Frequently Asked Questions

Question:
How long should I continue to water a newly planted tree?
Answer:

The roots of trees continue to grow until the ground freezes.  If the weather is dry, continue to water newly planted trees until the soil freezes in winter.  Small trees usually require watering for 1 or 2 growing seasons.  It may...

Question:
A blackish spot develops on the bottom of my tomato fruit. What is the problem and how can it be prevented?
Answer:

Blossom end rot is probably responsible for the blackish spots on the tomato fruit.  Blossom end rot is a common problem on tomatoes.  It appears as a brownish black spot on the blossom end (bottom) of the fruit.  Secondary...

Question:
How can I determine if my oak tree has oak wilt?
Answer:

Oak wilt is a serious disease that can infect many oak species.  It is caused by the fungus B. fagacearum.  Red and pin oaks are very susceptible to the oak wilt fungus and can die within 4 to 6 weeks.  White and bur oaks...

Question:
How often should I aerate a lawn?
Answer:

The frequency of aeration is largely determined by the soil type and the amount of use.  Lawns growing in heavy, clay soils and those subject to heavy foot or pet traffic should be aerated twice a year.  Once a year should be sufficient...

Question:
When should I harvest sour cherries?
Answer:

Sour or pie cherries should be harvested when the fruit are full-flavored, somewhat soft, and juicy.  (Cherries picked before they are mature will not ripen off the tree.)  For immediate use, the cherries can be picked without the stems...

Question:
There are several bands of holes around the trunk of my pine tree. Is the tree infested with borers?
Answer:

The holes were likely created by sapsuckers.  Sapsuckers, members of the woodpecker family, damage trees by drilling holes in the trunk or large branches.  Sapsucker damage is very distinctive.  They drill uniform, 1/4 inch holes...

Question:
What is the proper way to deadhead roses?
Answer:

Deadheading or the removal of faded flowers is done to encourage additional bloom on hybrid tea and other repeat-flowering roses.  Hybrid tea roses usually have one or two 3-leaflet leaves immediately below the flower.  Next (lower down...

Question:
We recently moved into a home that has a large red raspberry planting in the backyard. How should we rejuvenate the planting?
Answer:

Red raspberries sucker freely.  If not confined, plants will spread rapidly.  Red raspberries are most productive when grown in 2-foot-wide hedgerows.  If the raspberry planting is several feet wide, plant rows need to be...

Question:
My chrysanthemums get tall and lanky and flop over onto the ground in fall. What can be done to prevent this?
Answer:

Pinch newly planted and established mums from spring to mid-summer.  Remove the upper 1 to 2 inches of the shoots when the stems are 6 to 8 inches tall.  New lateral (side) shoots will develop along the stems.  Pinch again when the...

Question:
Do I need to treat my peas with an inoculant before planting?
Answer:

Peas are members of the legume (Fabaceae) family.  Through a symbiotic relationship with a soil bacterium (Rhizobium), peas are able to “fix” atmospheric nitrogen in nodules on their roots. 

Peas will grow and produce a crop...

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:
Can hollies be successfully grown in Iowa?
Answer:

American holly (Ilex opaca) and English holly (Ilex aquifolium) are prized for their glossy, green leaves and brightly colored fruit. Sprigs of both hollies are often used in wreaths, centerpieces, and other Christmas...

Question:
How often should I fertilize hybrid tea roses?
Answer:

To encourage vigorous growth and abundant bloom, hybrid tea, floribunda, and grandiflora roses should be fertilized two or three times a year.  Fertilizer applications can be made in early spring (immediately after pruning), during the first...

Question:
What are the proper pruning procedures for purple raspberries?
Answer:

Proper pruning of purple raspberries promotes high yields, helps control diseases, and facilitates harvesting and other maintenance chores. 

In March or early April, remove all small, weak canes, leaving only 4 or 5 of the largest,...

Question:
How often should I pinch my mums?
Answer:

Pinch chrysanthemums 2 to 3 times from spring to mid-summer.  Remove the stem tips when the shoots are 6 to 8 inches tall.  New lateral shoots will develop along the stems.  Pinch again when these new shoots reach a length of 6 to...

Question:
I planted some lima beans this spring, but the plants produced only a few pods. Why?
Answer:

In the midwest, yield is largely determined by weather conditions.  Lima beans grow best when temperatures are between 70 and 80 degrees Fahrenheit.  They also require 1 inch of water per week (either from rain or irrigation) during...

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).

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