Gardening Note #10
Roses
Roses require very high maintenance but will grow well in
Cumberland County if: 1) planted properly in well-drained
soil, away from
tree roots, and 2) a regular spray program is followed. They
generally bloom from early May until late fall.
How to buy:
Buy from reputable nurseries only. Bargain roses are very
often plants that are not named correctly and have been discarded
by greenhouse growers. They usually have an understock that is
suitable for greenhouse growing but is unsatisfactory for garden
use.
Types:
- Hybrid Tea: Buy #1 grade, 2-year, field-grown
plants, with 3 or more stems 18" or
longer, branching no more than 3" above the bud union.
- Floribunda or Grandiflora: same requirements
as above but 15" stems.
- Climber: same requirements as above but 24"
stems.
- Old Roses: defined as roses in commerce prior
to 1870; generally have fewer pests and diseases; bloom once
per year, and tend to get quite large.
- Miniature roses: Presently quite popular, they
are fairly disease free and, since they are not grafted, perhaps
sturdier.
- Tree roses: expensive; some find them hardy,
others disagree.
Cultural Needs:
- Sun: need at least 6 hours per day of sun;
morning sun is particularly valuable as foliage dries
sooner, preventing mildew and our most damaging disease, black
spot.
- Water: At least 1 to 1-1/4" per week. Water
at
soil line; wetting foliage encourages black
spot fungal disease as well as powdery mildew.
- Mulch: 2-3" of pine straw or pine bark mulch,
replaced each spring, discourages weeds and
helps retain moisture.
- Soil: Roses do well in our clay soils since
they are rich in minerals and retain moisture BUT
only if the soil is amended with compost or other
organic material so that soil is loose and well aerated.
If manure or compost is not available,a commercial manure product
such as Black Cow or a similar
product may be used along with pine bark mulch, mixed
well into the soil.
Planting:
- Plant in late February or very early March. Fall
planting is not recommended.
- As soon as plants arrive they should be soaked in water,
overnight if possible, and then planted immediately.
- Prune broken roots and prune tips of remaining roots to
force growth on feeder roots.
- Beds or individual holes should be dug a minimum of
18-24" deep, and plants spaced 3'
apart for adequate light and air circulation to
discourage diseases.
- Spread a 6" layer of organic matter (compost, Black Cow,
pine bark mulch, etc.) over
the soil, add 1/2 to 1 cup of dolomitic lime plus 1 cup
of bonemeal or superphosphate per plant, and mix well into the
prepared soil. Do not put any other fertilizer in the planting
hole. Build a cone in the center of the hole. When the
plant is set on top of the cone, the bud
union should be just slightly above ground level.
Carefully spread the roots around the cone.
Fill the hole 3/4 full with soil, packing it closely
around the roots to eliminate air pockets.
Tamp down evenly and fill the hole with water. After
the water has drained, use the rest of the soil
to build a 6-8" mound around the base of the plant. As
the weather warms up, reduce the
mound gradually.
Fertilization
Established Plants:
- When they show 1" of growth, in late March or early
April.
- Late May.
- End of July or early August. Do not fertilize after August
10th.
New Plants: Do not fertilize in spring until buds
are forming.
Type and amount: Use 1/2 cup per plant of 8-8-8 or
10-10-10, put in a circle about 6"
from the stem; scratch the soil lightly and water it in
well.
Insect and Disease Control Spray Program:
- Begin spray program about April when leaves are almost
fully out (start sooner in an
early spring). Continue spraying at 7-10 day intervals
through the end of October. Be sure
to spray both sides of the leaves. Do not spray
when the temperature is above 85 degrees.
- Formula:
| | 1 gallon of water |
| | 4 teaspoons
Captan |
| | 1/2 tablespoon
benomyl (Benlate) |
| | 1 tablespoon
acephate (Orthene)* |
| | 10 drops
Spreader Sticker (helps spray adhere to leaves) |
| * 4 teaspoons of liquid Sevin may be substituted for
acephate but ONLY
during prevalence of Japanese
beetles |
- In January or early February, after plants were cut
back in December and have gone into
dormancy, apply a dormant spray: Use liquid lime
sulphur according to label directions,
covering the bed AND bushes thoroughly. If red spider
mites, black spot or mildew have been
serious problems during the previous year, this dormant
spray may be repeated after 2 weeks. Do not use this spray
after sprouts have formed.
- Sanitation is an important part of disease control. Rake up
and destroy any diseased leaves that have fallen to the
ground, since they contain the innoculum for next year's disease.
In early spring, remove old mulch and replace with fresh mulch.
Pruning:
- Cut back to 2-3' in late December to prevent the wind
from rocking plants out of the ground.
- Prune again in February to the height of your knee,
18-24", cutting 1/4" above an outside
eye. Some growers use shellac on tips of all
canes as large as a pencil to seal out stem borers.
Always cut out dead or diseased canes to sound
wood, and remove twiggy, unthrifty growth.
- Climbers: Prune after first bloom in spring. If
any suckers rise from below graft union, cut
them off immediately. If newly planted, do not prune long
canes for first two years.
- Ramblers: Bloom in spring on last year's growth.
After bloom, remove at their base any canes that flowered and
select 3 or more young canes to take their place.
Cutting: When roses begin to bloom, cut short stems,
leaving 2-5 leaflet sets on stem. As the
season progresses, longer stems may be cut.
This information compiled by Cumberland County
Master
Gardeners.
This page was created on 4/20/98 using the Durham Master Gardener
Homepage as a model. Our thanks to them and especially to
Pauline Marx, Pam Reading and Eileen Lowenbach.
Revised on 05/07/98.