Frequently Asked Questions

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 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:
How often should I water plants in hanging baskets?
Answer:

Plants in hanging baskets need to be watered frequently (especially in summer).  Potting mixes are light, well-drained, and dry out quickly.  Plus, hanging baskets may contain several plants.  In general, water plants in hanging...

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:
Can the butterfly weed be divided?
Answer:

The butterfly weed (Asclepias tuberosa) is a member of the milkweed family.  Plants grow 2 to 3 feet tall and produce flat-topped clusters of bright orange flowers from July through September.  Their flowers attract several...

Question:
When should I harvest sweet corn?
Answer:

Sweet corn should be harvested at the milk stage.  At this stage, the silks are brown and dry at the ear tip.  When punctured with a thumbnail, the soft kernels produce a milky juice.  Over-mature sweet corn is tough and doughy....

Question:
How do I care for a grapefruit tree?
Answer:

Grapefruit and several other types of citrus can be grown indoors in Iowa.  Indoors, place citrus plants in a sunny south or west window.  Water plants regularly when growing in spring and summer, less often in winter.  In spring...

Question:
How do I control weeds in my garden?
Answer:

Herbicides can be used to supplement cultivation, hand pulling, and mulches. 

Hand Pulling

Cultivation, hand pulling, and mulches are the primary means to control weeds in the home garden. 

Cultivation and hand...

Question:
My magnolia is infested with magnolia scale. What are my control options?
Answer:

Magnolia scale is the largest scale insect in Iowa.  Sap feeding by the scales causes stress to heavily infested plants and can result in stunted growth, yellowish foliage, branch dieback, or death of the plant.  Magnolia scales produce...

Question:
What is the proper way to aerate a lawn?
Answer:

Aerate lawns with a core aerator.  Core aerators have hollow metal tubes or tines that remove plugs of soil.  Avoid spike-type devices that simply punch holes (compacting the soil) in the ground.  Core aerators are often available...

Question:
I have wort-like growths on the undersides of my grape leaves. What is it and does it need to be controlled?
Answer:

The wort-like growths on the grape leaves were probably caused by the grape phylloxera.  The grape phylloxera is a small, aphid-like insect.  The grape phylloxera has a complex life cycle that affects the leaves and roots of the...

Question:
There are several large surface roots around my shade tree. Can I safely cover these roots with soil?
Answer:

Trees have shallow roots. The vast majority of a tree’s roots are located in the top 12 to 18 inches of soil.  As the tree roots grow, some of the larger roots near the soil surface may emerge from the ground. While many individuals regard...

Question:
Large areas of my lawn have turned orange. Why?
Answer:

The orange color is likely due to rust.  Rust is a fungal disease.  It can be diagnosed by walking across the lawn in white shoes.  As you walk across the lawn, bright orange spores of the rust fungus will rub off onto the shoes,...

Question:
I have some small, purplish spots on the canes of my black raspberries. What is it and how can it be controlled?
Answer:

The small, purplish spots are most likely due to anthracnose.  Anthracnose is a serious fungal disease of raspberries, especially black raspberries.  The disease is readily recognized by the small, purplish spots that develop on young...

Question:
How frequently should I water annuals in containers?
Answer:

The frequency of watering may vary considerably from container to container.  Watering frequency depends on the size and type of container, composition of the potting mix, plant species, and weather conditions.  Some plants, such as...

Question:
How do I know when a watermelon is ready to harvest?
Answer:

Harvest watermelons when the underside or belly of the fruit turns from a greenish white to buttery yellow or cream.  This color change is especially pronounced on the dark green skinned varieties.  In addition, the fruit tends to lose...

Question:
The foliage on my bleeding heart dies back in early summer. What is wrong?
Answer:

The common bleeding heart (Dicentra spectabilis) typically dies back in mid-summer in Iowa.  However, plants may die back in late spring or early summer if growing conditions are not favorable.  The common bleeding heart...

Question:
My tomatoes are developing white or yellow areas on the sides of the fruit exposed to the sun. Why?
Answer:

The white or yellow areas on your tomatoes are due to sunscald.  Sunscald occurs on fruit exposed to the sun during periods of extreme heat.  Initial symptoms of sunscald are the development of shiny white or yellow areas on the fruit....

Question:
How long does it take a compost pile to break down?
Answer:

The rate of decomposition depends upon the composition of the compost pile, level of management, and other factors. A well-managed compost pile (one that is watered and turned regularly) containing a mixture of shredded plant material should be...

Question:
There are tan-colored, rough spots on the surface of my pear fruit. Is it possible to prevent this from occurring?
Answer:

Russeting is probably responsible for the tan-colored spots on your pears.  Russeting also develops on the surface of apples.  While affected fruit are not attractive, russeting doesn’t affect the eating quality of the fruit. ...

Question:
There is a pile of sawdust-like material at the base of a large tree. What could be the problem?
Answer:

It’s likely the pile of sawdust-like material was produced by carpenter ants.  Carpenter ants commonly nest inside older, hollow trees or in trees with dead limbs or branches.  Carpenter ants do not eat wood.  However, they...

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:
When should grapes be harvested?
Answer:

Grapes should not be harvested until fully ripe.  The best indicators of ripeness are color, size, and flavor. 

Depending on the variety, the berry color changes from green to blue, red, or white as the grapes approach maturity....

Question:
I have a chokecherry that sends up suckers in the yard around it. Is there any way to stop it from suckering?
Answer:

Chokecherries (Prunus virginiana) and several other trees will send up shoots (suckers) from their roots.  Unfortunately, there is nothing the home gardener can do to prevent these trees from suckering. 

The best way to...

Question:
When is the best time to sow grass seed?
Answer:

Late summer (mid-August to mid-September) is the best time to establish a lawn from seed in Iowa.  Late summer seeding has several advantages over spring seeding.  The seeds of cool-season grasses germinate quickly in the warm soil of...

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