Frequently Asked Questions

Question:
I've been told that tiger lilies should not be planted near Asiatic lilies. Is this true?
Answer:

Many lily enthusiasts don’t grow tiger lilies (Lilium tigrinum) because they are often infected with lily mosaic virus.  Lily mosaic virus causes little harm to tiger lilies.  Oftentimes, you can’t tell that they have the...

Question:
The grass beneath one of my trees has turned brownish orange. Why?
Answer:

Greenbug aphids may be responsible for the brownish orange color of the turfgrass.  Greenbug aphids feed only on plants of the grass family (Kentucky bluegrass, corn, sorghum, etc.).  Greenbugs live on the grass blades and feed on sap...

Question:
How do gynoecious cucumber varieties differ from other varieties?
Answer:

Cucumbers and other vine crops are monoecious.  Monoecious plants have separate male and female flowers on the same plant.  Male and female flowers are similar in appearance.  However, the female flowers have small, immature fruits...

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 can I plant impatiens outdoors?
Answer:

Plant impatiens outdoors after the danger of frost is past.  It’s usually safe to begin planting impatiens in late April in southern Iowa and mid-May in northern portions of the state.  Plants purchased at a greenhouse or started...

Question:
Are ornamental sweet potatoes edible?
Answer:

Ornamental sweet potatoes and sweet potatoes grown in the vegetable garden are different varieties of Ipomoea batatas.  The ornamental varieties are grown for their attractive foliage, while those in the vegetable garden are grown for their...

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 are the site requirements for bee balms?
Answer:

Bee balms (Monarda species) perform best in full sun.  The planting site should receive at least 6 hours of direct sun per day.  Plants grown in partial shade won’t flower as heavily and are more susceptible to powdery mildew....

Question:
Are white fruited pumpkins edible?
Answer:

White fruited pumpkins are edible.  White fruited varieties, such as ‘Lumina,’ have a white skin and orange flesh.  They are chiefly grown for their unique “ghostly” appearance.  However, the orange flesh is suitable for cooking....

Question:
The leaves on my cherry tree have small holes in them and are turning yellow. What is the problem?
Answer:

Cherry leaf spot is probably responsible for the symptoms on your cherry tree.  Cherry leaf spot is caused by the fungus Blumeriella jaapii.  The fungus produces small purple spots on the upper surface of the leaves. ...

Question:
What are the orange-colored growths on the leaves of my ash tree? Is control necessary?
Answer:

Ash rust is probably responsible for the orange growths on your ash tree.  Ash rust is caused by the fungus Puccinia sparganioides.  The fungus produces conspicuous swellings on leaves, petioles, and twigs.  Infected...

Question:
Flower buds form on my peonies, but don't open. Why?
Answer:

There are several possible explanations why peony buds fail to open. 

Not Receiving Enough Sunlight

Peonies bloom best in full sun.  In partial to heavy shade, plants are weak and may not be able to supply adequate food...

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

There are different ways to classify or categorize plants and plant structures.  We eat many plant parts including roots, stems, leaves, flowers, seeds, and fruit.  The root is the edible portion of carrots, radishes, beets, and...

Question:
What causes my peaches to rot and turn brown?
Answer:

Brown rot is a common fungal disease of peaches and other stone fruits.  Affected fruits develop circular light brown spots that expand rapidly and rot the fruit.  Sometimes the fungus that causes this rot is visible as ash-gray tufts....

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:
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:
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:
Some of my strawberries in the garden are covered with a gray, velvety growth. What is it and how can it be controlled?
Answer:

The gray, velvety growth on your berries may be gray mold.  It is also known as Botrytis fruit rot.  Gray mold is favored by poor air circulation and a high humidity in the strawberry planting.  The most commonly infected berries...

Question:
What are Martagon lilies?
Answer:

The Martagon lily (Lilium martagon) is one of the most widely distributed lilies in the world.  It grows naturally in most of Europe and parts of Asia.  It is also referred to as Turk’s cap lily. 

The Martagon lily...

Question:
Areas of my lawn that were covered with snow for most of the winter aren't greening up. What could be wrong?
Answer:

Snow molds may be responsible for the brown spots in your lawn.  Two snow mold diseases, gray snow mold and pink snow mold, occur in Iowa.  Gray snow mold is caused by two species of the fungus Typhula, while pink snow mold is...

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

Numerous eggplant varieties (cultivars) are available for the home garden.  These varieties differ in color, size, and shape.  Fruit colors include green, white, pink, purple, and black.  Some fruit are striped.  Fruit may be...

Question:
What is the proper way to plant a balled and burlapped tree?
Answer:

Dig a hole that is 2 to 3 times wider than the diameter of the tree’s rootball.  The depth of the hole should be 2 or 3 inches less than the height of the rootball.  Slope the sides of the hole so the top of the hole is several inches...

Question:
What are the cultural requirements for New Guinea impatiens?
Answer:

New Guinea impatiens perform best in locations that receive morning sun and afternoon shade.  Eastern exposures are often best.  Plants that receive too much sun don’t bloom well (flowers are smaller and fewer in number) and may have...

Question:
Freezing temperatures in May damaged my potato plants. Will I need to replant?
Answer:

Potato shoots (stems) are sensitive to freezing temperatures.  Symptoms of freeze damage may vary from blackening of the leaf margins (minor damage) to death of all aboveground growth (severe damage).  Fortunately, severely damaged...

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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