SPRING & EARLY
SUMMER ROSE GARDEN CARE (May-June)
by
Albert Ford, Editor, MRS Newsletter
Quick Links:| Fertilizing | Spraying | Mulching | Pruning | Preparing Cuttings | Watering | Weed Control |
Your first fertilizing was probably done around
April 15th and involved a general purpose fertilizer of Nitrogen(N), Phosphorus(P)
and Potash(K). Some gardeners use 10-10-10 for this purpose. Some supplement
with a product that will give additional nutrients like alfalfa pellets
or meal, cottonseed meal, urea, fish emulsion etc. They also add two tablespoons
of magnesium sulfate (Epson Salts) to encourage basal breaks, (new canes
from the crown) and to produce healthy green leaves.
In Maryland, the next general fertilizing
should be planned for about June 15th. This application should be done
with a general fertilizer formulated for roses. They usually contain the
three basic elements (N-P-K) and some minor elements. There are a number
on the market and your garden center is the place to look. Useful for
this purpose would be such fertilizers as Electra, Lebanon Rose Food,
Espoma Rose-Tone, Ortho Rose Food, Carl Pool Instant Rose Food or a Peters'
fertilizer. The latter comes in a variety of formulations and Peters also
packages trace elements separately. These products are granulated and
should be applied in a circle around the plant about six to eight inches
from the crown and in accordance with the product instructions. The granules
should be scratched lightly into the soil and watered in. Since the root
system of rose plants includes roots near the surface, care should be
taken not to disturb them.
For your general information, in
addition to the three primary elements (N-P-K) required for good plant
growth and flower production, there are three secondary elements and a
number of trace elements necessary. The secondary elements are Calcium,
Magnesium and Sulfur, and the trace elements include Boron, Chlorine,
Copper, Iron, Manganese, Molybdenum and Zinc. Each plays its part in good
rose culture. The most convenient method of applying trace elements is
to select a fertilizer containing them or to apply a product like Peters
in conjunction with the June and August feeding.
Many rosarians are now using liquid plant
food in between major feeding (April, June & August) and especially
before exhibitions. Liquid plant food can be applied as a spray and can
be combined with sprays for fungus and insects. They are systemic, meaning
that they are available to the plant's foliage without action of the root
system. Absorption is through the cuticle or skin of the leaf and the
stomata (the vents in the leaf surface that govern the rate of transpiration).
Experiments with radioactive nutrient ions have shown that most absorption
takes place through the lower leaf surface. This is thought to be so because
of the thinner cuticle and usually rougher surface. There is some evidence
that foliar feeding in conjunction with the application of a fungicide
increases the effectiveness of the fungicide in controlling blackspot
and powdery mildew (The Rose, 1984).
It is generally recognized that leaching
of nutrients occurs from the soil in periods of continuous heavy rain;
leaching of fungicides and nutrients also occur from the leaves under
the same conditions. It is advisable, therefore, to re-spray as soon as
the weather clears. One additional point is that foliar feeding should
not be used in hot weather because it increases the probability of leaf
burn. A plus to foliar feeding; however, is that it can be used later
in the season than top dressing of a fertilizer without inducing undesirable
late season soft growth.
Three foliar feeding products generally
available are Peters Professional 20-20-20, Ra-Pid-Gro 19-24-18 which
also contains Boron, Copper, Iron, Manganese and Zinc., and Stern's Miracle-Gro
for Roses 18-24-16 which contains also Copper, Iron, Manganese and Zinc.
These products are generally applied at a rate of one tablespoon per gallon
of water; however, you should check the instructions on the product you
choose.
Your spray program is probably already underway
and should be continued every seven to ten days throughout the growing
season.
In Maryland we usually must spray a fungicide
for blackspot and powdery mildew and an insecticide for a variety of sucking
and chewing insects. A point to keep in mind is that we use fungicides
as a preventive even though we cannot see evidence of blackspot, powdery
mildew, or rust; we spray an insecticide when we see evidence of insects
that we cannot control by other means.
You may have your favorite sprays already,
but if not, here are some suggestions.
