Frequently Asked Questions

Question:
Some of the leaves in my river birch are turning yellow and dropping to the ground. Why?
Answer:

Hot, dry weather may be responsible for the leaf drop on the river birch. River birches shed some of their leaves in hot, dry weather.  Leaves in the interior of the river birch turn yellow and drop to the ground.  Healthy, well-...

Question:
How do I control water grass in my lawn?
Answer:

“Water grass” is an ambiguous name.  Several plants are occasionally referred to as water grass.  Two common lawn weeds that are sometimes referred to as “water grass” are crabgrass and yellow nutsedge. 

Crabgrass

...

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:
Are marigolds pest free?
Answer:

While marigolds are seldom bothered by insects and diseases, they are not problem free.  Spider mites can devastate marigolds in hot, dry weather.  Grasshoppers can also cause considerable damage.  Aster yellows is an occasional...

Question:
When should I plant Chinese cabbage?
Answer:

Chinese cabbage performs best when planted in summer for a fall crop.  (Chinese cabbage frequently goes to seed when planted in spring.)  Sow the seed of Chinese cabbage at a depth of 1/4 to ½ inch in July.  Rows should be spaced 2...

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:
Are there special corn varieties that are grown to produce "baby" corn?
Answer:

The small size of “baby” corn suggests that it’s a special variety.  However, most baby corn is actually grown from regular sweet and field corn varieties.  The ears are harvested when they are 2 to 4 inches long and 1/3 to ½ inch in...

Question:
What would be a good planting site for the magic lily?
Answer:

The magic lily (Lycoris squamigera) is a rather intriguing plant.  Other common names include resurrection lily, surprise lily, hardy amaryllis, and naked lady.  The life cycle of Lycoris squamigera is different from...

Question:
What is the proper way to harvest and store popcorn?
Answer:

The moisture content of popcorn determines its popping quality.  The ideal moisture content of popcorn is 13 to 14.5 percent. 

Popcorn should be left on the stalk until fully mature.  Harvest the ears when the husks are...

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 should I water a newly seeded lawn?
Answer:

After seeding, keep the upper 1 inch of soil moist by watering once or twice a day.  With adequate moisture and warm soil temperatures (55 degrees Fahrenheit or above), the seeds of most turfgrasses should germinate in 2 to 3 weeks....

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:
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:
How can I avoid drift problems when applying a broadleaf herbicide to my lawn?
Answer:

Before applying any herbicide, carefully read and follow label directions.  When applying liquid formulations, potential spray drift problems can be avoided by following simple precautions.   Don’t spray when winds exceed 5 mph....

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:
Can I keep rabbits out of my vegetable garden by planting marigolds around the perimeter?
Answer:

Marigolds do not repel rabbits, deer, or other animals.  In fact, rabbits occasionally browse heavily on marigolds.  Erecting a chicken wire or hardware cloth fence around the vegetable garden is the best way to keep rabbits out of the...

Question:
When should I harvest cucumbers?
Answer:

Harvest cucumbers every 2 to 3 days and promptly pick the fruits when they reach the desired size.  Pickling varieties should be harvested when the fruits are 2 to 4 inches long.  Slicing cucumbers should be 6 to 8 inches long and 1.5...

Question:
How can I control powdery mildew on my garden phlox?
Answer:

Powdery mildew is a common disease of garden phlox (Phlox paniculata).  The fungal disease produces a grayish white coating on the leaves.  Infected leaves eventually turn yellow and then brown.  Initial symptoms appear on...

Question:
The ears on my sweet corn are poorly filled. What are possible causes?
Answer:

Poorly filled ears are usually the result of poor pollination.  Hot, dry winds and dry soil conditions may adversely affect pollination and fertilization and result in poorly filled ears. Water sweet corn during pollination if the soil is...

Question:
Can I plant my Easter lily outdoors after it is done blooming?
Answer:

Individuals wishing to save their Easter lily (Lilium longiflorum) should place the plant in a sunny window after flowering.  Continue to water the plant when needed.  Fertilize once every 2 weeks with a dilute fertilizer...

Question:
Can I place weeds and diseased plant debris from the vegetable garden in the compost pile?
Answer:

It would be best to place weeds that are producing seeds and diseased plant debris in biodegradable bags and have the material picked up and composed by a municipal or commercial composting facility.  The temperatures in home compost piles...

Question:
The foliage at the ends of the branches on my honey locust are turning brown. Why?
Answer:

The browning of the honey locust foliage is probably due to the mimosa webworm.  Damage occurs when the caterpillars tie honey locust leaflets together and feed on the foliage inside the tightly compressed, protective webs.  Affected...

Question:
How should I water a newly sodded lawn?
Answer:

A newly sodded lawn should be watered once or twice a day for the first 7 to 10 days.  Apply enough water to moisten the sod and upper 1 inch of soil.  The sod should root to the soil in about 10 days.  At this point, gradually...

Question:
What are jostaberries?
Answer:

Jostaberries are a cross between black currants and gooseberries.  Plants are vigorous and may grow to a height of 6 to 8 feet.  Jostaberry fruit are similar in size to gooseberries and black in color.  Plants possess excellent...

Question:
The inner growth in my arborvitae is turning brown. Is this a problem?
Answer:

The browning of the inner foliage is probably due to seasonal needle drop. It’s normal for evergreens (pine, spruce, fir, juniper, arborvitae, etc.) to shed their oldest (innermost) needles in fall. The innermost needles gradually turn yellow or...

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