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May
25, 2006
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: We are trying to
decide if we should plant a thuja green giant or an arborvitae (can't
decide on American or emerald). We're looking for a privacy screen from
our neighbors. We have a fair amount of mild winds that tend to blow through.
We have clay soil for the most part, but with some sogginess after heavy
rains due to runoff. (e-mail reference)
A: Both of your
choices are of the arborvitae species. Thuja plicata (green giant) is
a cultivar of the giant western arborvitae. It grows quickly and has
a broad spread. During the winter, the green color becomes a bronze.
It regreens with the advent of warm, spring/summer weather. The green
giant grows to a height of 30 to 40 feet and half as wide. What is being
sold to you as an American arborvitae is probably the dark green American,
also known as nigra. It supposedly will retain good color through the
winter months, get 20 to 30 feet tall and 5 to 10 feet in width, and
have a nice pyramidal form. The emerald arborvitae originated in Denmark.
It grows to about 15 feet, with a 4-foot spread. It stays green all
winter, tolerates cold in winter and heat through the dog days of July
and August. Your choice depends on what you are trying to achieve, other
than as a screen between properties. In my opinion, the nigra (dark
green American) would be the best fit, but only you can make that determination.
Q: Do you have any
ideas about curing what appears to be a fungus in my peonies? The peonies
are at least 30 years old and have a pretty bloom. During the summer,
they get brown instead of keeping their healthy, green foliage. Is there
anything I can do? (e-mail reference)
A: If you never
have divided them, it would be a good idea to do so at the end of this
summer. Your problem sounds like downy mildew symptoms. Try spraying
early in the season with mancozeb because it has good preventative qualities.
Q: I know someone
who has problems with spruce trees. The trees have pine needle scale,
winter damage and drought stress. However, the trees that appeared to
be dead are budding new needles, so I am wondering if the problem is needle
cast. Is there any hope for these trees? The owners have been watering
the heck out of the trees because they don't want to lose them. Does the
needle scale pose a threat to tree health? Is there a spray to prevent
it? Any feedback would be greatly appreciated. (e-mail reference)
A: These trees are
under a lot of stress and probably will not make it. I would love to
be wrong, but when a combination of factors that you describe come together,
usually it spells doom. Horticultural oil will help control scale and
watering can help offset drought. They probably don't know it, but their
spruce trees very likely have spider mite infestations, which periodic
hard sprays with water will help control. As for what sounds like needle
cast, spraying with Bravo (chlorothalonil) now and again in early July
might do the trick at arresting the progression of this disease. It
needs to be done at least two years in a row to be effective. I wish
them luck in their efforts. Sorry to be such a pessimist!
Q: They had to dig
up a large patch of lawn this winter here at the courthouse. Now they
are replacing the dirt with some weed-filled topsoil and would like to
plant grass. Since the dirt is from a less-than-reputable source, is there
some weed killer that can be applied or raked into the soil before planting
the grass seed? Can we plant grass seed from one of those little push
carts used for fertilizer? Can you plant the grass seed mixed with a starter
fertilizer or will it burn the seed? When is the optimal date to plant
grass in North Dakota? Any other tips you have to offer would be great.
I have used the two publications on planting grass that are available,
but they don't answer these questions. (e-mail reference)
A: Allow everything
to germinate that is in the low-quality soil. Hit it with Roundup after
that because it doesn't leave a toxic residue in the soil that would
impact the grass seed. Yes, the grass seed can be planted using a drop
spreader. However, it is not a good idea to mix fertilizer and grass
seed in a combined application because the rates of application differ
dramatically. Grass is seeded at 2 to 3 pounds per 1,000 square feet.
Fertilizer application rates vary depending on the formula, but usually
is applied at 4 to 5 pounds per 1,000 square feet. Optimal planting
time for lawn seed in North Dakota is mid-August to mid-September, although
it is planted anytime the soil is ready and the homeowner or client
wants it.
Q: I received a calla
lily during Easter. How do I take care of it? Does it last all year? Does
it have a rest period? How much water and fertilizer should I use? (e-mail
reference)
A: I'll do better
than just give you an answer. I'll provide a Web site, www.ext.nodak.edu/extnews/hortiscope/flowers/lily.htm,
for you to go to that will answer your questions on the care of this
plant.
Q: A friend of mine
has an apple tree that is 8 to 9 inches in diameter. It has been pruned
regularly and it produces tons of blossoms, but no fruit. Can you give
me any suggestions? (e-mail reference)
A: Plant another
apple tree nearby that is a different species. It could be there are
late-spring frosts that are killing the blossoms at their most vulnerable
point, no pollinating insects active at flowering time or it is too
windy and rainy at that time. These are the basic reasons for a tree
to not bear fruit, even though the tree is healthy.
Q: I was reading the
advice you gave on your Web site about goldfish plants, but I still have
a question. I’ve had a goldfish plant for almost a year. This spring,
nearly half of its leaves fell off and the plant appears sickly. The strange
part is that the leaves that are falling off are still green. Is there
anything I can do to save it? (e-mail reference)
A: It is going into
a rest period. Let it do so. Keep the soil barely moist for about six
weeks, then increase the watering and it should releaf for you.