FUNGICIDES:
One of the better fungicides is Ortho's Funginex Rose Disease Control. The main ingredient of Funginex is Triforine which can be purchased separately under the Ortho name. Although the cost of a quart of Triforine is more expensive than an equal amount of Funginex, it is less expensive in the long run. Funginex, for example, is applied at a rate of 1 tablespoon (1/2 fl. oz.) to a gallon of water; Triforine, at approximately 1 fl. oz. to six to eight gallons of water depending on strength required.
There are other fungicides one may wish to use. In fact it is generally regarded as a good idea to switch off to a second choice during the growing season because it is believed that the fungus responsible for blackspot can adjust--or become tolerant--to a given fungicide as do fungi that attack other crops. This point, to my knowledge, has not been tested experimentally with roses; however, a good many rosarians follow the principle.
For Blackspot, use one of the following:
Phaltan : 2 teaspoons/gal.
Benlate: 1/2 tablespoon/gal.
Daconil 2787 (Fungi-Guard): 2 Tbls/gal
Benomyl: 1/2 tablespoon/gal
Please note that Phaltan can burn plants in very hot weather. Daconil 2787 was discussed at length in the March, 1990, issue of The American Rose.
Although all of the fungicides mentioned above control powdery mildew reasonably well, Rubigan is a product formulated especially for mildew and provides excellent results. Special care is required in its use; however, and it is very expensive so it is desirable to get others to go in with you on a purchase. I usually have to purchase it out of state; however, The Meyer Seed Co. was able to provide it this year. Rubigan is applied at a rate of 2 table-spoons to 5 gallons of water.
INSECTICIDES:
For the general gardener who also grows roses a convenient product to use is Ortho's Orthenex, a material that combines Funginex (fungicide), Orthene (insecticide) and Vendex (miticide). Bear in mind that when Orthenex is used one is spraying for insects too. Some rosarians feel this does damage to the environment especially by eliminating useful insects and prefer, instead, to use an insecticide only when the in-sects in evidence cannot be controlled without it. If this is the case, Orthene, or Isotox, both Ortho products, available separately, can be combining with the fungicide, like Funginex.
Sometimes special treatment is required for infestations of insects or to control varieties which seem to thrive despite the use of our regular insecticide. If water does not control Spider Mites, for example, we may have to resort to Vendex, or a relatively new and highly effective miticide, Avid. A misting of buds and flowers with Mavrik Aquaflow will control cucumber beetles and thrips. Sevin is helpful with the control of Japanese Beetles, although the preferred treatment is to put down Milky Spore Disease which attacks the beetle larvae underground and eventually reduces the number of adults such that hand picking is all that is necessary to control them. Don't use traps for Japanese Beetles unless you are able to locate them a long distance from your roses or to place them in a neighbor's yard. Traps do attract beetles but sometimes to the wrong places.
Another bit of advice is that in spraying it is a good idea to use a "spreader-sticker" with your chemicals to produce thorough and even coverage of the foliage. Commercial products for the purpose are available; however, mild household detergents (1/2 teaspoon/gal) works as well. In this area many competent rosarians also add a tablespoon of white vinegar per gallon of liquid. This is done they report to neutralize the pH and to speed up the action of the chemicals.
A mulch is a material placed in your rose beds
or around your roses for a variety of reasons, not the least of which
is to provide a neat, manicured look to your garden. There are other equally
important reasons for mulching. Some measure of weed control is provided,
moisture is retained better, a more even soil temperature is maintained
in summer and winter, soil crusting and erosion is prevented and mulching
eliminates the need for constant cultivation. Mulching also encourages
root growth, activates earthworms and bacteria in the soil and, if the
mulch is organic, renews and rebuilds the humus content of the soil.
A variety of materials are available for
mulching including hardwood bark, pine needles, rotted manure, straw,
wood chips, mushroom compost, gravel, ground corn cobs, grass clippings,
straw, tree leaves, peat moss, black plastic, sawdust and nut hulls. The
kind of mulch recommended depends on the availability, cost, ease of handling,
and to a certain extent the action of the material on the soil. Peat moss,
for example, is expensive and must be kept moist for it tends to compact
and shed water. Straw has a tendency to reduce the nitrogen in the soil
but does furnish potassium. Black plastic is hard to manage and can become
unattractive as a consequence.
