|
March
9, 2006
Hortiscope
Ronald C.
Smith, Horticulturist
NDSU Extension Service
Q: I have a heritage
river birch (three clumps) that I planted 12 years ago. The tree is 7
feet from my basement wall. I haven't been concerned about foundation
damage until I noticed a crack in the mortar on the blocks closest to
the tree. There are no other cracks in any of the basement walls. Should
I be concerned that the tree may be damaging my foundation? (e-mail reference)
A: The best way
to find out is to do a little digging this spring. If there is a root
pushing against the foundation, cut it out, seal any cracks with water-proofing
sealer and place a root barrier between the cut root and the foundation.
If the root isn't there, I'd still suggest sealing the crack to prevent
any moisture from getting in there and causing problems. My birch tree
is about the same distance from our foundation, but I have not found
any extensive root activity or any evidence of damage.
Q: I have had a poinsettia
plant for about three months. I repotted it not too long ago and now there
is very thick mold growing around the bottom of the pot. The mold has
started spreading to the topsoil. This is puzzling to me because poinsettias
don't need much water, so I know it is not overwatered. How do I get rid
of the mold? Is the mold harmful to my plant? (e-mail reference)
A: This is a saprophytic
mold, not a parasitic type. It is "digesting" the organic
matter in the potting soil and on the surface of the pot. It will not
hurt the plant. The best way to be rid of it is to scrub it off the
container and loosen the soil in the pot with a cultivator. It doesn't
take much moisture to get this kind of mold to grow, so I would suggest
that you add another day or two between your current watering cycles
to encourage drying. Moving the plant outdoors this spring, after the
danger of frost has passed, will help you get rid of this problem.
Q: I have a flowering
crab that has overgrown the area it is planted in. I need to prune it.
From what I have read, the best time to prune is late winter. How much
can I prune off the tree without killing it? (e-mail reference)
A: You are correct
in saying that late winter or early spring is a good time for pruning
most deciduous trees, including flowering crabs. A basic rule of thumb
is to prune no more than 25 percent to 30 percent of the total canopy
during a growing season. This is because it would result in too much
sucker growth that would literally negate your efforts for improvement
pruning. If this is a tree that never has been pruned, don't yield to
the temptation to get in there and "clean it up" from years
of neglect! Remove the crossing-over branches, any that have "self-grafted"
and any that are diseased, dead or damaged. In subsequent years, prune
to open the crown for better air and sunlight penetration and more aesthetic
appeal.
Q: I found your Web
site and was so happy to see that you might be able to help me. I have
a lilac tree growing in my backyard. It flowers beautifully, but the flowering
is brief. Is that common? I want to move the tree because it blocks access
to the yard. Can I do that or should I try to take a cutting and root
it as you say on your Web site? If I do the cutting and replant, how long
will it take the tree to grow and flower? I must admit I do not have a
green thumb, but I'd really like to save the tree because I enjoy it so
much. (e-mail reference)
A: Lilacs that size
do not enjoy being moved, so you are better off attempting to propagate
it or taking the easier route by purchasing another lilac. I suggest
the latter since you admit to not having a green thumb. The length of
bloom of most spring flowering shrubs is usually dictated by the weather.
If it is cool and breezy, the blooms will last longer. If it is hot
and windy, the blooms won’t last as long.
Q: I have a ficus
tree that is more than 21 years old. I had it on a porch during the summer
months and brought it in for the winter. I have noticed that it drops
leaves, which is probably due to the move and temperature change. Some
of the leaves that drop are yellowed and some are green. Also, I have
noticed a black, spotted substance, as if dirt was splattered on it. I'm
wondering if that is truly dirt from the porch or a type of insect residue.
As soon as the weather warms, I plan to take it outside and hose it off
and treat it with Safer soap before putting it back on the porch. Any
other suggestions? (e-mail reference)
A: Leaf drop is
normal with ficus after just about any move. The spotting, assuming
it wipes off, could be insect droppings. I encourage you to closely
examine the plant to see if you can find evidence of insect activity
or the insects themselves. Your procedure sounds like a good one to
follow and a good one to initiate before bringing the ficus in for the
winter.
Q: I would like the
names of different types of plants that can grow or survive with the roots
emerged in water. I want to take a large, clear vase and decorate it with
rocks and sea shells at the bottom, put a couple of tropical fish in it
and have the plant growing out of the vase. (e-mail reference)
A: Many plants will
do fine in a water medium. The water needs to be changed or aerated
on a regular basis to keep toxins from building up. Of course, nutrients
will need to be added on a spoon-feeding basis to keep the system going
for any significant period. I've seen bamboo, African violets, spider
plants, lilies, avocados and more thriving with their roots in water
and maintained properly. Other than cacti and succulents, the choice
is yours!
Q: I was reading your
questions and answers on schefflera in search of a treatment for a painful,
itchy rash I developed from the one in my front yard. I have to say I
was surprised to see how many people adore the plant. I want to destroy
mine because every time I work in the yard near it, I break out into a
horrible rash within a couple of days. Even when I wear long sleeves and
gloves, I get a rash somewhere. The rash lasts at least a week and is
a lot like poison ivy rash. Have you heard of any treatments? I know you're
a plant expert and not a doctor, but I thought maybe you would have heard
of something. I've tried calamine lotion and Benadryl, but got no relief.
