Hellebores
Q. From what I have read,
hellebores are supposed to spread. I have a few
I planted four years ago, and they seem to be
the same as when I planted them. They are planted
in a bed of vinca. Should I remove more vinca
that surrounds them? I do fertilize them and protect
them with a winter mulch. What else should I be
doing to have more plants?
A. Hellebores increase slowly into clumps
so have patience, counsels Chris Darbo, wholesale
manager of The Natural Garden, St. Charles, and
an enthusiastic hellebore grower. "I have
Helleborus foetidus, which has finely cut leaves
and blooms in January, and H. orientalis, the
Lenten rose. Both have increased in twelve years
to four times the size of the original plants,
but they haven"t self sown. They are planted in
a bed of sweet woodruff in a partly shady location."
"I also have a clump of H. orientalis that
was transplanted into my back yard five years
ago, and it seeds all over the place. It is planted
in shade with no ground cover. My theory is if
the seeds can"t reach the ground, they can"t grow!"
It takes three years before seedlings bloom.
According to Darbo, hellebores do not need fertilizer.
She never rakes leaves from garden beds but instead
lets fallen leaves act as a winter mulch. Leaf
decomposition over the years has helped her soil
to become more loamy.
H. niger, the Christmas rose, does not self seed
as readily as H. orientalis and H. foetidus.
Note: A new strain of H.orientalis has recently
reached the market. Known as the Royal Heritage
strain, it includes colors and patterns never
seen before in the species. Fifteen years in the
making, Royal Heritage hellebores were developed
by John Elsley, Director of Horticulture at Song
Sparrow Farm in Avalon, Wisconsin.
Variegated
Sedum
Q. I have a large
variegated sedum with pink flowers that I have
had for years. I noticed that it has started to
send up some all-green shoots. Why is it doing
this and how can I keep my plant variegated?
A. All variegated plants contain a combination
of green cells with chlorophyll and white tissue
with no chlorophyll, which produces the green
and white effect. Variegated plants are genetically
unstable, so sometimes the tissues revert to all-green
cells and send up solid green shoots from the
base of the plant. Because these shoots contain
more chlorophyll than the variegated tissue, they
are more vigorous. Thus they can quickly overrun
a plant, according to Hortech, a developer and
grower of sedums.
Cut the green shoots off at the base of the plant
as soon as you see them. It is possible you have
induced vigorous growth by giving the plant too
much high-nitrogen fertilizer, so it would be
wise not to fertilize. It sometimes helps to divide
your plant and then choose the most variegated
stems for a new plant. Since your sedum, a cultivar
of Sedum spectabile, is such a rapid grower, it
will quickly become a new clump after division.
Newer named cultivars are more genetically stable
and do not have this problem. Back
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Siberian
Iris
Q: My Siberian iris 'Gracilis' plants have only
one bloom per clump. I have five 3 to 5 year-old
clumps that are 8 to 10 inches wide. They do not
appear to be crowded. All are planted in a moist
area. Why is there only one bloom per clump?
A: "Iris bloom is directly proportional
to the amount of sun received," proclaimed
Chuck Simon, Hinsdale, past president of the Northern
Illinois Iris Society, who grows 10,000 rhizomes
of 1,000 to 1,500 iris varieties. Iris need 4
to 5 hours of sun, but full sun is best. Another
cause of bloom failure could be iris borers, which
eat mature fans and cause only minor increases
in plant growth. Spray with Cygon 2E in spring
when eggs of borers hatch in order to break their
life cycle. When transplanting iris, make sure
the roots remain moist. Grow them in moist but
not wet soil. In the first year after planting,
water them religiously. Once past that point,
they are very hardy. Simon, a master iris
judge, referred to the American Iris Society checklist
for any special cultural conditions affecting
bloom and discovered that this variety is very
old. Iris siberica 'Gracilis' was introduced in
1927. Back
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Russian
Sage
Q: Our Russian
sage (Perovskia) is full and bountiful but will
not stay upright. Is there anything we can do?
