Do I need to divide the perennials in my garden? 
Some perennials, such as garden peonies, can be left undisturbed for 50 or more years. Others need to be divided periodically to contain their spread or to rejuvenate declining plants.  Perennials, such as gooseneck loosestrife (Lysimachia clethroides), obedient plant (Physostegia virginiana) and bee balm (Monarda didyma) are vigorous growers. They grow so rapidly that they begin to crowd out neighboring plants within a few years. Gooseneck loosestrife and other vigorous growers should be divided every two to three years.

After dividing the perennials, replant some of the divisions, give others to relatives or neighbors and discard any remaining plants in the compost pile. In contrast, the performance of some perennials, such as bearded iris (Iris hybrids), begins to decline after a number of years. If not divided every three to five years, bearded irises usually don’t bloom well because of overcrowding. Declining perennials should be divided to rejuvenate the plants. 

When should I prune my hybrid tea roses? 
The upper portions of modern roses, such as hybrid teas, floribundas and grandifloras, typically winterkill due to exposure to low winter temperatures and extreme temperature changes.  Gardeners should prune out the dead wood after the winter protection is removed from modern roses in late March to mid-April. 

When can I start cannas indoors? 
Start canna rhizomes indoors four to six weeks before the average last frost date in your area. Plant the cannas in large pots. The rhizomes should be covered with 3 to 4 inches of potting soil. 

Should I fertilize my fruit trees? 
It is generally not necessary to fertilize fruit trees in Iowa. Most Iowa soils can supply sufficient amounts of nutrients to fruit trees. Check tree growth to determine whether fruit trees need fertilization. Young, nonbearing fruit trees should grow approximately 15 to 30 inches per year.  Bearing trees should produce 8 to 15 inches of new growth. (The actual amount of new growth will vary due to differences in varietal vigor.)  Fruit trees making less than desirable growth may need fertilization. Apply a balanced fertilizer, such as a 10-10-10, in early spring before bud break.  The recommended rate is 1/10 pound of actual nitrogen per year of tree age.  (Tree age is the number of years since the tree was planted in the home garden.) 
 
For example, a 5-year-old tree should receive 5/10 or a half pound of nitrogen. Uniformly broadcast 5 pounds of the 10-10-10 fertilizer (10 percent of 5 is a half pound of N) in a circular band beginning about 2 feet from the trunk and extending out slightly beyond the dripline of the tree. One pound of actual nitrogen is the maximum for fruit trees 10 years of age and older. 
 
If the lawn in the vicinity of the fruit trees is fertilized on a regular basis, there should be no need to fertilize the trees. The fruit tree roots will absorb nutrients from the lawn fertilizer. Additional fertilizer will probably be excessive. Over-fertilization may actually reduce crop yields. 

-30-