nor too little.

Rosa, Transplanting

Spacing for rose planting

I am using a Grandiflora rose named Prominent (Kordes) as a foreground planting; a climber (Autumn Sunset) is in the background. I love the color and the shape of Prominent’s blooms, but the blooms are sparse and plants are spindly compared to the healthy climber. Is there anything wrong with planting a new Prominent bush a few inches from each existing bush, to create fuller looking plants?

Below are some general guidelines on spacing for roses. Since you are planting a Grandiflora near a climbing rose which I am assuming has a structure to climb, you could probably get away with planting a bit closer than the 30″-36″ spacing recommended between two Grandifloras, but if you plant right up against the other rose, I imagine it would be problematic due to inadequate air circulation, which could lead to diseases. Here is what a publication of the University of Illinois Extension has to say:

“A general rule of thumb suggests that roses should be planted about 24 inches apart. This spacing will vary depending on the type of rose you are planting. Old garden roses will need wider spacing, while miniatures can be planted closer. Sufficient space between plants allows for good air circulation, an excellent first step in disease control.”

Suggested Spacing for Roses, from Jackson and Perkins:

Hybrid Teas & Grandifloras
Space: 30″ -36″ apart
Coverage: 6 -10 sq. ft.

Floribunda
Space: 24″ -30″ apart
Coverage: 4 -6 sq. ft.

English Rose
Space: 36″ apart
Coverage: 10 sq. ft.

Climber
Space: 4′ -5′ apart
Coverage: 12 -15 sq. ft.

Hedge
Space: 24″ apart
Coverage: 4 sq. ft.

Shrub
Large
Space: 30″ -36″ apart
Coverage: 6 -10 sq. ft.

Small
Space: 24″ -30″ apart
Coverage: 4 -6 sq. ft.

Miniature
Space: 12″ -18″ apart
Coverage: 1 -2 sq. ft.

Tree Rose
Standard
Space: 3′ -5′ apart
Coverage: 10 -15 sq. ft.

Patio
Space: 3′ -4′ apart
Coverage: 10 -12 sq. ft.

Miniature
Space: 2.5′ -3.5′ apart
Coverage: 6 -11 sq. ft.

Rosa

rose bush buds won’t open

I have several roses that bloom just fine but one particular rose bush produces buds that never open. Why is this happening?

It is possible that your rose has a problem with insects like thrips, which can cause buds not to open. If you see tunneling in the buds (holes in the petals), it could be caused by beetles. There is also a possibility that a disease is causing the problem. Fungal infections like botrytis blight can result in buds which do not open, but you would probably notice signs of the fungus during warmer temperatures, such as gray-brown fuzzy growth, and blotched petals or drooping buds. The Northwest Center for Alternatives to Pesticides provides information describing various rose problems, and organic solutions.

Here is a description of botrytis blight from University of California, Davis Integrated Pest Management. This is a brief excerpt:
“Botrytis blight, caused by the fungus Botrytis cinerea, is favored by high humidity. Affected plants have spotted flower petals and buds that fail to open, often with woolly gray fungal spores on decaying tissue. Twigs die back and large, diffuse, target-like splotches form on canes. Reduce humidity around plants by modifying irrigation, pruning, and reducing ground cover. Remove and dispose of fallen leaves and petals. Prune out infested canes, buds, and flowers. Botrytis blight is usually a problem only during spring and fall in most of California and during summer along coastal areas when the climate is cool and foggy.”

The Olympia Rose Society also has information on these potential causes of failed buds. Below is their description of thrips:
“Buds do not open, or flowers are deformed. Petals have brownish yellow streaks and small dark spots or bumps. White and pastel roses are particularly susceptible. Thrips (are) tiny orange insects with elongated bodies. Thrips feed at the bases of rosebuds and on the petals of open flowers. They seem to be attracted to light-colored blossoms.”

