Growing Roses: The Queen of Flowers

Rose Gardening

Home gardeners have been growing roses for well over 2,000 years. Loved for their beauty and fragrance, they are cultivated for a variety of landscape effects or for cutting. The members of the genus Rosa are prickly stemmed shrubs with a wide range of heights and growing habits. There are as many as 150-200 species and thousands of varieties, from miniatures (6 inches to 2 feet tall) to climbers that may grow 20 feet or more. Perennial.

Site Preparation

Roses like a good, well-drained soil and will grow best in protected spots with ample water and full sun. Plants require at least 8-10 hours of sunlight per day for optimum growth.

Tip: If you have a choice between morning or afternoon sun, it’s probably best to choose morning. This will help dry morning moisture from foliage quickly and prevent many plant diseases.

Planting Bare Root Roses

Planting from bare root stock is ideal because the plants adapt to your particular type of soil much better than those planted from containers. Also, bare root plants are much more economical to purchase and there is more variety at the nursery.

Keep the bare root plants damp until planting time. Dig a large hole, make a cone of rich potting soil at the bottom. Add some fertilizer to the soil mixture. We like to use a mixture containing bone meal, greensand and glacial rock dust. Place the rose in the hole with the roots fanned out over the cone. It is important that the grafted section of the stem is not buried below the soil. Check for depth, then gradually fill in the hole with a mixture of the native soil and organic compost. Water immediately after planting to settle the roots in place. Wait to fertilize until you begin to see new growth. December-April (depending on location) is the best time to plant from bare root.

Planting Potted Roses

For a new site, dig a hole, which will vary depending on the size of the container, approximately 1 foot deep and add a nice layer (approximately 4 inches) of compost, well-aged manure or peat moss. Also spread on fertilizer. We recommend a blend of bone meal, greensand and rock dust. Dig this into the soil, mixing well. When planting, make sure that the grafted section, or bud union, of the stem is not buried below the soil. Check for depth, then gradually fill in the hole with a mixture of the native soil and organic compost. Water immediately after planting to settle the roots in place. Do not fertilize until you see new growth.

Transplanting Mature Roses

The ideal time to transplant roses is when they are dormant in winter or early spring. If you must move rose bushes during the growing season they will be put under considerable stress. First prepare the new planting site; you never want the roots to dry out. Next, prune the top growth so the plants are easier to handle. Then dig as large a root ball as you can handle and move the plants to the prepared holes.

Don’t worry if you break a few roots, the reduced top growth will not require as many roots for support. Be very careful not to damage the trunk or branches during transplanting; injuries open the plant to invasion of fungal disease and insect pests. Water immediately after transplanting. No fertilizer until you begin to see new growth.

Tip: To help prevent many fungal disease, water on bright sunny mornings, to allow the leaves to dry by evening.

Mulching

A 2-4 inch layer of organic mulch will help deter weeds, improve the garden’s appearance and prevent moisture loss. Be careful to leave several inches around the stem of each plant un-mulched.

Note: As mulches decompose they use up soil nitrogen. Watch closely for signs of nitrogen deficiency and apply appropriate fertilizers, if necessary.

Fertilizing

Roses appreciate an application of slow release fertilizer in spring, midsummer, and again in the fall. Use organic fertilizer and add a tablespoon of chelated iron to the dry mix. Apply the fertilizer mix around the base of the plants, dibble it into the soil and water well.

Pruning

The ideal time to prune roses is when they are dormant. The purpose of pruning is to improve the health of the plant and control the shape.

First, remove any leaves that remain on the plant.

Next, cut out any dead, diseased or injured wood. Look for branches that are different in color to determine if they are dead. Usually dead branches are brown or black, but sometimes its just hard to tell. One sure way is to cut off a bit from the tip of the stem. Is it green inside? If so, then it is alive. If the stem is brown inside, that means it is dead.

Roses need excellent air circulation. Remove any branches which cross through the center of the plant. Those will inhibit vital air circulation once they grow leaves again in the spring. Make sure to remove them as close as possible to where they grow from. If you leave a stub, new growth will form there. One way to get close is to place the blade of the pruning shear flat against the stem.

The next step is to prune for shape. The ideal shape for a hybrid tea, grandiflora or florabunda rose is a vase shape. Picture in your mind an octopus with his legs slightly spread at the bottom. Now, turn him upside down. That is the shape you want for your finished pruned rose. The remaining stems should be 10-15 inches long, depending on the size and variety of the rose.

There is one more thing – each of the remaining stems should have the growth bud facing out. This is sometimes impossible to accomplish, but can be achieved after a few years of pruning. Buds are distinguished by a slight scar or line on the smooth green bark of the rose.

Old garden roses need to be pruned individually. Miniature roses just get a general all over buzz cut. Shrub roses should be groomed and trimmed back to fit their environment, but no heavy pruning. After pruning, rake up any fallen leaves from under the plant. Insect pests over winter in debris. Finally, spray with a Bordeaux mixture (copper and lime) or a lime/sulfur spray to kill any over-wintering insect eggs.

Pruning Climbing Roses

After planting a climbing rose, leave it un-pruned for 2 or 3 years. It takes a while for the plants to become established. During this period, do general grooming and remove all dead, diseased or injured wood and the spent flowers. Tie new canes into position on a trellis for support. In a few years, the plant will consist of only long canes and from these branches, you will get the laterals that produce flowers. Varieties differ in how they produce canes; some throw out new canes each year from the base of the plant while others build up a more woody structure and produce new canes from higher on the plant. Your objective should be to encourage new growth of the flowering laterals and to stimulate production of new canes.

