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March
24, 2005
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: There are little,
black bugs flying around my jade plant. What can I do to get rid of them?
In addition, I was rather grossed out by all the worms, bugs and molds
that I read about on your jade plant Web site. Are these common problems?
Is there anything I can do to reduce the chance of getting these pests?
(e-mail reference)
A: The black bugs
could be fungus gnats or fruit flies, depending on where the plant is
located. They are knocked down easily with a pyrethrin-based spray,
preferably from an aerosol can so they can be killed while in flight.
The material has a very low mammalian toxicity (extracted from the mum
family) and is not harmful to the plant, as long as you don’t
spray it directly on the plant. The insecticide is under pressure, so
it comes out cold. If concentrated on the foliage, it could cause tissue
burns. Fungus gnats originate from potting soil mixes. They more frequently
are found in highly organic potting mixes because, in part, that component
of the mix does not go through a sterilization or pasteurization process
like the inorganic part of the mix. You can repot with a quality potting
soil. The label should indicate that the contents are sterilized or
pasteurized. Fruit flies are common at this time of year, especially
around garbage disposals in the kitchen. It’s not a reflection
on your housekeeping, just an unpleasant fact. The best treatment is
to fill the sink up with hot, soapy water and run it through the disposal
while it is running. Jades are very popular because of their beauty.
In general, Americans care too much, emotionally speaking, for their
houseplants and spend too much time watering, fertilizing, etc. Amazing
as it may sound coming from someone well steeped in the horticultural
sciences, most houseplants that look their best are ones that are benignly
overlooked by their owners. I am not advocating this practice, but I
do encourage people to attempt to follow what is right for a particular
plant. Don’t give up in frustration if you have friends, neighbors
or relatives who “do nothing special,” but their plant is
doing everything you want yours to do!
Q: I planted several
arborvitae trees in 2003 that are doing fine. I now want to replant some
of them to make more room for a pit greenhouse. I’ll be using 4
feet of banked soil. Can I plant these trees up to the banked soil and
trim the south side of the trunks as they grow? My concern is that the
tree will suffer if it is up against the banked soil. My plan is to have
an underground path from my basement to the greenhouse with about 2 feet
or more of soil on top. How big is an arborvitae root system? How deep
do they grow? How close can I plant these trees to my underground path
or pit greenhouse? (e-mail reference)
A: “Up against”
anything, such as a wall of soil, wood, brick, etc., can cause problems.
Like any other plant, arborvitae need and better thrive when given breathing
room. I don’t know the architecture of your dirt wall. If the
wall is a straight vertical, it will cause problems. If the dirt wall
is sloped sufficiently, it may not cause any problems. In fact, you
could plant the small trees into the lower part of the bank.
Q: I thought I’d
ask another question because you did so well answering my last question.
I have a young aspen that is giving me trouble. There are three trunks
in very close proximity (all one tree?). Oddly, one has very yellow-green
leaves while the other two have dark green leaves. I assumed that this
was due to chlorosis and added some liquid iron (planning to get the soil
tested this spring before doing any further amending). Later in the year,
the tree appeared to exhibit signs of shoot blight. I’m guessing
that the decreased vigor of the plant and our cool, wet summer had something
to do with it. It may have been infected last year, but I didn’t
notice because we bought the house in June. Could you offer any suggestions
as to an appropriate course of action? (e-mail reference)
A: Take out the
problem tree trunk. If you don’t, it only will go downhill from
here. The root system is damaged or diseased and will not improve. I
speak from experience in attempting to correct maladies as you describe.
I have tried iron injections, aeration, vertical mulching, etc., but
to no avail.
Q: What is air-layering?
I have a tall, skinny schefflera. You’ve talked about air-layering
when you cut it back. In addition, can you root the plant cuttings in
water? (e-mail reference)
A: That’s
a good question. The answer is in the “Home Propagation Techniques”
bulletin. The bulletin is available on the Web at www.ext.nodak.edu/extpubs/plantsci/landscap/h1257w.htm.
You can root cuttings in water, but difficulties often come up when
transplanting the cuttings into a potting soil mixture. You are better
off rooting them in a media, such as sand/peat, and then moving the
root mass and media into the container you will be keeping it in.
Q: We have two arborvitae
next to our front door. They are about 8 feet high and look very out of
place because of their height and location. Is it possible to cut them
down significantly? (e-mail reference)
A: It is done all
the time! If done properly, no one will ever know that the plants were
a lot taller.