The Organic Gardener’s Handbook of Natural Insect and Disease Control edited by Barbara Ellis (Rodale Press, 1996) suggests encouraging natural predators of thrips and, if the infestation is severe, spraying weekly with a safer insectidical soap or pyrethrin-based product. This same resource suggests that if your roses have botrytis blight, you will see the buds turn brown and decay instead of opening, and you should pick off and dispose of any diseased buds. They recommend spraying with sulfur once a week during the growing season.

A few things that are always a good idea when growing rose:

make sure there is good air circulation around your plants
don’t water from above the plants (keep the leaves dry)
always clean up around the plants–don’t let leaf debris or any diseased buds lie on the ground under the rose bushes

This (now archived) site has many pictures of rose pests and diseases for you to compare with what you are seeing on your plant. Since I cannot diagnose the problem without seeing the plant, I recommend that you take samples of the affected buds to a Master Gardener Clinic.

roses to offer

I have several immature rose bushes, including some native Washington roses, that must be removed from my property. Are there any organizations, or individuals, who would be interested in transplanting them to another site?

You might want to check out the Seattle Rose Society website, which has lots of good information about roses.

You could also post your information about the roses, or reply to those seeking rose bushes, on the Pacific Northwest Garden Exchange on Houzz.

Another place that might have an interest in helping to find a new home for your roses is the adopt-a-plant list on the website of Plant Amnesty.

on low hazard pesticides

I heard somewhere that the fungicide Rose Pride was less toxic to beneficial insects than plain baking soda. Is this true? I’d like to continue to use it in my garden.

Rose Pride is the chemical Triforine. I was not able to find any articles which suggest it is safer for beneficial insects than baking soda. Pesticides Action Network’s Pesticides Database indicates it is toxic in varying degrees to some forms of aquatic life. It is on the PAN List of “Bad Actor” pesticides, which means it belongs to a group of pesticides classified as most toxic (because they are known or probable carcinogens, reproductive or developmental toxicants, etc.). The Extension Toxicology Network also has a profile for this pesticide. Here are excerpts:

“In the United States, triforine is marketed for use on almonds, apples, asparagus, blueberries, cherries, hops, ornamentals, peaches and roses. Triforine is a ‘restricted use’ pesticide (RUP) with an EPA toxicity classification of I (highly toxic). Check with specific state regulations for local restrictions which may apply. Products containing triforine must bear the Signal Word ‘Danger’ on their label.

Triforine and the formulated product Saprol are considered of low hazard to honeybees and to the predatory mite Typhlodromus pyrii. It is also of low hazard to earthworms at recommended dose rates.”

My comment would be that “low hazard” is not the same as no hazard, and since there are many other areas of concern with this highly toxic product, it would be best to find an alternative. Locally, the Woodland Park Rose Garden converted a pesticide-dependent landscape to an organic one, and the roses look better than ever. (See an article about the garden from the Seattle Times.) Many gardeners are learning to live with a bit of black spot on their roses, and manage the disease by maintaining good garden hygiene. Don’t leave fallen leaves on the ground. Give your roses good air circulation, and keep the leaves dry when you water your plants. Mulching with wood chips can help, too, since they may prevent water from splashing up onto the leaves.

When deciding whether to treat a garden problem with pesticides, the “Precautionary Principle” provides an important perspective:
“When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically.”

controlling rose sawflies

I think my rose leaves are being devoured by rose sawfly, and I was wondering if spraying ‘Rose Defense’ on them would help.

Rose Defense is a Scott’s product that contains Neem (as well as other ingredients). There is some evidence that Neem is effective against sawfly larvae. As with any pesticide, you should follow the directions on the package carefully (and note that this product may be harmful to humans, domestic animals, bees, and the environment, depending on the route of exposure).

You might want to start out with the least toxic approach first, that is, handpicking and spraying with water. Once larvae are knocked off the roses, they will not climb up again. If this doesn’t seem to be helping, then you could choose a Neem-based spray or insecticidal soap, keeping in mind that the Neem product is toxic to bees, and should not be applied when bees are active.

