Garden Q&A

Question: I put petunias in this year and do not see any bees or butterflies on them and think maybe they are pollen-less. Were commercial pollen-less flowers created for people with allergies? Should I stay away from them if I want to attract beneficial insects?

- Marita Fitzpatrick-Frechette
Answer: Please do not be taken aback if your question about the birds and the bees leads to a short discussion of sexual organs. Of plants.

Pollen is the equivalent of sperm. It is borne on the stamens of a flower and, for fertilization and seed production, must get to the ovary, which is found at the base of the pistil, which has a sticky tip, the stigma, to catch pollen, which is then transmitted down to the ovary. It can get to the stigma via the air; the ripe pollen of many flowers drifts naturally. For species vigor and complete fertilization, the pollen usually needs to come from another flower or, better yet, another plant.

Bees, butterflies, other insects, and hummingbirds become the unwitting transporters of pollen from one flower to another. But they don't care one whit about the pollen, they're after nectar. So a pollen-less flower will still be visited by hungry insects.

Flowering plants come in two basic categories: monoecious and dioecious. The former have male and female flower parts on a single plant. In some cases, each flower is "complete," with male parts (stamens) and female (pistil). Others, notably the squash family, produce separate male flowers and female flowers on the same plant.

In dioecious plants, there are separate male plants and female plants; holly and ginkgo are dioecious. So right there, you have examples from nature of flowers (female) without pollen that still get visited by insects seeking nectar and depositing pollen from male flowers.

Hybridization, whether in nature or by human intervention, can produce sterile strains without pollen. "Mule marigolds" are in this category. It's nice to think sterile annuals were bred with the allergic in mind, but the real point is that without the ability to produce seed, these varieties produce almost continuous blossoms through the growing season, which is what the gardening public has come to expect of annuals.

Why no insects at your petunias? European honeybees are in severe decline, as anyone walking barefoot in a lawn with clover knows - no need to stare continuously at the ground to avoid stepping on a bee. Petunias are, structurally, not ideal for butterflies - the big funnel is awkward for them. What butterflies really like are plants with lots of little flowers in a cluster, such as asters, eupatorium (joe-pye weed), chives, dill, Queen Anne's lace, echinacea(coneflower), and yarrow. Some butterfly species are also in decline.

The best thing to help butterflies is to plant lots of varieties they like, both for nectar and as food for the caterpillars. Many books have been written about butterfly gardening, and these Web sites have lists of favorite plants of various butterflies: http://hgic.clemson.edu/factsheets/hgic1701.htmand http://www.extension.umn.edu/distribution/horticulture/DG6711.html.

Q: I have decided that oakleaf hydrangea is just too much for my small urban garden. I want to dig it up and put it in the garden at the church where I work. But it's next to an English boxwood that I rather want to keep.

What's the best method for removing it without hurting the boxwood, and when is the best time?

A: Wait till October to move the oakleaf hydrangea, though you can do some preparatory work now. Keep in mind that oakleaf hydrangea (H. quercifolia) can have a generous root run, but since you want to protect the boxwood, you'll probably end up severing some of the oakleaf's roots. In the area between the two, use a sharp, square-corner spade to cut a line into the soil 12 inches or deeper. Use the spade to pry the soil open, about an inch wide, and fill with sand. Mark the line with several old plant tags (from annuals or whatever). Water well. From now until fall, both the boxwood and the hydrangea should recover from any shock, sending out little feeder roots from the cut roots.

In the fall, the plant tags will tell you where the cut is. Use a garden fork to reopen the cut (the fork will do less damage to the new root growth), and dig - preferably farther out - on the other sides of the hydrangea to remove it.


Send questions to Michael Martin Mills, The Inquirer, Box 41705, Philadelphia, Pa. 19101 or gardenqanda@earthlink.net. Please include locale. Read his recent work at http://go.philly.com/ michaelmartinmills.