Ask the gardening expert



Master Gardener Coordinator Erika Johnson answers one of the questions that was asked during the Clark County Fair:

A gentleman approached the answer clinic booth at the Clark County Fair, asking when he should cut the flowers off of his onions. If you had been the master gardener working at the fair that day, what might you have told the visitor?

The volunteers at the booth did not know! But did they despair? Not a chance; they coolly pulled out the netbook provided at the booth and began a search with the terms “onion”, “flower” and “university.” Up came a Texas A&M Extension Service website with all kinds of interesting information on the growing of onions. Turns out, flowering of onions can be caused by several things, usually temperature fluctuation. An onion is classed as a biennial, which means it usually takes two years to go from seed to seed. However, early flowering may be triggered by temperatures. If an onion plant is exposed to alternating cold and warm temperatures resulting in the onion plant going dormant, resuming growth, going dormant and then resuming growth again, the onion bulbs prematurely flower or bolt. Flowering can be controlled by planting the right variety at the right time.

The onion bulbs of a flowering plant will still be edible but probably smaller. Use these onions as soon as possible because the green flower stalk which emerges through the center of the bulb will make storage almost impossible.

I would like to plant some iris that was given to me. I do not know what type it is. I know it is not bearded iris. From the description in one of your other questions (thin long leaves with beautiful purple, small and delicate-looking flowers), it might be Dutch iris. Do they need shade or can they tolerate full sun?

Iris grow best in full sun. Most iris will tolerate light shade, but they flower most freely in full sun. Dutch iris grow from bulbs, while Japanese and Siberian (and bearded) iris grow from rhizomes (fleshy underground roots). Perhaps this will help you distinguish what type you have.

Reminder; Dutch iris bulbs should be planted about 4 inches deep, and 3 to 4 inches apart in autumn.

Last year was my first year trying to grow corn. The plants looked fine, but the corn itself was bad; I had to throw away nearly all the ears as they had some awful worm thing in the top. I never tried to open an ear because of the worms. I don’t think I’ve seen any so far this summer. How do I make sure I don’t have the heartbreaking job of throwing out all my corn out again this year?

I too hate to hear you felt the need to disregard all the ears of corn last year. That pesky worm was mostly set in the top of the ear and that bad area can be easily cut off. The rest of the corn is fine in most cases.

I went to the Web to set your mind at ease. Some great info can be found on WSU Hortsense. This site was created to aid master gardeners and the general public in a wide range of information regarding ornamentals — nearly all fruiting plants and vegetables. The address is

This is what the site has to say about corn earworm: The corn earworm is the caterpillar of a light to dark brown moth with a 11/2 inch wingspan. The caterpillars are up to 11/2 inches long at maturity. They vary widely in color, but typically have darker stripes along a cream-colored to greenish body. The first generation may feed on the center shoots of the corn, attacking the tender new leaves. Later generations may feed on the silks, preventing pollination. They may also feed on the ear itself, damaging kernels and leaving behind dirty-looking droppings. The droppings may be visible at the tip of the ear. Several generations may occur in one season, as the corn earworm can progress from egg to adult moth in as little as one month during favorable conditions. Corn earworm pupae overwinter in the soil. Peppers, tomatoes, beans and many other plants are also attacked.

“Early-season plantings (before April) are less likely to be damaged.

“Encourage natural enemies such as green lacewings, parasitic wasps and other predators.

“In small plantings, a clothespin placed at the point where the silk enters the ear can prevent earworm access. Place clothespins soon after the first silk is seen.

“Plow or dig up corn plots in the fall to kill overwintering pupae and prevent emergence of adults in the spring.

“Varieties with tight husks (such as ‘Country Gentleman,’ ‘Golden Security,’ ‘Silvergent’ and ‘Staygold’) are more resistant to damage.”

These are varieties I am unfamiliar with so can’t give advice; check with the Master Gardener Office. They can offer current and highly rated varieties for Southwest Washington. Call 360-397-6060, ext. 5711, or email

Celeste Lindsay is a WSU-certified master gardener. Send questions to