Ivarest seems to help a little. Also, I've noticed this tree's roots have
spread toward the foundation of our house and seem to have strangled to
death nearby hibiscus plants. Is this possible? Could the roots pose a
problem for our foundation and water pipes? I know this won't go over
well with schefflera lovers, but how can I get rid of this thing? I was
very disappointed to read that cutting it back to a few inches above the
ground won't kill it. I would set mine on fire if it weren't so close
to the house. I was thinking I could cut it down and spray the trunk with
Roundup. Am I the only person in the world who despises this plant? (e-mail
reference)
A: The distinction
is yours, but I'm sure others will come forth now that you have broken
the code of silence. I wouldn't mess around any longer if I were you.
I would suggest going to a dermatologist and describe your problem.
You want to get something that will counter any future reactions as
quickly as possible. Hire a professional to come out and remove the
entire plant, including the roots. Even if the schefflera is dead, you
still can get a reaction to it, so make sure the contractor removes
all the roots.
Q: Do you know the
Latin name for the corkscrew plant? Will it grow in Zone 3? (e-mail reference)
A: You probably
are referring to the corkscrew willow, Salix matsudana Tortuosa. It
is not hardy in Zone 3. If used, it should be planted in a protected
location. Sometimes, one can gain a hardiness zone or two using good
microclimate manipulation.
Q: Your Web site at
www.ext.nodak.edu/extnews/hortiscope/flowers/tulip.htm
was a great find! Thank you for the comprehensive column. Over the
last few years, I have fallen helplessly in love with tulips! Your column
answered almost all of my questions. I have three pots of tulips at home
that have finished blooming. I have removed the deadheads at the base
and am waiting for the green foliage to die. (e-mail reference)
A: Keep the tulips
moderately moist until the foliage begins to yellow and then stop watering
to allow the bulbs to dry. You can store the bulbs in a cool, dark location
and in dry soil until this fall and then plant them outdoors for next
spring. If your intent is to use them as potted tulips, take them out
of the pots after they dry. Keep them in a dry, cool, dark location
until about 60 days before you want to begin bringing them to flower.
At that time, place them in the vegetable crisper surrounded by sphagnum
peat moss (milled or unmilled) or moist sand. When new growth appears
at the tips, repot and place them where you want to show them off. Try
to keep them in a cool environment to extend the flowering period.
Q: When is the best
time of year to trim a flowering crabapple tree? And how much do you trim
back? Part of the top broke off in a bad storm last year, so now it looks
out of balance. (e-mail reference)
A: Pruning can take
place anytime before spring growth. Prune off no more than 25 percent
to 30 percent of the total crown area. Clean up the area where there
were some broken limbs to prevent disease or rot from setting in.
Q: I have had a peace
lily in my office for almost a year. It has a lot of clear, sappy stuff
on the leaves and stems. It doesn't wipe off easily with just water. Do
you know what this substance is? There also is a lot of browning on the
tips. How can I get rid of this as well? (e-mail reference)
A: This is an indication
of insect or mite feeding activity somewhere on the plant. It could
be coming from the underside of the leaves or at the point where the
stem expands into a leaf. You need to get some insecticidal soap, which
is usually available from the Safer or Schultz Co. Soak a rag in the
soap and wipe the leaves on both sides. While you are at it, examine
the entire plant to see if there is any evidence of insects, such as
scale (little bumps), that are not easily wiped off. If there is evidence,
you will have to come back with a cotton-tipped swab soaked in the soap.
If the infestation is too heavy, you might be better off getting rid
of the plant. Concerning the brown tips, this is usually evidence of
excessive fertilizer salts or fluoride in the water.
Q: I just moved in
a house where the previous owners left two flourishing devil's ivy plants.
When we moved in two weeks ago, they were both very green and healthy
looking plants. Now the leaves on the ivy in the most-lit room are getting
yellow, limp, have little holes, and cracks are forming. This plant is
suspended in a plastic pot. The plant does not have proper drainage. There
also is a white overgrowth at the base of the plant near the soil, which
is almost fungi-looking. What should I do? Is there a product for this
kind of problem? Thanks for your help. (e-mail reference)
A: Did you change
the location of the plants, interior temperature or watering practices?
If they were flourishing two weeks ago, but are now looking limp, a
major event must have occurred. Plants almost always never decline that
quickly unless something has served as a "trigger." You can
try repotting in fresh potting soil and contacting the previous owner
to see what it was the person did to keep the plants flourishing. Devil’s
ivy usually is an easy plant to care for because it thrives on very
little care, but still looks decent.
Q: I received a minirosebush
this Christmas that was full of blossoms. All the blooms have fallen off
and are not growing. Do roses only bear blooms at a certain time of year?
When should I plant it outside? (e-mail reference)
A: The rose will
flower again when it has enough energy. You can plant it outside when
the danger of a killing frost is past.
Q: I have been caring
for a violet plant for about three months for the first time in my life.
I love its looks, but have heard how difficult they are to grow. The plant
has grown quite large, so I decided to transplant it. While transplanting,
I snapped the neck between the leaves and the roots. I left it in the
soil, hoping it won’t die. Is there anything I can do to save the
plant? It is a beautiful plant, so I hope I did not kill it. (e-mail reference)
A: Take some of
the leaves and root them. The crown also should root for you. For plant
propagation information, go to my Web site at www.ext.nodak.edu/extpubs/plantsci/landscap/h1257.pdf.
By the way, these plants don't deserve the reputation they have of being
difficult to grow, so don't let that scare you!
###
Source: Ron
Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu
|