According to University of Minnesota Extension, sawflies are best controlled when young. You can simply pick them off by hand or dislodge them with a stick or a stream of water. If using water be sure to spray early enough in the day for the foliage to dry by sunset. This will prevent favorable conditions for fungal development. Horticultural oil, insecticidal soap and azadirachtin (sometimes called neem), are among the less toxic insecticides to treat young sawflies. Azadirachtin is slower acting. Bacillus thuringiensis (Bt) is effective on young lepidoptera caterpillars but NOT on larval sawflies.

Cornell University’s Resource Guide for Organic Insect and Disease Management also discusses the uses of Neem. Here is an excerpt:
“Neem products are generally sold as emulsifiable concentrates. Neem oil soap is sold as a water-soluble liquid concentrate. While Copping (2001) reports no known incompatibilities with other crop protection agents, phytotoxicity may be a problem when combining neem oil or soap products. Read labels for specific application guidelines including determination of re-entry interval and pre-harvest interval. Range of efficacy will depend on the susceptibility of species in question and environmental conditions at time of application. However these are points to follow:

Make multiple applications. Frequent applications are more effective than single sprays because neem does not persist well on plant surfaces. Like most other botanically derived materials, it can be rapidly broken down by sunlight and washed away by rain (Thacker 2002).
Use against immature insects. Azadirachtin-based insecticides act on immature stages of insects more effectively than on eggs or adults. To reduce a build up of populations it is important to make treatments to crops targeting insects in an early stage of their life cycle. For instance, neem would likely have little effect on an infestation of striped cucumber beetle adults; however if applied to potato plants early in the season, it has been shown to greatly reduce larval activity of Colorado potato beetle.
Begin applications before pest levels are high. Antifeedant and egg-laying repellant effects show best results in low to moderate pest populations.
Neem is reported to work best under warm temperature conditions (Schmutterer 1990).”

There are quite a few different species of sawfly, and I would guess that the rose sawfly is so named because rose bushes are its primary feeding ground. If you aren’t sure what is eating your roses, you may want to take samples of the affected leaves to your local county extension agent before you begin to treat the problem. You may find the images on the self-described Buggiest Rose Website (now archived) helpful in comparing with the leaf damage you are seeing.

Pruning roses

I would like to know when is the best time of year to prune back (heavily) the roses in my garden. I have read that winter is best, when they are dormant, but I have also read spring is the right time.

Also, with roses that are possibly 20 years old or more, and have very woody stems, is it all right to prune them back to the woody (brown parts)? Or should I not cut back past the green parts?

In the Pacific Northwest, most sources recommend pruning in late fall or early spring. Where to cut depends on the type of roses you have (modern, climbers, shrub, etc.).

The Seattle Rose Society also provides excellent pruning information.

You don’t mention what type(s) of roses you are hoping to prune, but the June/July 2011 Organic Gardening article by E.J. Hook, former gardener at the Woodland Park Rose Garden, covers basic pruning techniques for the 5 main types of rose.

growing roses in the Pacific Northwest

I would like more information on Rosa chinensis ‘Mutabilis’,
particularly regarding how it performs in a Seattle garden. I am most
concerned about black spot and any other diseases.

I am currently growing this rose for the first time, and it is blooming
profusely. I have needed to keep on top of the aphids (hand-squishing),
and there are a few yellowed leaves which drop (and which I have been
picking up and destroying as soon as I see them). Here is what the book
Roses for the Pacific Northwest by Christine Allen (Steller Press, 1999)
has to say about this rose:

Few old roses flower so continuously–cold weather merely turns the buds
a paler hue and, although they don’t then open, they remain fresh-looking
on the bush for weeks. It hates cold wind, but will take a surprising
amount of shade, forming an open, leafy shrub with soft red stems and
red-tinged foliage, impervious to disease.

I would not go as far as to say it is impervious to disease,
but my impression is that it is relatively disease-resistant. I am truly
enjoying the look and fragrance of this rose in my garden. Links to additional information:

An article by Valerie Easton in the Seattle Times