Q: I’ve had
a spider plant for more than two years. I think it is a variation on the
standard spider plant because it has more curly leaves. When I bought
it, I probably had 20 babies shooting out of it. I keep it in the kitchen
window where it gets light most of the day. I do not think I am
overwatering, but recently all the babies died. Within the last month,
all the stems to the babies turned brown and some babies fell off. I would
like to revive the plant and get the spiderettes growing back. I have
other spider plants that have not produced babies in years. What specifically
causes spiderettes to grow? (e-mail reference)
A: Spider plants
best thrive in a pot-bound situation and have access to sunlight. A
spider plant should be in a room where the sun shines through the window
at some point in the day. It doesn’t matter if it is direct or
indirect sunlight, as long as the sun coming in can brighten the room.
The production of spiderettes is tied, somewhat, to day length. In response
to increasing daylight, the plant should begin producing flowers and
spiderettes sometime this spring. Don’t overwater or overfertilize
this plant species. Both are needed, but not in any abundance. That
may or may not have caused the demise of the spiderettes on your plant.
Q: I received a zebra
plant for Christmas. I would like to know how to take care of it. I’ve
heard it is a difficult houseplant to grow, but mine seems to be doing
well. (e-mail reference)
A: By zebra plant,
I assume you mean calathea zebrina. They do not do well in direct sunlight,
so it should be shaded continuously. Watering should be watched closely
because the potting soil should not dry out. This group of plants is
particular about humidity. Surround the plant with damp sphagnum peat
on a tray of pebbles filled with water. That will help a lot. You also
could purchase a humidifier for the room. The room temperature should
not be allowed to go below 60 degrees. Fertilize only when the plant
is showing active growth. Calathea zebrina make good terrarium or bottle
plants.
Q: When is my kalanchoe
supposed to bloom? It bloomed all summer in my greenhouse, but I would
like to see it bloom for Easter. I read that the plant should be covered
for about a month. I did that, but it budded within a week. How long should
I leave it covered? (Onaka, S.D.)
A: These are short-day
plants, which means they should be getting 12 1/2 hours of total darkness
a day. All I can tell you is to go ahead and cover it. When you see
buds forming, no further cover is necessary. Plant vigor, temperature
and the growth stage the plant is in also are factors, but the main
triggering mechanism is the lack of light exposure.
Q: I bought a jade
plant approximately three years ago. It has proved to be a rather hardy
plant. I keep it outside during the summer and bring it inside during
the winter. Twice I have forgotten to bring it in before the first frost
hit. Surprisingly, it recovered quite well each time. It has spawned a
few smaller plants in the pot. I decided to take one of these smaller
plants and put it into a large terrarium with my pet lizard. The lizard
eats insects, which are mostly superworms and crickets. After placing
the plant in the terrarium, I realized these insects probably are going
to eat the plant. Is that the case? (e-mail reference)
A: Unless you have
the terrarium swarming with insects, the plant should be safe. I assume
you have other plants in the terrarium as well. For the most part, the
insects you place in there for lizard consumption are disoriented and
“out of season,” so they are not in a foraging mood. However,
isn’t this what you want to create, a miniature ecosystem only
with the fittest surviving? Even if the plant should become an object
of desire for the enclosed insects, any plant worth its salt should
be able to survive an occasional nibble now and then.
Q: My son threw a
sandal at my Yucca cane plant and broke the stem about a quarter inch
from the dirt. What can I do to save the plant? It truly is a beautiful
plant. (e-mail reference)
A: Make a clean
cut to remove the top of the plant and stick the cutting in a rooting
medium. The base also eventually should send up new shoots. In theory,
you should get two plants out of this little accident! Go to my Web
site at www.ext.nodak.edu/extpubs/plantsci/landscap/h1257w.htm
to learn more about home propagation techniques.
Q: I have a large
section of lily of the valley that I planted 12 to 15 years ago. The plants
are healthy and spreading. Last year, they turned brown and looked dead.
Any idea why? Also, I have hosta of all sorts growing around my yard.
I’ve had quite a problem with tiny holes in the plants. I was told
slugs caused the holes. By the time the lilies were withering last year,
the plants were full of holes and looked extremely frail and lifeless.
(e-mail reference)
A: I have no idea
why your lily of the valley turned brown. Overwatering is a possibility.
Your guess is as good as mine is. You may want to contact your local
Extension agent to find out if a horticulturist or plant pathologist
is on staff who can diagnosis the problem. Slugs and hosta go together
like peanut butter and jelly. Remove the foliage before new growth begins
this fall. At the same time, place several dishes or traps of slug bait
that is available at most garden centers. This should at least partially
control them. As best you can, avoid any excess moisture on the plants.
Also, try to remove all slug hiding places, such as boards, rocks, rotting
foliage, etc.
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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