Frequently Asked Questions

Question:
In regards to tree fruits, what is meant by the term self-unfruitful?
Answer:

Pollination is the transfer of pollen from the anther to the stigma.  After pollination and fertilization, fruit set occurs.  There are two types of pollination.  Self-pollination occurs when the pollen is transferred from the...

Question:
Will a crabapple pollinate a nearby apple tree?
Answer:

A crabapple is a type of apple.  The main difference between an apple and a crabapple is the size of the fruit.  A crabapple is a tree that produces fruit that are less than 2 inches in diameter.  An apple tree produces fruit that...

Question:
Why isn’t my apple tree bearing fruit?
Answer:

The lack of fruit is likely due to the absence of flowers, poor pollination, or low temperatures during bloom.  

The lack of flowers is often due to the age of the tree.  After planting, most dwarf and semi-dwarf apple trees don’...

Question:
How do I care for a jade plant?
Answer:

Place the jade plant (Crassula argentea) in a sunny window where it receives at least 4 hours of direct sunlight.  The jade plant is a succulent which stores water in its foliage and stems.  Overwatering (watering too...

Question:
How do I care for an umbrella tree?
Answer:

The umbrella tree (Schefflera actinophylla) is native to rainforests in Australia and New Guinea.  In the home, place the umbrella tree in bright, indirect light near an east, west, or south window.  Allow the potting soil to...

Question:
The central portions of several of my ornamental grasses are dead. Why?
Answer:

The centers of ornamental grasses often die as the plants get older.  When this occurs, it’s a good time to dig and divide the grasses.  When the grasses begin to grow in spring, dig up entire clumps, cut out and discard the dead center...

Question:
My tulips are no longer blooming. Why?
Answer:

Most modern tulip cultivars bloom well for 3 to 5 years.  Tulip bulbs decline in vigor rather quickly.  Weak bulbs produce large, floppy leaves, but no flowers.  

To maximize the number of years tulips are in bloom, choose...

Question:
Which native ferns are suitable for the home landscape?
Answer:

Native ferns that are good additions to shady locations in the home landscape include the northern maidenhair fern (Adiantum pedatum), lady fern (Athyrium filix-femina), intermediate wood fern (Dryopteris intermedia),...

Question:
Which native shrubs can be grown in shady locations in the home landscape?
Answer:

Native deciduous shrubs that can be successfully grown in partial shade include serviceberry (Amelanchier arborea), pagoda dogwood (Cornus alternifolia),  gray dogwood (Cornus racemosa), bush honeysuckle (...

Question:
When can I remove daffodil foliage?
Answer:

Daffodil foliage should not be removed until it has turned brown and died.  The length of time it takes the foliage to die back depends on bulb type, weather, and other factors.  The foliage of daffodils usually doesn’t die back until...

Question:
When can I move daffodil bulbs?
Answer:

Daffodils can be dug up and replanted as soon as the foliage dies back (turns brown) in early summer.  Daffodils can also be dug up and replanted in fall (October).  If you would like to move daffodil bulbs in fall, mark the site when...

Question:
Should I tie or braid the daffodil leaves after the daffodils are done blooming?
Answer:

After flowering, daffodil foliage typically persists for 4 to 6 weeks.  Daffodil foliage tends to get floppy and look a little unruly.  However, it’s best to leave the foliage alone and not tie or braid the leaves.  The daffodil...

Question:
Why is my sycamore tree dropping its leaves?
Answer:

The leaf drop is likely due to anthracnose. Anthracnose is a common fungal disease of sycamore, ash, maple, oak, and other trees. Anthracnose is most severe in years with cool, wet spring weather. While anthracnose may cause extensive defoliation...

Question:
Last summer the leaves on my peach tree were puckered and reddish in color. What was the problem?
Answer:

The symptoms are those of peach leaf curl.  Peach leaf curl is a fungal disease.  The disease is caused by the fungus Taphrina deformans.  Infections occur as the peach tree buds begin to swell in spring. 

A...

Question:
My rhubarb plants are blooming. What should I do?
Answer:

The flower stalks should be promptly pulled and discarded.  Plant vigor and next year’s production will be reduced if the plants are allowed to flower and set seed. 

Flower formation may have been induced by stressful growing...

Question:
When can I start harvesting newly planted rhubarb?
Answer:

After planting rhubarb, it’s best to wait 2 years (growing seasons) before harvesting any stalks.  The two year establishment period allows the plants to become strong and productive. 

Rhubarb can be harvested over a 4 week...

Question:
When should I stop harvesting rhubarb?
Answer:

Gardeners should stop harvesting well established rhubarb plants in mid-June in Iowa.  Continued harvest through the summer months weakens the rhubarb plants and reduces the yield and quality of next year’s crop.  

Question:
Can I harvest rhubarb in summer?
Answer:

If the rhubarb plants are vigorous, pulling a few stalks and preparing a dish for a special occasion in summer shouldn’t be a problem.  Harvesting rhubarb in summer should be a one time event, not a frequent practice.  Continued harvest...

Question:
Why is my rhubarb flowering?
Answer:

Flower development is natural for rhubarb and most other plants.  Drought, extreme heat, and infertile soils may encourage flowering.  Age is another factor.  Old plants tend to flower more than younger ones. 

...

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

The bearded irises may need to be divided.  Bearded irises should be divided every 3 to 5 years as the plants quickly become overcrowded and don’t bloom well.  July or August is the best time to dig, divide, and transplant bearded...

Question:
How do you care for bearded irises after they are done blooming?
Answer:

As soon as bearded irises are done blooming, remove the spent flowers.  Removal of the spent flowers improves the appearance of the plants and prevents seed pod formation.  Bearded irises require little care during the summer months....

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:
My peonies bloom poorly. What could be wrong?
Answer:

There are several factors which may cause peonies to bloom poorly.  Peonies perform best in areas that receive at least 6 hours of direct sun each day.  Peonies that receive less than 4 hours of direct sun will not bloom well. ...

Question:
What are some good native perennials for a shady site?
Answer:

When selecting plants for the shade garden, one group of plants that is often overlooked are native woodland wildflowers.  Since they are native to the state, woodland wildflowers are well adapted to the area.  They are easy to grow and...

Question:
What are some good groundcovers for shade?
Answer:

Excellent groundcovers for shade include bugleweed (Ajuga spp.), wild ginger (Asarum canadense and A. europaeum), barrenwort (Epimedium spp.), sweet woodruff (Galium odoratum), hosta (Hosta...

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