For annual dormant pruning, remove only the old and unproductive wood. Then, cut back to two or three buds and all of the laterals that bore flowers during the preceding season. Canes that grow in the wrong direction should be trained, and removed only if they are uncooperative.

Winterizing Roses

Where winter temperatures fall below 10 degrees F. roses need winter protection. The last fertilizer application should be timed so that the plants will stop producing flowers by the first projected frost date. The last crop of blooms should stay on the plant to form hips which will signal the plant to stop growth. The plants should remain well watered until the soil freezes. After a few hard freezes, mound soil over the base of the plant to a height of 1 foot. Dig soil from another part of the garden, not from around the roots of the rose. Cut long canes back to 2-4 feet and tie them together with twine to prevent wind damage. When the soil mound has frozen, cover the canes with evergreen boughs, straw, or other material. This will prevent the mound of soil from freezing and thawing. You can remove this protective cover in spring when you are fairly certain that good weather has arrived.

Insects and Diseases:

There are numerous insect and disease problems associated with roses (too many to mention here). Below we have listed several of the more common problems:

Mites

These tiny insect pests do their damage by sucking juices from surface tissue, causing yellowed, dry looking leaves that sometimes show silvery webbing underneath. Mites are almost invisible. Defoliation can result. To control, spray dormant oil or lime-sulfur on dormant plants. During the growing season, use insecticidal soap with pyrethrin for control.

Rose Bud Borers

There are two destructive insect pests that bore into rose buds. Rose curculios are 1/4 inch, bright red, black beaked insects. Rose leaf beetles are 1/8 inch, shiny blue or green insects. Both of these pests bore into flower buds, preventing them from opening. Handpick if possible, or use insecticidal soap with pyrethrin to prevent the spread of these destructive pests. Also remove and destroy infested buds.

Rose Chafers

Rose chafers are an insect pest that chew holes in rose foliage. Hand picking is the best remedy, but any botanical insecticide will also work. Make sure to mix the spray with a little horticultural oil so that it sticks to the leaves and is there when the critters come to dine. Otherwise, it may wash away in the rain. Pyrethrin is an organic insecticide made from chrysanthemums.

Leafcutter Bees

Cleanly cut holes in the foliage, either round or oval, suggest the activity of leafcutter bees. After damaging the leaves, these pests bore into the stems and canes to lay their eggs, causing wilt. Control by pruning out the injured tips several inches below the damaged area. Seal the cuts end of the cane with grafting wax or putty.

Botrytis

A fungal disease which makes the unopened buds appear rotted and gray. Pick off and destroy diseased blooms and spray plants with micronized sulfur spray to control. Provide excellent air circulation, and keep the area beneath the plant clean to prevent reoccurrence.

Powdery Mildew

Roses are especially prone to powdery mildew. It is a fungus disease that makes the leaves look as if they have been dusted with talcum powder. It is not especially damaging to the plant, it just makes them look ugly. Avoid overhead water if possible and keep the area under the plant raked up and clean. Don’t plant anything under your roses to increase air circulation. Water only in the morning hours so the plants have time to dry during the day. A home made remedy made up from 1 teaspoon baking soda, 1/2 teaspoon oil in 1 quart of warm water mixed in a spray bottle will control the disease if applied on a regular basis. Sulfur is also used to control powdery mildew.

Black Spot

A fungal disease common to roses can be controlled by mulching under the plants to prevent water from splashing. The fungus spores that fall to ground are carried in the splash-back and the plant is re-infected. Keep your roses very clean, remove and destroy diseased foliage or fallen debris from under the plants. Avoid wetting the leaves if possible. Weekly applications of sulfur may help to control fungus diseases.

Canker

A fungal disease that causes die back on roses. Remove and destroy the injured canes for best control. This disease is spread by splashing rainwater, splash-back, insects or dirty tools. Canker spores can enter plants through pruning wounds. Don’t stimulate new growth with fertilizer or pruning when you suspect canker. New growth is most susceptible. Keep the area around the plant clean and raked up. Pick or prune infected parts as soon as they occur. Copper compounds may have some effect.

Leaf Drop

Rose leaf drop can be caused by a number of reasons; lack of water, disease or insects feeding on roots, excess water if the plant is growing in a container, slow draining soil or inadequate light. If you suspect any of these conditions, remedy the situation. For example, water more deeply, open the drainage hole in the container to improve drainage or treat for insect pests.

There are several diseases which cause leaf drop including black spot, apple scab and cherry leaf spot, all fungus diseases. Fungal disease can be treated by raking up the fallen leaves to prevent further spread and using micronized sulfur as a weekly spray treatment.

Yellow Leaves

There are several reasons why roses may develop yellow leaves.

One reason is spider mite, a sucking insect pest; check the undersides of the leaves for minute webbing or dust size specks.

Another more serious reason roses might develop yellow leaves is a viral disease infection; if you suspect viral infections, remove and destroy the plants.

Yellow leaves may also be caused by scale insects which look like small bumps on the bark, but they will suck the life from many types of plants, not just roses.

Or, the plant may simply need to be fertilized. Control the insect problems with insecticidal soap mixed with pyrethrin, and if you find scale insects, add a small amount of horticultural oil to the spray mix.

Note: All plants shed leaves during the growing season. A small amount of leaf drop is natural.

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