Frequently Asked Questions

Question:
How can I prevent deer browsing and feeding during the winter months?
Answer:

Deer may feed on trees and shrubs during the winter months and severely damage or destroy plants.  Damage is most likely to occur when food is scare during prolonged periods of snow cover.  Deer often feed on the foliage on the lower...

Question:
I recently purchased a primrose at a florist. How do I care for it?
Answer:

Primroses (Primula species) are typically sold at florist shops and greenhouses in late winter or early spring.  Plants produce attractive, 1- to 1½- inch-diameter flowers above a rosette of leaves.  Flowers may be white,...

Question:
Why does my fig tree lose some of its leaves during the winter?
Answer:

Environmental conditions indoors during the winter months are often rather poor.  Low light levels, cold drafts, low relative humidities, and other environmental factors are stressful to plants.  The stressful conditions may cause figs...

Question:
The leaves on my houseplant are covered with a sticky sap. There are also small "bumps" on the stems. What is the problem?
Answer:

The houseplant may be infested with scale insects.  These small, inconspicuous insects are covered with shell-like coverings.  They attach themselves to stems or leaves and suck sap from the plants.  As they feed, the scale insects...

Question:
What is the proper way to prune a large tree branch?
Answer:

To prevent extensive bark damage, use a 3-cut procedure when pruning branches that are greater than 1½ inches in diameter.  Make the first cut 6 to 12 inches from the main branch or trunk.  Cut upward and go about one-third of the way...

Question:
Sap is flowing from a pruning cut on my maple tree. Should I be concerned?
Answer:

Some tree species, such as maple, birch, and elm, “bleed” heavily when pruned in late winter or early spring.  However, the loss of sap does not harm the trees.  The trees will not “bleed” to death.  Eventually the flow of sap will...

Question:
My onions don't store well. Why?
Answer:

The storage life of onions is largely determined by the variety (cultivar), harvesting and drying procedures, and storage conditions. 

When selecting onions, choose varieties that store well, such as ‘Copra,’ ‘Stuttgarter,’ and ‘Sweet...

Question:
When is the best time to prune oak trees?
Answer:

Winter (December through February) is the best time to prune oak trees in Iowa.  Pruning oak trees in winter greatly reduces the risk of an oak wilt infection. 

Oak wilt is a fungal disease that is lethal to many oaks.  It...

Question:
Why are my potatoes beginning to sprout?
Answer:

Potatoes should be stored at a temperature of 40 degrees Fahrenheit and relative humidity of 90 to 95 percent.  Tubers often begin to sprout if storage temperatures are above 50 degrees F.  Also, don’t store potatoes with apples or...

Question:
Which plants are most likely to be damaged by browsing rabbits in winter?
Answer:

Trees and shrubs that are often damaged by rabbits in winter include crabapple, apple, pear, redbud, honey locust, serviceberry, burning bush or winged euonymus, flowering quince, barberry, roses, and raspberries. Small evergreens (especially...

Question:
My acorn squash turn yellow during storage. Why?
Answer:

The problem may be improper storage.  Acorn-type squashes should be stored at a temperature of 50 to 55 degrees Fahrenheit.  Some acorn-type squashes will turn yellow when stored at temperatures above 55 degrees Fahrenheit.  High...

Question:
There are black growths on the branches of my chokecherry. What should I do?
Answer:

The black growths are probably black knot.  Black knot is a fungal disease that occurs on chokecherry, European birdcherry, and several other wild and cultivated cherries and plums.  The black growths (galls) can vary from a few inches...

Question:
What would be a good planting site for butterfly weed?
Answer:

The butterfly weed (Asclepias tuberosa) is a member of the milkweed family.  Plants grow 2 to 3 feet tall and produce flat-topped clusters of bright orange flowers from July through September.  Their flowers attract several...

Question:
Which trees and shrubs provide food for birds during the winter months?
Answer:

When attempting to attract birds to the landscape, trees and shrubs that provide food during the winter months are extremely important as natural foods are most limited at this time of year.

Trees that provide food for birds in winter...

Question:
Which perennials are most likely to be heaved up out of the ground in winter?
Answer:

Repeated freezing and thawing of the soil during the winter months can lift up or heave some perennials out of the soil.  Heaving exposes the plant’s crown and roots to cold, dry air.  Perennials that have been heaved up out of the...

Question:
Which trees and shrubs have colorful fruit in winter?
Answer:

The drab winter landscape can be brightened with several trees and shrubs with colorful, persistent fruit.

Trees and shrubs with colorful fruit in winter.
Common Name ...
Question:
When should I start tuberous begonias indoors?
Answer:

Plant tuberous begonia tubers indoors 8 to 10 weeks before the average last spring frost in your area.  (Flowering typically begins 12 to 14 weeks after planting.)  Start tuberous begonias in pots or other suitable containers.  All...

Question:
Which shrubs have attractive bark in winter?
Answer:

One of the most beautiful sights in winter is the bright red twigs of redosier dogwood (Cornus sericea) set against a backdrop of newly fallen snow. Native to Iowa, the redosier dogwood grows 6 to 10 feet tall. Several colorful varieties...

Question:
My African violets aren't blooming well. Why?
Answer:

The African violets may not be receiving adequate light.  The proper amount of light is essential for good bloom.  Generally, windows with north or east exposures are best for African violets.  However, if these exposures are not...

Question:
How do I care for a poinsettia?
Answer:

Place the poinsettia in a plant sleeve or carefully wrap it before transporting the plant home.  Exposing the poinsettia to freezing temperatures, even for a few minutes, may cause its bracts and leaves to blacken and drop.  As soon as...

Question:
Is the poinsettia poisonous?
Answer:

The poinsettia has long been regarded as poisonous.  However, research conducted at various institutions has shown the poinsettia is not poisonous.  While the poinsettia is not poisonous, it is not intended for human or animal...

Question:
How do you care for a cineraria?
Answer:

The cineraria (Pericallis x hybrida) is a flowering plant that is typically sold at floral shops and other retailers from mid-winter to early spring.  Plants produce clusters of 1- to 3-inch-diameter, daisy-like flowers....

Question:
How do you care for a gloxinia?
Answer:

The gloxinia (Sinningia speciosa) is a flowering houseplant that’s related to the African violet.  Plants produce large, velvety, bell-shaped flowers that may be white, pink, red, purple, or blue.  Gloxinias are commonly sold...

Question:
How do I care for a calceolaria or pocketbook plant?
Answer:

Place calceolarias in a brightly lit, cool location.  The location should receive bright light, but not direct sunlight.  Ideal temperatures are 60 to 65 degrees Fahrenheit.  Check the potting soil daily.  When the surface of...

Question:
My shrubs are flopping over due to the weight of heavy, wet snow. What should I do?
Answer:

The weight of heavy, wet snow can cause considerable damage to small trees and shrubs.  When heavy, wet snow accumulates on small trees and shrubs, gently shake the snow from their branches or carefully brush off the snow with a broom....

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