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Garden Detective: Squash flowers, hydrangeas and coneflower 'sprouts'

Male and female zucchini flowers need to be

Male and female zucchini flowers need to be open at the same time for pollination to occur.  Credit: Jessica Damiano

DEAR JESSICA: My zucchini and squash plantings are producing flowers but no vegetables. Do you have any idea of the cause or how to remedy? In the past, we have had very good luck with these plants, resulting in enormous zucchini and squash. — Charles Buthmann, East Meadow

DEAR CHARLES: A lot of folks are reporting poor zucchini performance this year, and it's due to poor pollination.

Zucchini are monoecious, which means they produce both male and female flowers on the same plant. This allows their flowers to become pollinated without the need for nearby plants of the opposite sex. Oftentimes, however, the timing of the presence of male flowers on a plant does not coincide with the presence of females. This is especially common at the beginning of the season, as males tend to appear first. Usually, this corrects itself as the season progresses, and males and females eventually bloom at the same time, resulting in the maturation of fruit (flowers of both sexes need to be open at the same time so that insects can transport pollen from males to females). When this doesn’t happen, either female flowers simply drop off the plant or the zucchini begin to grow and then wither. Weather may also play a role, as consistently high temperatures can reduce the viability of pollen.

You can intervene by hand-pollinating your plants. First, identify your flowers: Males are attached to the plant with a simple stem; females have a swollen base that will grow into zucchini. In the morning, when flowers are open, remove an open male and pick off its petals, leaving only the yellow stamen on the stem. Touch the stamen several times to the center of each open female flower. Alternately, you can leave the male flower in place and collect its pollen with a cotton swab, and touch it to the center of the open females. Then sit back and await your zucchini.

DEAR JESSICA: I have a blue mophead hydrangea. I tried looking it up online but am confused. The flowers are fading and the plant is getting too big. How do I cut it back? Thank you, and try to stay cool. — Nancy Groben, Floral Park

DEAR NANCY: It sounds like you have a macrophylla species. These should be pruned as soon as all the flowers fade, but never after September, which would endanger next year’s blooms. Remove weaker stems from the base of the plant, being careful to retain several stems of old wood, which will produce buds for next year's flowers. Visit newsday.com/hydrangeas to identify other species and see my pruning recommendations for each.

DEAR JESSICA: Have you seen this before in a coneflower? It looks like new miniature plants are growing on top of the old. Also these Echinacea were white flowering three years ago, but are purple now. I also have ones that were yellow and orange, which have all come back purple, as well. The nursery where they were purchased says that’s not possible! — Mary Hallam, Lynbrook

DEAR MARY: The flower’s seed head has sprouted while still on the plant. Although unusual, you aren’t the only reader to report such a coneflower occurrence this year. It would seem the heat has led to premature seed germination.

Regarding the white flowering plants now producing purple flowers: That’s a case of a hybrid plant reverting to the original. Coneflowers (Echinacea) are naturally purple, but some have been bred to bloom in different colors, including white, yellow and orange, as yours were. But a plant’s genetics can be strong enough to overcome cross breeding, and often do. I’m sorry to say there’s nothing you can do about that.

ALERT: DRY, FALLEN LEAVES

DEAR READERS: Dozens of readers have written or reached out on social media about tree leaves turning brown and falling as if it were autumn.

The cause, predictably, was Tropical Storm Isaias, which brought strong, mostly dry winds to Long Island and the area. Those winds simply desiccated, or dried up, the leaves. And points south and east were cursed with a double whammy: desiccation plus wind-borne salt spray to further dehydrate foliage that likely already was dry because of the heat wave and dry conditions.

All is not lost, however. You can save most of your trees and shrubs (perennials, too) by watering very deeply at least once a week for the rest of the growing season. They need a lot of water now to help replenish what they've lost and regain their footing. If you suspect salt spray also affected your trees, rinse them off in addition to watering.

Otherwise healthy trees and plants should be fine next year.

SEND QUESTIONS for the Garden Detective to Jessica@JessicaDamiano.com. Please include your hometown. Questions can only be answered in this column.

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