Frequently Asked Questions

Question:
Are broadleaf herbicides effective when applied during dry weather?
Answer:

Broadleaf herbicides are most effective when applied to weeds that are actively growing.  During prolonged periods of dry weather, some weeds are likely to curl up or wilt.  An application of a broadleaf herbicide to drought stressed...

Question:
There are tiny holes in my eggplant foliage. What should I do?
Answer:

The tiny holes are likely due to flea beetles.  Flea beetles are the most common pest of eggplant in the home garden.  Adults are tiny, shiny, black beetles.  They possess large hind legs that enable them to jump.  Flea...

Question:
How do I control bagworms on my spruce tree?
Answer:

Bagworms are caterpillars that live inside spindle-shaped bags.  (The bags somewhat resemble small Christmas tree ornaments hanging from the tree.)  Bagworms feed on the foliage of a wide variety of trees and shrubs.  However, they...

Question:
How do I take geranium cuttings?
Answer:

Using a sharp knife, take 3- to 4-inch stem cuttings from the terminal ends of the shoots.  Pinch off the lower leaves, then dip the base of each cutting in a rooting hormone.  Stick the cuttings into a rooting medium of vermiculite or...

Question:
What is the best way to store carrots?
Answer:

After harvesting carrots, cut off the green tops one-half to one inch above the roots.  Small amounts can be placed in perforated plastic bags and stored in the refrigerator.  Large amounts can be buried in sand or sawdust and then...

Question:
The leaves on my river birch are yellow-green. Why?
Answer:

In Iowa, the foliage of the river birch (Betula nigra) often turns a sickly yellow-green. The yellow-green foliage is due to a deficiency of iron. The problem is referred to as iron chlorosis. (A close examination of chlorotic leaves...

Question:
What are some good switchgrass varieties for the home landscape?
Answer:

Switchgrass (Panicum virgatum) is a native prairie grass.  It is typically found in moist sites, such as along the banks of streams, and grows 3 to 6 feet tall. 

Several switchgrass cultivars are excellent plants for the...

Question:
Why are my tomatoes cracking?
Answer:

Fruit cracking is a common problem on tomatoes.  Cracks usually appear at the top or stem end of the fruit.  Cracks radiate out from the stem (radial cracks) or circle the fruit in concentric rings (concentric cracks).  Fruit...

Question:
Which perennials can be divided in late summer?
Answer:

The best time to divide perennials varies with the different plant species. While most perennials are best divided in early spring, late summer/early fall (September in Iowa) is a good time to dig and divide peony, daylily, garden phlox, hosta,...

Question:
When should I harvest garlic?
Answer:

Harvest garlic when the foliage begins to dry.  In Iowa, garlic is usually harvested in August or September.  Carefully dig the bulbs with a garden fork or shovel.  Dry the garlic in a warm, dry, well-ventilated location. ...

Question:
Is it safe to plant currants and gooseberries in home gardens in Iowa?
Answer:

Early in the 1900's, white pine blister rust (Cronartium ribicola) became a serious disease problem in the United States.  White pine blister rust requires both a currant or gooseberry (Ribes species) and white pine to...

Question:
I saved last year's poinsettia. How do I get it to flower for Christmas?
Answer:

Poinsettias are short-day plants.  Short-day plants grow vegetatively during the long days of summer and produce flowers when days become shorter in fall.  In order for poinsettias to flower for Christmas, they must receive complete...

Question:
What is the proper mowing height for shady turfgrass areas?
Answer:

Do not mow shady areas less than 3 inches in height.  Because of the lower photosynthetic rates in shady areas, the turfgrass plants need a large leaf surface to manufacture adequate amounts of food.  The recommended mowing height for...

Question:
How can I tell dead canes from live shoots when pruning raspberries in late winter?
Answer:

Dead raspberry canes will be white to gray in color.  When dead canes are pruned, the tissue inside the stem will be tan to brown and dry.  Live canes will be brown to purple in color.  The tissue inside the stem will be white to...

Question:
What is the proper way to plant a container-grown tree?
Answer:

When planting a container-grown tree, dig a hole that is 2 to 3 times wider than the diameter of the container.  The depth of the hole should be 2 or 3 inches less than the height of the soil ball.  Slope the sides of the hole so the...

Question:
There are round, circular spider webs are on my lawn. What should I do?
Answer:

The horizontal circular webs were created by various spiders collectively called grass spiders.  They are harmless to the grass and ecologically beneficial as predators.  The webs accumulate between rain showers and mowings.  They...

Question:
How can you tell when a muskmelon is ripe?
Answer:

The fruit of the muskmelon or cantaloupe is mature when the stem slips easily from the melon with slight pressure.  The melon is not ripe if the stem has to be forcibly separated from the fruit.  Other indicators of maturity are based...

Question:
There are big, hairy worms and tent-like structures in my walnut tree. What are they and how do I get rid of them?
Answer:

The “worms” are likely fall webworms.  Fall webworms are hairy, tan to yellow caterpillars.  As they feed, fall webworms construct tents or webs at the ends of branches.  Tents are initially small, but the caterpillars enlarge the...

Question:
I planted a Martha Washington geranium outdoors in spring. Unfortunately, it didn't bloom all summer. Why?
Answer:

Martha Washington or regal geraniums (Pelargonium x domesticum) produce beautiful flowers.  Unfortunately, cool (50 to 60°F), night temperatures are required for flower formation.  Few flowers form during the summer...

Question:
When should I harvest rutabagas?
Answer:

Harvest roots when 3 to 5 inches in diameter.  The foliage may also be harvested for greens.  Prior to storage, trim off the foliage to within 1 inch of the crown with a sharp knife.  Also remove the tap root.  Rutabagas...

Question:
This fall some of the needles on my white pines have turned yellow and begun dropping to the ground. Is this a problem?
Answer:

The loss of needles is probably due to seasonal needle drop. Deciduous trees, such as maple and ash, drop all of their leaves in fall. Though it largely goes unnoticed, evergreens also lose a portion of their foliage (needles) on a yearly basis....

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

Peonies perform best in full sun and well-drained soils.  When selecting a planting site, choose a location that receives at least 6 hours of direct sun each day.  Avoid shady areas near large trees and shrubs.  Poorly drained...

Question:
How can I prevent blight on my tomatoes?
Answer:

Foliar diseases of tomatoes are a common problem in the home garden.  Fungal diseases, such as early blight and Septoria leaf spot, overwinter on plant debris in the soil.  Fungal spores are splashed onto plant foliage by raindrops or...

Question:
How should I prepare my perennial beds for winter?
Answer:

Perennial plants can be cut back in fall after the foliage has been destroyed by a hard freeze.  Compost the plant debris. While this work can be done, it is not necessary to clear cut the perennial garden after the first freeze of the...

Question:
How do you store garlic?
Answer:

After harvesting the garlic, dry the garlic in a warm, dry, well-ventilated location.  Place the garlic on an elevated wire screen or slotted tray to promote drying.  When the tops have dried, cut off the dry foliage 1 inch above the...

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