Frequently Asked Questions

Question:
What are some good low-growing groundcovers?
Answer:

Plant heights vary somewhat based on the growing conditions at the site.  However, there are several groundcovers that are 12 inches or less in height. 

Shade Groundcovers

Low-growing groundcovers for shade include:...

Question:
When should I harvest beets?
Answer:

Beets may be harvested when the roots are 1 inch in diameter.  However, the main crop usually isn’t harvested until the roots are 1½ to 3 inches in diameter.  (Beets larger than 3 inches in diameter are often tough and fibrous.) ...

Question:
I need to have some tree work done. How do I select a qualified arborist?
Answer:

Trees are valuable assets to the home landscape.  Occasionally the services of a professional arborist are needed to prune a large tree or assess the condition of a tree after a storm.  For many individuals, selecting an arborist is a...

Question:
What can I use as a mulch around my tomato plants?
Answer:

Several organic materials can be used as a mulch around tomato plants.  Suitable mulching materials include:

  • Dry grass clippings (Do not collect grass clippings from lawns that have been treated with a broadleaf herbicide...
Question:
Several new shoots on my crabapple have turned brown and wilted. What is the problem?
Answer:

Fire blight is probably responsible for the wilted shoots on your crabapple.  Fire blight is caused by  the bacterium Erwinia amylovora.  Plants susceptible to fire blight include apple, crabapple, pear, hawthorn, and...

Question:
What are the benefits of aerating the lawn?
Answer:

Aeration relieves soil compaction, improves water and nutrient movement in the soil, and prevents thatch accumulation.  Aeration improves the growing conditions for the turfgrass plants and results in a healthier, more vigorous lawn. ...

Question:
How do I control weeds in my asparagus planting?
Answer:

Weeds compete with asparagus for light, water, and nutrients and will reduce asparagus yield and quality if not controlled. Cultivation and hand pulling are the best ways to control weeds in an asparagus planting.  Hoe or...

Question:
How often should I water my roses?
Answer:

Modern roses, such as hybrid teas, floribundas, and grandifloras, require watering during hot, dry weather.  The frequency depends upon weather conditions and soil type.  In most gardens, a thorough watering every 7 to 10 days during...

Question:
What are some good raspberry varieties for Iowa?
Answer:

Suggested raspberry varieties for Iowa include:

Summer-Bearing Red Raspberries for Iowa

  • ‘Boyne’
  • ‘Latham’
  • ‘Killarney’

Fall-Bearing Red Raspberries for Iowa

...
Question:
The leaves on several of my hostas have turned yellow, then brown, and finally collapsed onto the ground. What is happening to my hostas?
Answer:

The hostas may have petiole rot.  Petiole rot is a serious disease of hosta.  It is caused by the fungus Sclerotium rolfsii var. delphinii.  (Petiole rot can also affect daylily, peony, phlox, columbine, and other...

Question:
When should I harvest cauliflower?
Answer:

Cauliflower should be harvested when the heads are smooth, firm, and compact.  Full-sized heads may be 6 to 8 inches across.  Overmature heads will begin to open up and become “ricey.”  Cauliflower may be placed in perforated...

Question:
A yellow, foam-like growth has suddenly appeared in my mulched perennial bed. What is it and will it harm my plants?
Answer:

The growth in your perennial bed is probably a slime mold. Slime molds are types of fungi. Slime molds feed on bacteria and other organisms in the mulch. They do not harm plants.

Slime molds are usually a temporary nuisance. Within a few...

Question:
When is the best time to plant rutabagas in Iowa?
Answer:

The rutabaga performs best when planted in summer for a fall crop.  Sow seed at a depth of 1/4 to ½ inch from June 15 to July 15 in Iowa.  Rows should be spaced 18 to 24 inches apart.  Thin the planting within a few weeks of...

Question:
When would be the best time to prune potentillas?
Answer:

Summer-flowering shrubs, such as potentilla and Japanese spirea, bloom in summer on the current year’s growth.  Prune summer-flowering shrubs in late winter or early spring (March or early April in Iowa).

Question:
Is a tomato a fruit or a vegetable?
Answer:

There are different ways to classify or categorize plants and plant structures.  Botanically, the typical plant has roots, stems, leaves, flowers, and fruit.  The root is the edible portion of carrots, radishes, beets, and parsnips....

Question:
My 'Sunburst' honey locust is not growing well. What could be the problem?
Answer:

The ‘Sunburst’ honeylocust has distinctive yellow-green foliage.  Unfortunately, it is not a vigorous tree.  It grows slowly and is susceptible to cankers and mimosa webworms.

Cankers, caused by fungal pathogens, are localized...

Question:
What is thatch?
Answer:

Thatch is the layer of dead and living plant material that forms between the soil surface and green vegetation.  It is composed of shoots, crowns, and roots.  Thatch, to some degree, is present in all lawns.  However, when thatch...

Question:
Is it a good practice to apply salt to an asparagus planting?
Answer:

In the past, some gardeners used salt to control weeds in their asparagus plantings.  However, salt is not effective in controlling many weeds, especially grasses.  Plus, continued use of salt over several years may result in high salt...

Question:
How can I control blackspot on my roses?
Answer:

Blackspot is a common fungal disease of roses.  Symptoms of blackspot are circular black spots on the leaves.  Infected leaves turn yellow and drop prematurely.  Initially, symptoms develop on the lower leaves and gradually move...

Question:
Are black raspberries hardy in northern Iowa?
Answer:

Red and purple raspberries are hardy throughout the state.  Black raspberries, however, often suffer severe winter damage in northern Iowa and can be reliably grown only in central and southern portions of the state.  ‘Black Hawk’ (an...

Question:
My bearded irises are no longer blooming well. Why?
Answer:

The bearded irises may need to be divided.  Bearded irises should be divided every 3 to 5 years as the plants quickly become overcrowded and don’t bloom well.  July or August is the best time to dig, divide, and transplant bearded...

Question:
When should I harvest broccoli?
Answer:

Broccoli should be harvested when the head is fully developed, but before the flower buds begin to turn yellow and open.  At harvest, the terminal head should be tight, blue-green, and approximately 6 to 7 inches in diameter.  Most...

Question:
When should I cut gladiolus flowers for indoor use?
Answer:

Gladiolus for decorative indoor use should be cut as soon as the bottom flower on the spike has opened.  Most of the remaining blooms will open when the spike is brought indoors and placed in water.  When cutting gladiolus flowers,...

Question:
When should I harvest my summer squash?
Answer:

Harvest zucchini and other long-fruited summer squash varieties when the fruit are 1½ to 2 inches in diameter and 6 to 8 inches long.  Scalloped types are best when 3 to 5 inches in diameter.  Fruit should have soft skins (rinds) that...

Question:
How do you propagate forsythias?
Answer:

The forsythia is easily propagated from softwood cuttings. Softwood cuttings should be made from the current season’s growth in late June or early July. Using a sharp knife, cut off 4 to 6 inch long shoots. Pinch off the leaves on the lower half...

Pages