If you are thinking about mulching for
the first time this year or if you have decided to change the mulch you
have been using, inquire at a public garden or contact other members of
the rose society. For a number of years I have used hardwood bark which
is purchased in three cubic yards lots. It makes for an attractive garden,
minimizes weeding and adds nutrients to the soil as it decays. It does
have to be replenished regularly to maintain two to four inches in the
beds. Additionally, hardwood bark mulch affects the pH of the soil by
lowering it more to the acid side and as a consequence additional lime
is required to maintain a pH level of 6.5, slightly, but not excessively,
on the acid side.
On the point of pH, if you do not
have a meter or wish to check on the reliability of the one you have,
there is another simple and inexpensive way of doing it. Indicator strips
are available from Whatman LabSales which will give you a reading with
an accuracy of .2 to .3 pH units. The procedure consists of taking a sample
of soil 8-10 inches deep in the root area, mixing the soil sample with
water from your regular water supply and matching colors of the test strip
to a standard to ascertain the approximate pH. Test strips and instructions
can be ordered from Whatman LabSales, P.O. Box 1329, Hillsboro, OR 97124
or you can place your order by calling 1-800-942-8626. You should ask
for catalog No. 2628R990 (pH range 5.2 to 6.8).
A convenient way to apply hardwood bark
mulch is to mound one's plants with it as a winter protection to be removed
and spread out over the rest of the bed in the spring. This was done in
my garden in November of 1989, and as of pruning time this year, no plants
were lost, although admittedly, very hard pruning was required on some
of them.
Effective use of pebbles as a "mulch"
for some 700 roses in the garden of Dr. & Mrs. Joseph Kassab in Wallingford,
PA was reported on in the Nov-Dec, 1989, issue of the Newsletter.
In May one should check on the spring pruning to determine if there has been further die back and if so to remove such down to an outside bud or leaf growth. Similarly, some of the pruning decisions made in early spring may require correcting in May. There may be growth toward the center of the plant, for example, which can now be remedied by pruning at a somewhat lower level to an outside eye. Cane pith (center of cane) should be white or cream color, if it is tan or brown, the indication is that further dieback of the cane will occur and that the cane will die even though some green outer bark is supporting leaf growth. The stress of warmer weather will cause the dieback to continue down the entire cane.
Another good idea, according to Howard Walters, is to clean up the bud union by trimming off the old canes and stubs. A clean bud union exposed to the warmth of the sun will reward you with many more basal breaks, Howard reports, and eventually more bush and better roses. Paint each cut at the crown with the material you have selected for this purpose.
Of course, the first pruning as a result of spent blooms occurs during June in this area. This pruning, commonly referred to as "deadheading", should be done throughout the year to encourage further flowering. Normally we are not interested in the formation of hips at this time of year nor in encouraging dormancy. The method to use in deadheading Hybrid Teas is to remove the spent flower by cutting the it away from the plant at a point on the cane where five or seven leaflets are growing. The cut should be made 1/4 inch above the leaf axal of an outward growing bud and should slope downward toward the center of the plant.
Floribundas and Grandifloras are deadheaded much the same way, however removing the center bloom from Floribundas early produces a more uniform spray which is important for exhibiting. Some gardeners recommend removing spent blooms from Floribundas and Grandifloras as they complete their bloom cycle without disturbing the balance of the spray. Once all blooms have been removed these classes are pruned like a Hybrid Tea. Old Garden Roses also profit by deadheading, in that, recurrent bloom is encouraged in those varieties which are intermittent or repeat bloomers.
During the season you should be attentive also to unproductive growth which tends to crowd the middle of the plant and thus restricts sunlight and the flow of air. This growth should be removed along with any "blind shoots" which are twiggy stems of leaf clusters that do not terminate in a bloom bud. Care should always be taken not to disturb new growth from the crown or bud union of the plant which is most often a new basal break and thus the next cane to bear flowers. Basal breaks may also arise within five inches or so of the bud union. These shoots will grow very rapidly and are easily broken off by the wind. Protect them with a small stake and soft material like a piece of nylon hose. The loss of a basal break is an unhappy event for a rosarian. Further, on the point of basal breaks, some rosarians, including a commercial rose grower, Rayford Reddell, in his recent book, Growing Good Roses, recommends pruning basal breaks at a bud eye when the cane is twelve to fifteen inches tall to encourage a sturdy branched cane that will produce more and better blooms.
