Frequently Asked Questions

Question:
When can I divide daylilies?
Answer:

Daylilies can be divided in early spring (as new growth begins to emerge) or in late summer.  Dig up the entire clump with a spade.  Shake or wash off the soil.  Then carefully pull the clump apart.  Oftentimes, a sharp knife...

Question:
What is the proper way to divide peonies?
Answer:

September is the best time to divide peonies.  By September, peony plants have been able to store adequate food reserves in their roots.  Also, the replanted divisions have several weeks to get reestablished at their new sites before...

Question:
When is the best time to transplant peonies?
Answer:

September is the best time to transplant peonies.  Begin by cutting the peony stems near ground level.  Then carefully dig around and under each plant.  Try to retain as much of the root system as possible. 

If desired...

Question:
When can I cut back peony foliage?
Answer:

Cut back peony foliage after it has been destroyed by a hard freeze.  In Iowa, late October or early November is generally a good time to cut back peonies.  Cut off the stems near ground level.  If the peonies experienced foliar...

Question:
When would be a good time to dig and divide lilies?
Answer:

Early fall is an excellent time to dig and divide Asiatic, Oriental, and other garden lilies.  Carefully dig up the clump and separate the bulbs.  Replant the bulbs immediately.  (If planting must be delayed, place the bulbs in a...

Question:
What are the black spots or blotches on my apples?
Answer:

The problem may be sooty blotch and flyspeck.  Sooty blotch and flyspeck are 2 different fungal diseases that often occur together on apples.  Sooty blotch appears as dark brown to black, ½ inch or larger smudges on the surface of the...

Question:
There is a large growth on the trunk of my maple tree. What is it?
Answer:

The growth on the trunk of the maple tree is likely a burl.  Burls are abnormal swellings or growths that develop on the trunks and branches of trees.  Burls can be found on deciduous trees and evergreens.  The exact cause is...

Question:
There are golf ball-sized growths with horn-like projections on the branches of my pin oak. What are they?
Answer:

The growths on the pin oak are a type of gall.  Galls are abnormal growths of plant tissue induced to form by mites, insects, or other small organisms.  The galls on the pin oak are called horned oak galls because of the horn-like...

Question:
How do I stop yellowjackets from feeding on my raspberries?
Answer:

Yellowjackets are social wasps that build paper nests in the ground, a log, building wall, attic, or other sites.  The workers from the colony travel up to a few hundred yards from the nest while looking for food.  In early summer, the...

Question:
There are small, white worms in my raspberries. What are they and how can they be controlled?
Answer:

The small, white worms are likely the larvae of the spotted wing drosophila.  Spotted wing drosophila adults are small, yellowish brown flies.  Males have distinctive dark spots on their wings, hence the name spotted wing drosophila....

Question:
There are small, black beetles feeding on my raspberries. What can I do?
Answer:

The small, black beetles are likely sap beetles.  They are also known as picnic beetles or picnic bugs.  Sap beetles commonly feed on over-ripe or damaged fruits and vegetables in the garden.  

Sanitation is the best...

Question:
How do you store grapes?
Answer:

Sound grapes can be stored in perforated plastic bags in the refrigerator for up to two months. Optimum storage conditions are a temperature of 31 to 32 degrees Fahrenheit and a relative humidity of 85 percent. 

Question:
Is late summer/early fall a good time to plant trees?
Answer:

Mid-August through September is an excellent time to plant pine, spruce, and other evergreens.  (Evergreens planted in late October or November may not have adequate time to become established before the onset of winter and could be subject...

Question:
Which vegetables can be planted in late summer?
Answer:

Several vegetables can be planted in late summer for a fall crop.  For a fall crop, plant beets, carrots, Swiss chard, kohlrabi, and kale in early to mid-August, plant leaf lettuce and spinach in late August to early September, and plant...

Question:
There are white, raised spots on my potatoes. Why?
Answer:

The white, raised spots on your potatoes are probably swollen lenticels due to wet soil conditions.  Potato tubers are enlarged underground stems.  Lenticels are small openings in the tuber surface that allow for gas exchange. ...

Question:
My peonies appear to be covered with a white, powdery substance. What is it?
Answer:

The white, powdery material on the peony foliage is powdery mildew.  Powdery mildew is a fungal disease.  Powdery mildew occurs on a large number of plants (peonies, lilacs, viburnums, roses, garden phlox, bee balm, turfgrass, and many...

Question:
Why are some of my cucumbers misshapen?
Answer:

Poorly-shaped fruit are usually the result of poor pollination.  Poor pollination may be due to cool, wet weather and improperly applied insecticides that limit bee activity.  When insecticides are necessary, select an insecticide with...

Question:
Why are some of my cucumbers bitter?
Answer:

The bitterness in cucumbers is produced by the compound cucurbitacin.  Cucurbitacins are normally found in the leaves, stems, and roots of cucumber plants.  The cucurbitacins spread from the vegetative parts of the plant into the...

Question:
My tomato plants are flowering, but aren’t setting fruit. Why?
Answer:

Unfavorable weather conditions are the primary reason for blossom drop on tomatoes.  High daytime temperatures (above 85 degrees Fahrenheit) and low nighttime temperatures (below 55 degrees Fahrenheit) interfere with pollination, causing...

Question:
My hot peppers are setting fruit, but not my bell peppers. Why?
Answer:

In regards to fruit set, bell peppers are sensitive to high temperatures.  The optimum temperature range for flowering and fruit set on bell peppers is between 70 and 80 degrees Fahrenheit.  Hot peppers tolerate high temperatures much...

Question:
There are wart-like growths on the undersides of the leaves on my hackberry. What are they?
Answer:

The wart-like growths on the hackberry leaves are galls.  Galls are abnormal growths of plant tissue induced to form by mites, insects, or other small organisms.  They are quite common on trees.  

The gall found on the...

Question:
There are white, fuzzy objects on the branches of my maple tree. Are they harming the tree?
Answer:

The white, fuzzy objects on the branches of your maple tree are wooly alder aphids.  (The insect is also known as the maple blight aphid.)  Wooly alder aphids feed on the sap of maple trees from bud-break until late June.  Then...

Question:
How do I control grasses in my iris bed?
Answer:

Annual grasses, such as crabgrass and foxtail, can be controlled by hand pulling.  

Perennial grasses, such as quackgrass, are much more difficult to control as they spread via underground stems or rhizomes.  (All of the rhizomes...

Question:
When should I divide my perennials?
Answer:

The best time to divide perennials varies with the different plant species.  Early spring (just as new growth begins to appear) is the best time to divide aster, chrysanthemum, hosta, bee balm, sedum, yarrow, obedient plant, and ornamental...

Question:
How do I germinate butterfly weed seeds?
Answer:

Harvest the seed pods of butterfly weed when the pods begin to split.  Seeds can be sown directly outdoors in late fall or started indoors.  

When sowing seeds outdoors, work up the soil in a protected location in early to mid-...

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