Q: I want to do a
bed with rose bushes by a wall. In front of the roses, I want to plant
irises, daylilies and tulips. In the very front, I would like something
small, such as pansies. What would happen if I planted the bulbs in circular
patterns or something similar? Would some of the plants be hidden? Do
the plants have to be certain distance apart? I just don't want straight
lines of flowers. (e-mail reference)
A: Lay out a bed
shape with a garden hose, kicking the hose in and out to create a free-flowing
curve or curves. Then plant as you described, with the exception of
the daylilies being in front of the roses because their foliage may
get big, depending on the cultivar. You don’t want covered or
partially hidden rose plants because they need as much direct sunlight
as possible.
Q: I just (late April)
bought some tulips that are beginning to open their buds. Is it too late
to plant them in the yard and what is the best way to do so that they
will come up again next spring? I know nothing about planting tulips,
but think they are beautiful. Where is the best place to plant them? What
should I do once they finish flowering? If it is too late to put them
in the ground, what should I do with them until I am able to plant them?
Thanks for your help! (e-mail reference)
A: Plant the tulips
as they are in the pot and plant them in a sunny location. If you try
to separate tulips out of the pot, they will wilt and die. After the
foliage fades in June, dig up the potted bulbs, pull off the spent foliage
and store the bulbs in a cool, dry location until mid-September. After
that, plant them outdoors where you want. They do well in full sun or
partial shade.
Q: I have some hosta
plants in a backyard garden that the deer think are delicious! I would
like to try blood meal to treat them, but I’m not sure how strong
a treatment I should use. The bag suggests not overtreating the plants.
What strength would you recommend? How about adding dryer sheets and Dial
soap? Would that be overkill? (e-mail reference)
A: Forget the blood
meal because the deer will only laugh at your attempt! Up to a point,
three products have been shown to be effective in deterring deer activity,
which is about all one can ask for. The products are Plantskydd, Hinder
and Liquid Fence.
Q: I bought a house
with a raspberry patch on the south side of the garage. According to your
article, just about everything is wrong with the patch. The patch has
very tall canes leaning on the garage wall. The first year, I cut the
canes down to about 6 inches, but now they’ve grown very tall again.
I see that I should have cut them down to about 4 feet in early spring.
It probably is too late to do that now. The real reason I am writing is
that small sprigs are springing up all over my lawn in the vicinity of
the raspberry plants. Is there anything I can do about this? Any further
advice on the care of these plants would be appreciated. (Kindred, N.D.)
A: You can cut
the sprigs out with a spade or spot spray them with Roundup. Try to
avoid overspray or drift. The best approach is to dig a trench around
the raspberry patch, assuming you want to keep them for their fruit
production, and place a root barrier (BioBarrier) around them to keep
them in check. From my experience, you need to go down 8 inches or more.
Q: I have several
potted impatiens. They were growing great in large pots and cascading
over the sides. Lately, they have been getting leggy. The branches are
growing straight up, with flowers at the top only. I also have a problem
with a pink double impatien. The base of the stems appears to be rotting.
The plants are kept in moderate shade, good dirt and not overwatered.
What am I doing wrong? (e-mail reference)
A: Impatiens can
be cut back to force them to bush out. The plant that is rotting at
the base most likely has a soil-borne pathogen. It isn't anything you
are necessarily doing wrong. It just happens sometimes. Consider using
a soil drench fungicide, such as Funginex, in the future before replanting.
Q: I live a little
north of West Fargo. The Sheyenne River runs at the foot of a little cliff
in the backyard. Occasionally (including this year) the water will come
up over the cliff to a depth of about 12 inches and flood the backyard
for a few days and then subside. I have ordered two Manchurian apricot
trees to plant. Can I plant them by the edge of the cliff or would a few
days worth of flooding kill them? Also, do you have any tips on how to
grow apricot trees? Do they need full or partial sunlight? (e-mail reference)
A: You would be
accused of plant homicide if you placed them where they would get flooded,
even for a few days. Apricots have a hard enough time making it in our
environment without the root zone being covered in water or saturated
soil. Apricot trees need full sunlight and very little, if any, fertilizer.
Q: What do you think
of growing vegetables in a bale of hay? Here's a
Web site http://forums.gardenweb.com/forums/load/tomato/msg0308333916091.html?3.
(e-mail reference)
A: Gardeners are
crazy people and will jump at every novelty! It will work, but why do
it? The hay will attract rodents, at least for the winter. Who wants
to run around looking for hay or straw bales? The opportunity for disease
and insect problems being transferred from the bale to the living plants
is high. If garden space is not available, plant them in containers
with good drainage and use pasteurized soil. Why go to the expense of
using pasteurized soil in an unpasteurized bale of hay or straw? If
you have a farm, then the hay or straw bales are readily available,
but any farmer I know who wants to grow veggies will not resort to using
a bale. Thanks for the good question.
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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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