Is there a way to split some off when it has outgrown
its space? Should it be trimmed back in fall or
spring?
A: The normal growing habit of Russian sage
is to open in the center, according to Tina Pansic,
staff horticulturist at Chalet Nursery, Wilmette,
who says this is a common complaint. Russian
sage
must be grown in full sun and can be supported
by pea stakes (willow or dogwood branches) or
commercial wire stakes. A new cultivar, 'Little
Spire' is shorter and will stay upright. Your
plant can be divided by breaking up the root
system
with a spade as the bottom stems get woody.Wait
until spring to cut the plant to the ground. Plants
that are cut back in autumn suffer more winterkill.
Pansic cuts her perovskia halfway down in late
summer to control the spreading, and then cuts
it to the ground the
following spring. Back
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Purple
Coneflower
Q:
I have read that purple coneflowers (Echinacea)
are a good source of food for birds in the winter.
Will they be okay if not trimmed back until spring?
If so, how early should they be trimmed?
A: If your coneflowers remain standing over
winter, the seed heads will be available as bird
food and will also be an attractive presence in
the winter garden. They should be cut back in
early spring before April. If you prefer, you
can cut the plant back after frost and throw the
seed heads on the ground. Back
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Azalea
Q. We moved into a house with a lovely azalea that didn't bloom. We thought it might have been over-pruned. Last fall we did not prune it and now it still hasn't bloomed. I was hoping to transplant it this year, but it looks rather sickly. Shall we prune it again and give it another year? Can I still transplant it?
A. Stop pruning your plant since you may have over-pruned it. Evergreen azaleas only need tip pruning in July after their flowers have faded.
Concentrate now on rebuilding the azalea into a healthy plant. Do not transplant a sickly one. Feed your plant regularly with an liquid acidic fertilizer. Keep your plant weeded and its roots moist by using mulch because azaleas are surface rooters. Make sure your plant is situated in soil with good drainage and in a part sun/part shade location.
Try this regime over summer and evaluate your plant next spring, advises Charlene Wooten, manager, Cedar Hill Nursery, Lake Zurich. Back to top
Peonies
Q. I have some peonies that I want
to transplant but cannot plant them in their permanent place until next spring when our new house will
be built. Can I dig them now and transplant them again next spring?
A. The correct time for transplanting herbaceous peonies is late September into October. Cut back the foliage when you dig them up. Each clump you move should have at least three eyes, or growth buds, and thick tuberous roots. Dig a hole deep enough to cover the eyes with two inches of soil when you transplant. If planted too deeply, they will not bloom.
Transplant the peony into its
temporary place, or else move it into
a container and dig the container into a shady area, not in full sun. Be careful about watering the container plant; try to keep it evenly moist. Next spring, move the peony into its permanent location, suggests David Leider,
perennial grower at Klehm Plants, Barrington.
"Replanting in spring disrupts the roots and will halt blooming for one year. Peonies are pretty strong plants and very hardy. They will recover," says Charlotte Thayer, assistant to the owner at The Natural Garden, St. Charles. Back to top
Hydrangeas
Q. When is the best time to cut back hydrangeas? How far do I cut them back?
A. Pruning hydrangeas depends on the species. Oakleaf hydrangea (H. quercifolia) and Peegee hydrangea (H. paniculata), with its well-known cultivars 'Limelight' 'Little Lamb' and 'Tardiva', are woody shrubs that bloom on old wood. Trim them within two to three weeks after flowering. The following year's primary flower buds form near the top of the stems in late summer. If you wait too long to prune, you will be cutting off flowers on the old stems.
The new bigleaf hydrangea (H. macrophylla) 'Endless Summer' is an herbaceous plant that dies to the ground over winter and starts into new growth in spring. It can be cut at any time since it flowers on both old and new wood.
Hydrangea 'Annabelle' (H. arborescens) can be trimmed at any time. "It dies back totally to the ground each year so you can keep it trimmed to the size you want," says Jean Bragdon, garden center manager at Lurvey's Garden Center, Des Plaines. Back to top
