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May
6, 2004
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q:
There is a pine tree in my yard that is preventing grass from growing
underneath it. The pine boughs are cut off high so the ground gets plenty
of sun. I sprinkled on some lime and replanted because I figured the pine
needles were making the ground too acidic. Did I make the correct assumption?
(Moorhead, Minn.)
A: I am going to
give you a mild reprimand by saying, never assume anything about your
soil. It may or may not be acid in a pH reaction. Our clay soils in
this region normally have a pH of 7.5 or higher, so a little acidity
from the pine needles would make the nutrients more available for growth.
I would suggest using a shade mix that contains an ample amount of creeping
red fescue. If you are unsuccessful at growing grass, don't fight it.
Try growing flowers instead. It's done all the time.
Q: I am writing to
ask you about how to get rid of quackgrass. We had a new lawn put in a
few years ago and now the quackgrass is showing up in spots and spreading.
Weed killer labels usually list crabgrass but not quackgrass. Is there
any correlation between the two? (Garrison, N.D.)
A: I do not think
there is a correlation between the two except that both infect weak
and thin lawns. There isn’t a herbicide labeled for selective
quackgrass control for cool-season grasses, so hand-weeding is an option
in small areas. In larger areas with quackgrass spots, you may want
to spot-treat with RoundUp, following the label's directions. Re-seed
the dead spots with desired grasses. At times when the grass is not
under consistent stress, such as spring and fall, lower the mowing height
to about two inches. This will help prevent the quackgrass from spreading
too fast without hurting the lawn grasses. If you have a large infestation,
a complete renovation of the lawn may be necessary. In this case, make
sure all the quackgrass is dead before you put down new seed.
Q: I have a Christmas
cactus that bloomed very nicely twice a year. It was always located in
a south window. Last year, after the Easter blossoms fell off, I had to
transplant it. It was too tall for its pot, so I transplanted it into
a bigger pot. It is growing nicely but there were only two blossoms on
it for Christmas and none for Easter. I have been giving it fertilizer.
(Gackle, N.D.)
A: Be patient. The
plant needs to get a little pot-bound to help it bloom. This fall, around
the end of September, start covering the plant. Cover it at 5 p.m. and
uncover it at 7 a.m. You should see plenty of flower buds developing
after six to eight weeks.
Q: I have a potted
gerbera daisy that has flowers that droop and then stand back up again.
Is this normal? Now the flowers have drooped and remained that way. Should
I deadhead the flowers? Will the plant bloom again? Is a potted gerbera
considered a perennial? (E-mail reference)
A: The gerbera daisy
is treated like an annual, although it is perennial in the south. I
would remove the blooms and get the plant outdoors or in a sunny window
for the summer. Fertilize it during active growth with something like
Miracle-Gro. Keeping it as a potted indoor plant will make it a short-lived
plant. Planting it outdoors for the summer will at least give you the
beauty of the blooms until frost.
Q: I read about salt
in a dog’s urine killing grass. Mine is in bad shape. It is especially
bad during the winter when they want to go in the same area all the time.
I have to start over every year with new sod. Is there something I can
do or are there any particular grasses that can withstand the heavy concentration
of dog urine? (E-mail reference)
A: If I knew the
answer or if anybody did, it would be announced all over the world.
I would try growing decent grass by using a sandy base. You are then
identifying the area for what it is, a toilet area for your dog.
Q: I have some white
and some red amaryllis. This year when they bloomed they were all white.
Do different colored amaryllis need to be planted separately or can they
be planted near each other? The only thing I have been able to figure
out is that they have cross-pollinated and become one color. (E-mail reference)
A: Obviously something
happened that got them to revert to white flowers. It could be that
only the white amaryllis flowered. It could be that they crossed and
the white flower is the dominant gene or they set seed and only the
white seed was viable and germinated. It’s possible the red was
a sport (chimera) and it was lost or destroyed with the reflowering.
Finally, the red amaryllis may have died and only the white survived
and flowered.
Q: If you have ivy
growing on a brick wall, in time, does the ivy damage the bricks and mortar?
