Ask the gardening expert



My garden was a success as a whole this year, with a few minor bobbles here and there. It seems I’m remembering that you talked about companion planting last year. I think you said you don’t believe in it. My new neighbor believes in it, swears by it, but her garden did no better than mine. So would you please reprint it?

Yes, it was in March I had a thing or two to say about companion planting. I said I’m not against it, it’s only that I haven’t seen any scientifically proven studies that prove it to be more than a nice idea. I would never argue for or against, I just saying I’ve have not seen proof one way or another.

So here’s the repeat:

My grandmother always had a huge and wonderful garden. She told me that she has great success because her family taught her to remember to plant certain plants close to one other. She called it “companion growing.” I have always wondered why people doing garden writing don’t talk about it?

You probably won’t see me advocating “companion planting,” as I have always heard it called. I have nothing against people suggesting it to one another, and I understand that families have beliefs and traditions. If it helps get their garden growing then I’m for it! Companion planting has been a popular practice for many ages. This and another age-old beliefs are still used by folks, such as planting by the phases of the moon. There are many folks around the world and down through history who believe in one or maybe even both of these practices. There is certainly no harm in their use, but also no scientific proof that they assist in the craft of growing vegetables or other plants. My own philosophy is based on horticultural studies done mostly by land grant universities, and other “in field” scientific studies. However, I’ve read that some research folks suggest that some vegetable and herb plants of the same family may not do well planted in close proximity as they may be competing for the same nutrients available in the soil. That’s just a suggestion — again, no scientific proof.

In my thinking your grandmother’s success was more than likely due to her talented garden tending and dedication, but then again who knows, maybe it worked for her.

Master Gardeners’ in-house answer clinic challenge:

Late last week a woman came into the answer clinic with a small green caterpillar in a jar. “What is this that is eating my geranium?” she asked. If you’d been in the answer clinic that day, how do you suppose you’d have responded? To see how the Master Gardener on duty responded, check the bottom of this message.

Submitted by Clark County’s newly awarded “No. 1 tree hugger” Erika Johnson, Master Gardener program coordinator.

The critter decimating the woman’s geranium was identified as the tobacco budworm (Heliothis virescens). Also called the geranium budworm, it also commonly affects petunia plants. The caterpillars usually show up in the summer, but you probably won’t spot the pests themselves. You’ll likely just see their droppings, which look like little black seeds. Budworms feed on flower buds, petals and surrounding foliage, chewing small holes in the plant tissue. Injured buds usually don’t open, and those that do look all chewed up and raggedy. Budworm pupae overwinter in warm-climate soils and have developed resistance to most insecticides licensed for residential use. Control budworm populations by handpicking, searching for the budworms around dusk since these light-shy pests typically hide during the day. Because the budworm bores inside of buds and stems, it’s difficult to control with insecticides, plus it’s resistant to many pesticides. Synthetic pyrethrins labeled for garden use are the most effective. Bacillus thuringiensis (Bt), an organic pesticide, will provide only minimal control.

Erika Johnson, our beloved Master Gardener program coordinator, has allowed me to use her answer clinic challenges each week, I so appreciate this generous gesture, since I’ve been a little laid up for several weeks, and so grateful to her.

Hope to be up to “full power” next week. Thanks Erika!

Are you seeing an increase in the number of dying and dead birch trees around your community this year? And what about mature Douglas firs turning brown and dying? What do you think is afflicting our trees? See the bottom of this message for the answer. (I noticed some pin oaks with bare tops in the grocery parking lot yesterday.)

The last few years have seen very dry summers, resulting in lack of sufficient water for many of our urban trees already subject to various stressors. This leaves them vulnerable to infestation from borers which wouldn’t kill otherwise healthy, thrifty trees. Keeping surrounding turf from competing for limited moisture and adding rich, nutritious leaf mulch a couple of times a year will go a long way in helping our trees to thrive. Watering slowly and deeply a few times throughout the summer is also helpful.

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