Plant growth from the understock rather than the crown should be removed whenever it is identified. To remove these, so called, "suckers" one need dig beneath the soil to the point where the sucker is growing and prune flush at the growing point. Paul Lord, former President of the MRS, was fond of saying, "tear the rascals out, or they will return." To prune suckers otherwise simply encourages their continued growth which can ultimately take over the entire plant. Suckers can be identified by the foliage which is usually smaller in leaf size and of a different shade of green than the foliage of the budded plant. Of course, you don't have to worry about suckers from miniatures since practically all of them--except tree roses--are propagated on their own roots as cuttings from the mother plant.
Often three buds appear on a cane, a center bud with two guard buds. Sometimes each will start growing. The grower, according to "Pop" Warner, should never let more than one bud produce a shoot at any given eye. The unwanted bud or buds are removed by "finger pruning" with a gloved thumb.
There are many ways of preparing cuttings and once you have developed a successful technique, stick with it. The easiest and most convenient method for me consists of cutting the fading bloom of the variety I wish to propagate at a point on the stem which will provide four bud eyes and placing the cutting immediately in water.
The cutting is prepared by removing the bloom and the leaves from the lower two sets of leaflets. The end of the cutting, to be placed in growing material, is stripped on several places of bark and the stripped areas and end are coated with Rootone. The prepared cutting is then placed in a pot filled with a growing medium consisting of equal parts of soil, sand and peat moss. A pre-punched hole in the damp medium is used for the stem, and the medium is tamped firmly around the stem.
The variety of rose and date is recorded on a marker placed in the pot and the cutting is enclosed in a plastic bag supported by two bent pieces of inverted U-shaped wire. The plastic bag is air tight except for a small hole at the top which seems to prevent the cutting from damping off. The bag acts like a small greenhouse. The prepared cutting is then placed in a shady place to mature. Shortly after new leaves appear, the plastic bag is removed and the cutting is given a water soluble fertilizer such as Ra-Pid-Gro. Gradually the cutting is moved into full sun after which it can be planted in the garden where desired. The planting should follow the instruction for new container roses provided in the last issue of the MRS Newsletter.
Should this be the year you had planned to get started in hybridizing, in this area, June is the month. Crosses made after the end of June have a decreasing probability of producing mature seeds before the onset of cold weather. This subject can be treated in more depth should there be sufficient interest.
Some growers will advise that wet rose foliage is to be avoided and deliberately spraying roses with a sprinkler is foolhardy. Others will advise that roses enjoy and benefit from an occasional cleansing shower. A strong stream of water from a good water wand is certainly a good way to rid the roses of aphids or spider mites.
Following rain or overhead watering, it is a good idea to re-spray because blackspot, for example, requires moisture to infect our plants. In fact, the splashing of soil containing the spores of blackspot is the start of plant infestation if unattended to.
As mentioned under Mulching, a two to
four inch layer of mulch will do much to reduce the weeds in your rose
garden. However mulching does not eliminate weeds entirely. There are
a number of products designed to prevent the germination of seeds that
would otherwise result in weeds. One of these is Preen which can be used
in rose beds. The granules are used at the time of the first fertilizing
and are scratched into the soil around the plants. It is best to remove
the mulch if it has already been applied and to scratch Preen directly
into the soil. This product does a reasonably good job in spring and early
summer; however, the material does not last throughout the year. In my
experience, late weeds appeared as usual in my beds and hand weeding had
to be resorted to. Another product which I intend to try this year on
a limited basis is Scotts'Flower and Garden Weed Preventer.
Without question the best product to kill
weeds in brick walks and in other stone or gravel walkways which are reasonably
remote from plants is Roundup. This product is systemic and gradually
kills the weed, root and all. Some growers use it in their rose beds,
taking special care that the droplets do not touch the foliage or crown
of the plant. It was used effectively last year at the Heritage Rose Garden
at Cylburn within inches of the rose plants without any harmful effects
to the roses.
updated April 30, 2003