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March
31, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I have a large
poinsettia I’m hoping to keep alive, but I’m not sure how.
There aren’t many red leaves left on the plant, but the soil is
moist. Is there a way to keep it alive so it will bloom? (e-mail reference)
A: The lack of red
leaves should not be a concern. Continue to care for the plant the way
you have. If possible, keep it in a bright location. When the danger
of a frost is over, move it outdoors where it can grow like a shrub.
Take cuttings from the new growth this summer. Root and pot the cuttings.
Bring the new plants and the mother plant indoors before the first fall
frost and then subject them to short days (more than 12.5 hours of darkness)
to initiate leaf coloration. You can leave the plants uncovered after
coloration.
Q: I’m going
to try raising wave petunias in a hanging basket. I planted the seeds
Jan. 1 and then transplanted the plants into pots Feb. 19. I give them
12 hours of fluorescent light per day. I need to know how many hours of
light per day they need. Do I trim the plants? What is the best room temperature,
feeding practice and should I use bottom heat? I would like these to be
ready for Mother’s Day. (e-mail reference)
A: Increase the
lighting period to 14 to 16 hours. More light will make a big difference
on plant vigor. Fertilize with Miracle-Gro every other week using a
diluted solution. The room temperature should be in the mid-70s, if
possible. Petunias are tough and forgiving plants, so they should respond
well.
Q: In early October
2002, we hired a local nursery to plant five Norway spruce and five blue
spruce. We’ve had a tree service take care of the trees for the
past two. Last fall, the nursery expert advised us to water each tree
once a week for about 20 minutes until the ground froze. The tree expert
said we should water three times a week for 20 to 30 minutes until the
ground froze. We took the tree expert’s advice. We purchased a root-watering
wand and faithfully watered the trees. The blue spruce trees are doing
fairly well, but the Norway spruce are showing signs of stress. There
is some browning of the branches near the ground and some browning halfway
up. Both experts said we should not put up burlap to protect the trees
against wind damage. The brown areas are on all sides of the trees, but
mostly on the southwest side, the main direction of the wind. When can
we begin watering and how much should we give the trees? Should we use
the root-watering device? When and how do we fertilize? Since we’ve
been given differing opinions, I don’t know which expert to believe.
We have $12,000 invested in these trees. (e-mail reference)
A: Both spruce varieties
need water to become established, but they shouldn’t be watered
for 20 minutes each week for two years. Adjustments have to be made
for weather conditions and attention needs to be paid to each tree’s
response to the watering regime. At this point, examining the buds is
important. If they are plump and firm, you have nothing to worry about.
If they crumble and fall apart, there is a problem. I am surprised that
your tree service did not offer to spray the trees with Wilt-Pruf prior
to winter. That would have provided some protection against desiccation.
When the ground thaws, don’t be too quick to begin watering. As
the soil warms and dries, the roots will tend to follow the moving moisture
line to a depth determined by the air/water balance existing in the
soil. Applying water too soon will cause the roots to stay near the
surface, causing a saturated soil condition where the roots suffer from
anaerobic conditions. I would get the nursery personnel back out to
your place, since you have made such a sizeable investment, and ask
them to interpret the situation. They should provide expert advice because
they want you back as a customer.
Q: The zebra plant
I am trying to find out about is the “aphelandra squarrosa.”
(e-mail reference)
A: Aphelandra squarrosa
has about the same requirements as another zebra plant, the calathea.
Keep the potting soil constantly moist, but not soggy. Never allow it
to dry out. Provide plenty of bright, but indirect, light, keep it warm
(never below 60 degrees) and fertilize every other week. Keeping the
humidity high around the plant also is key. Mist the plant, set it on
a tray full of pebbles and water and use a humidifier. Any and possibly
all of these ideas may be needed to keep your zebra plant looking as
good as the day you acquired it.
Q: I was given a plant
a number of years ago. I was told it was a hoya. So far, it hasn’t
done very well. It is supposed to have a perfect white star blossom with
another star inside, which I haven’t seen. Is it a hoya and how
should I care for this plant? My uncle and aunt gave the plant to me,
but both now are deceased. (e-mail reference)
A: What you describe
sounds very much like a hoya, but I can’t say for sure. Assuming
it is a hoya, do not disturb the plant once the buds appear and don’t
remove the dead flowers. Don’t repot until necessary. Keep it
cool during the winter months (50 to 55 degrees). Give it bright light
throughout the year, with some direct sunlight. Water sparingly in winter,
but liberally during the summer months. Mist the leaves often, but not
when in bloom, and fertilize only during periods of active growth. Good
luck!
Q: I have microscopic
white bugs (they do not fly) that live in the soil of my plant. It was
outside last summer, but has been inside since it turned cold. The little
pests seem to surface when I water the plant. So far, I have tried spraying
it with a household pesticide and herbicidal soap. A friend recommended
that I water it with soapy water. I used regular dish soap without phosphates.
