Frequently Asked Questions

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

Bearded irises should be divided every three to five years. If not divided, plants become overcrowded and flower production decreases. July or August is the best time to dig, divide, and transplant bearded irises. 

If bearded...

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:
Can I plant perennials in late summer?
Answer:

Late summer (late August to mid-September) is an excellent time to plant many perennials.  It is also a good time to move or divide perennials, such as peony, daylily, garden phlox, and oriental poppy.  Perennials planted in late summer...

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:
Can I dispose of my wood ashes in the garden?
Answer:

Wood ashes contain small amounts of several plant nutrients. The nutrient content of wood ashes depends on the type of wood burned, the thoroughness of its burning, and other factors. Generally, wood ashes contain 5 to 7 percent potash, 1 percent...

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...

Question:
What are the best storage conditions for apples?
Answer:

The temperature and relative humidity during storage are critical for maximum storage life.  Optimum storage conditions for apples are a temperature near 30 to 32 degrees Fahrenheit and a relative humidity between 90 and 95 percent. ...

Question:
What causes pine wilt?
Answer:

Pine wilt is a common disease that causes browning and death of pines, especially Scotch pine. Austrian, mugo, red, jack, and white pine may also be affected, but less commonly than Scotch pine. Affected trees turn brown and die within a few...

Question:
When mowing the lawn, what is the proper mowing height?
Answer:

Kentucky bluegrass lawns should be mowed at a height of 2½ to 3 inches in the spring and fall months.  Mow bluegrass lawns at a height of 3 to 3½ inches in June, July, and August.  A higher mowing height in summer helps to cool the...

Question:
What type of pruning equipment is needed to prune grapevines?
Answer:

Tools required to prune grapevines include a hand shears, lopping shears, and saw.  Brightly colored ribbons or cloth strips can be used to identify fruiting canes and renewal spurs.  

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

When selecting a forsythia, choose a cultivar that reliably blooms in Iowa.

Forsythias to avoid planting in Iowa

The flower buds on some varieties are not reliably cold hardy in Iowa, and typically don’t bloom well in Iowa as...

Question:
There are yellow-green bugs eating the flowers on my roses. What are they and how can they be controlled?
Answer:

The yellow-green bugs are probably the adults of the northern corn rootworm.  The larvae of the northern corn rootworm feed on the roots of corn plants.  The adults (yellow-green beetles) appear in mid-summer and are present until frost...

Question:
How do I prevent straw from blowing off my strawberry bed in winter?
Answer:

In windy, exposed areas, straw mulches can be kept in place by placing wire or plastic fencing over the area.  The fencing can be held in place with bricks or other heavy objects.

Question:
When and how do you divide bearded irises?
Answer:

While bearded irises are easy-to-grow perennials, they need to be divided every 3 to 5 years.  If not divided, plants become overcrowded and flower production decreases.  Crowded plants are also more prone to disease problems.  In...

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:
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:
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:
How do I have my garden soil tested?
Answer:

Soil testing services are provided by neighboring universities and private laboratories.  Information on how to collect good soil samples for testing and recommendations for how to find testing laboratories can be found at ...

Question:
When should I harvest my bell peppers?
Answer:

Bell peppers are usually harvested when large, firm, and dark green (immature stage).  They may also be allowed to fully ripen to red, yellow, orange, or other colors.  Fully mature bell peppers are slightly sweeter and contain higher...

Question:
Can blueberries be successfully grown in Iowa?
Answer:

Blueberries can be successfully grown in Iowa.  However, they do have special growing requirements. 

Blueberry plants require a sunny location and a well-drained soil high in organic matter.  Avoid wet, poorly drained sites...

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 mow my lawn?
Answer:

Kentucky bluegrass lawns should be mowed at the height of 2½ to 3 inches in spring and fall.  Set the mower blade to a height of 3 to 3½ inches during summer. 

As a general rule, never remove more than 1/3 of the total leaf...

Question:
Are there any peach varieties that can be successfully grown in Iowa?
Answer:

Peaches are not reliably cold hardy in most parts of Iowa.  It is possible to grow ‘Reliance’ (yellow flesh, freestone) and ‘Polly’ (white flesh, clingstone) in the southern one-third of Iowa. 

Growing peaches in Iowa is...

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:
There is a large, hard growth on the cane of one of my roses. What is it?
Answer:

The large, hard growth is probably crown gall.  Crown gall is caused by the bacterium Agrobacterium tumefaciens.  The bacterial disease can infect roses, grapes, apples, raspberries, willows, euonymus, and many other woody...

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