Fall, early spring best time to fertilize trees

Q. Is it too late to fertilize evergreens like yews and arborvitae? How about perennials (I have a lot of different kinds)?

A. Yes. Stop fertilizing perennials, trees and shrubs by Aug. 1. Late-summer fertilization can stimulate late-season growth that is more susceptible to winter injury.

For the greatest benefit, fertilize trees in fall after they go dormant or in early spring before growth begins. Spread an inch or two of compost over the soil surface around perennials every other year. This is often sufficient for most perennials. Supplement this with a low nitrogen slow release fertilizer in spring as needed.

Q. My gladioli plants are done blooming. Do I dig them up?

A. Allow your gladioli plants to continue to grow in the garden. As long as the leaves are green they are producing energy that will be stored in the corms, swollen underground structures, for next year. Dig corms after the first frost.

Save the corms only from healthy plants. Carefully dig, shake off excess soil and cut the tops back to 1 to 2 inches above the corm. Allow them to dry in the sun for a couple of days. Then gently remove any remaining soil and spread corms on flats or trays to cure for 2 to 3 weeks in a warm (80- to 85-degree) location. Store cured corms in open paper bags, mesh bags or paper boxes in a cool (35- to 40degree) dark location.

Q. My pattypan squash plant develops flowers and small nickel-size squash, then next day they are gone. What is eating them, and how do I stop them?

A. Ground squirrels, woodchucks and raccoons are a few of the critters that like to munch on our garden produce. They often take a bite or two and leave the rest on the plant. Because these are small and tender, they may be eating as fast as the plants are producing.

Try covering the plants with bird netting. The bees will still be able to reach the flowers, but you just might stop the critters. If you opt for repellents, make sure they are safe to use on or around food plants. Repellents are most effective when applied before the damage begins. Once the animals have found a good place to dine, it is difficult to scare them away.

Q. I have a rose of Sharon that is loaded with blooms. Do I need to prune it? If so, when?

A. Young shrubs generally need minimal pruning the first year or two. Only remove damaged, crossing and rubbing branches.

If you purchased a single-stem plant with minimal branches, you can prune it back to 2 feet to encourage lower branches to form. Make your cut above a healthy outward-facing bud.

As the shrub grows, continue to remove problem branches, including any inward-growing branches. Rose of Sharon shrubs tend to sucker. Prune out a few older stems to ground level on mature plants as needed.

Reduce the height of the plant by cutting long stems back to an outward-facing branch or above a healthy bud. Remove no more than one third of the overall plant at one time. Heavy pruning can stimulate lots of growth that will need pruning next year. Extensive pruning also results in fewer but larger flowers while light or no pruning will mean more but smaller flowers.

Prune rose of Sharon in late winter or early spring, before growth begins.