(LaMoure, N.D.)
A: In time, yes.
But, the damage is slight and only after a great deal of time has passed,
probably 25 to 30 years (unless it is a poor brick and mortar job).
The problem usually arises when the owner tries to remove the old vine
and finds the aerial holdfasts are anchored into the wall. Thats when
the wall comes tumbling down in bits and pieces.
Q: I moved onto a
property that has lilac bushes. The previous owner transplanted them approximately
three years ago from established bushes on another property. The bushes
are about two feet tall. The previous owner told me that each year the
bushes get green leaves but do not flower. These bushes appear to be alive,
so I want to save them. (E-mail reference - Rush City, Minn.)
A: I’m guessing
they are planted too deep. Try pulling some soil away from the crown
to see if that helps. You will not get results right away, but you should
see some next year. If the plants do not respond to this treatment,
rip them out and replace with new lilac shrubs. Life is too short to
wait for a pouting lilac to decide to bloom!
Q: Can you tell me
if keeping flowers in a vase made of silver is good for them? I tried
it once with tulips and they seemed to do fine, but when I finally threw
them out, I noticed that the stems in the vase were completely shriveled
shut. It looked like the plant was trying to keep water out. But, the
tulips looked beautiful and lasted longer than tulips bought on the same
day which were kept in a glass vase. Am I torturing the plant into lasting
longer? (E-mail reference)
A: Silver thiosulphate
is known to extend the life of cut flowers in a vase. I doubt the flowers
are being tortured into lasting longer. Enjoy their beauty.
Q: There are wild
roses growing in a corner of my garden, which I love. However, for the
past two summers they have been cursed by what looks like spatters of
bright orange paint followed by the browning and drying of the leaves.
Do you know what this might be? (E-mail reference)
A: What you are
seeing is rust fungus on the foliage. When the pathogen starts to appear,
pick off and destroy the infected leaves, and spray with a fungicide
containing mancozeb (Dithane) or simply spray with lime-sulfur. If the
roses are still dormant at this time, spray with lime -sulfur. Repeat
the application as weather conditions warrant.
Q: Upon returning
from the south, we found burrowing in our lawn and a great deal of dead
grass. We suspect it is the work of skunks as this happened to our neighbor
several years ago. We live on a lake in a rural area. I purchased Carbary
some time ago but did not apply it. Would an application of Carbary be
helpful at this time? It appears the mischief is done at night. Would
illuminating the area at night be of any advantage? We have a global arborvitae
that animals have chewed off a good one and a half feet from the bottom
leaves. I’ve never had that happen before. (Pickerel Lake, S.D.)
A: Sorry, I don't
know what "Carbary" is. Keeping snacking animals at bay usually
works by using hot pepper spray. You’ll need to reapply it after
rainy periods. Skunks and other rooting animals are looking for grubs
so your lawn is a good supper for them. You could get your lawn treated
with Bt which is a biological insecticide that would slowly reduce the
grub population. It would not pose a hazard to other wildlife in the
area or upset the soil's ecosystem.
Q: Sorry, but I spelled
the chemical wrong. It is spelled Carbaryl (1-natchthyl N-methylcarabamate).
Maybe you are familiar with it.
A: Carbary1 is more
popularly known as Sevin. You can use it to control grubs but be sure
to water it in.
Q: We have a long
row of spruce evergreens that run east to west. They are 12 to 15 years
old so they are well established. This past winter was evidently hard
on them as several have developed very brown needles. I was informed that,
if it is a disease, we might have to remove them. That would be sad as
it takes so many years to get to that size. I would appreciate your thoughts
or suggestions on this problem. (Tower City, N.D.)
A: I would suggest
waiting to see if you get new growth in the next month or so. It is
likely winter damage but, if the evergreens are well established, they
will not succumb to this past winter's harshness. You can check the
buds and see if they are still green (use your thumbnail to break into
them). If they are still green, new growth will emerge later this spring
and eventually the burn you are seeing will disappear. You might want
to water them once a week to help them along if we continue to go without
sufficient rain.
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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