I filled the pot completely with the soapy water and then allowed the
water to drain. I waited an hour and then continued to flush out the rest
of the soapy water. I was told that the mites living the soil breathe
through their skin, so the soapy water would coat them and suffocate them.
I have done this twice and assumed it worked, but when I watered the plant
a week later, the mites had returned. Should I get rid of the soil? (e-mail
reference)
A: You have me stumped.
It could be a form of root aphid or root weevil. The bugs obviously
are impervious to your attempts to bring them under control. You didn’t
indicate if there was any apparent damage to your plant. Hibiscus tolerates
being handled and repotted quite well, so get rid of the soil. Use fresh
material that has been sterilized or pasteurized and is in an unbroken
bag. Be sure to wash the roots in tepid water and scour the container
or pot. Give the plant plenty of water. Avoid damaging the roots as
much as possible during the process.
Q: I am looking at
planting a row of evergreens for a windbreak and privacy hedge. The soil
is heavy clay and shale rock. I have seen an advertisement for a thuja
green giant, which I believe is an arborvitae. It’s said to be a
fast grower and adapts to all soil types. Have you had any experience
with this evergreen or would another variety, such as Canadian hemlock
or American arborvitae, work better in my soil conditions? (Dickinson,
N.D.)
A: I would encourage
you to contact Jerry Larson, former NDSU Extension Service agent, or
Craig Armstrong, Dickinson city forester. Craig has a lot of experience
dealing with plant materials in your area and would be in a better position
to give you advice. The green giant cultivar of the T. plicata may be
a worthy contender for your site, if you can propagate stock locally
(within zone 4). Keep in mind that this is the borderline for thuja
green giant hardiness, so you might be better off going with one of
the American arborvitae cultivars. This is where Craig or Jerry could
help you make a final decision better than I can.
Q: I have a hibiscus
at my office. It has been in a south window for two years and blooms every
week. It is getting leggy, but I’m afraid to mess with it because
it is doing so beautifully and it was a memorial at my father’s
funeral. What is the best way to trim it back without killing it? (e-mail
reference)
A: Don’t be
afraid to prune the plant back to the size you want. Make the cuts right
above a bud or lateral branch so you don’t leave ugly stubs.
Q: I recently became
the proud owner of two Christmas cacti. The one purchased from Homewood
Nursery in North Carolina (they participate in poinsettia cultivar trials)
is doing great. A section fell off during the trip home, but I have it
rooting in water. My future mother-in-law gave the other plant to me.
I was told that it is about 15 years old and from her grandmother’s
funeral (no pressure here!). This gift consisted of two long arms falling
to one side and brushing the floor. It is in a 6-inch pot, so it’s
not a pretty picture. I trimmed the arms back, leaving about five sections
on each of the two and started rooting the removed pieces. When is the
right time to repot the original? Can I pot the clippings with the original?
I also have considered potting the section that fell off the one purchased
from the nursery with the older one. (e-mail reference)
A: Just in case,
keep the two plants separate. Repot everything in the soil that you
want them to grow in. You have a unique opportunity to root all of these
cuttings into small, decorative pots and pass them out to your new family
after the wedding, if there is enough time. At your first opportunity,
pot the mother plant into the next nominally sized pot with the same
drainage characteristics as the original.
Q: Every spring, when
newer growth and buds begin, my rose plant gets a large infestation of
aphids. What is the best treatment and is there a way to keep them from
coming back? (e-mail reference)
A: Aphids love fresh
growing roses! They always have and always will. About all you can do
is spray the aphids with an insecticidal soap when they appear. If I
knew a way to keep them from coming back, I would be “one rich
Smith.”
Q: We seem to lose
our zucchini every year to vine borers. Is there a simple and effective
way to prevent this? (e-mail reference)
A: You can rotate
the planting site or do pre-emptive spraying. If this doesn’t
work, stop growing zucchini for two to three years. Hopefully, you have
neighbors who would be happy to share their bounty with you during that
time.
Q: This winter, we
attracted some very beautiful woodpeckers to our birdfeeders. Unfortunately,
one of the larger woodpeckers has dug a couple of large holes in the center
branch of my crabapple tree. Is there a product that I can use to seal
the branch? When is the best time to apply it, winter or spring? (e-mail
reference)
A: I would suggest
using Tanglefoot, which is a sticky material that comes in a can or
a large toothpaste-type tube. Smear it around the area of the woodpecker’s
activity because they hate to get their feet sticky, so they will move
to another tree or territory. As for the hole the woodpecker has made,
there isn’t much that can be done except to allow it to heal naturally.
There is nothing you can do except to cut back any jagged bark to help
facilitate healing.
Do you have a gardening
or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension
Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu.
Note to e-mail correspondents: please identify your location (city and
state) for most accurate recommendations.
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Source: Ron
Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu
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