Ciscoe Morris, Seattle Times garden writer, answers readers' questions about overwintering flowering maples, growing persimmons in Western Washington and ridding a greenhouse of whitefly.
Q: I have several flowering maples planted in my garden. Will they survive the winter if I leave them outdoors?
A: The hardiest and most likely to survive outdoors is Abutilon megapotanicum, the one that is cloaked in small red and yellow flowers. Unfortunately, there’s little information available regarding the hardiness of most other varieties, and although some types are fairly hardy, most succumb even in mild winters.
If you want to be sure that other varieties will survive the winter, you’ll have to pot them up and overwinter them in the house as houseplants. If that isn’t possible, you can try overwintering them in an unheated garage.
They require as bright a location as possible such as in front of a south or west facing window or under grow lights.
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Wait until freezing weather is forecast before moving them inside. The showy flowers often last well into December and are a much appreciated food source for our hummingbirds.
In an unheated garage, survival is risky. Flowering maples root easily in water, so take cuttings of your favorites, place in a vase and bring them into the kitchen. That way, you’ll be covered just in case.
Q: Is it possible to grow persimmons in Western Washington?
A: Persimmons have a delicious, unique flavor, and the trees are absolutely beautiful, especially in fall when the leaves turn a rich red, and the ripening fruit hang like bright orange lanterns throughout the tree. It is possible to grow persimmons in our area, but you have to pick the right varieties. There are two kinds of persimmon, Asian and American.
The Asian types are self-fertile and generally are smaller growing trees that can be easily maintained at 15 feet tall. The only Asian persimmon that ripens reliably in the Pacific Northwest is ‘Saijo.’ Once they ripen up and turn soft, generally after a frost, the small, acorn-shaped fruit are sweet as honey.
American persimmon trees are much hardier, ripen earlier and grow to at least 35 feet tall. Most require a cross pollinator, but ‘Meader’ is self-fertile and ripens well here.
Both of these kinds of persimmons produce astringent fruit. Don’t even think about biting into one until it is very soft.
Q: Is there a way to rid my greenhouse of whitefly without resorting to chemical pesticides?
A: Anyone who has ever had to deal with whitefly in a greenhouse knows how quickly these sucking insects that flutter about like white moths build up to damaging numbers. Each adult female is capable of laying up to 25 eggs per day!
Control is difficult because at any given time the insects are present as eggs, nymphs, pupa and adults. Furthermore, some stages such as egg and pupa are practically immune to most treatments.
Although rarely 100 percent effective, there are natural controls that can significantly reduce infestations. These include vacuuming up the adults, hanging yellow sticky cards to attract and capture adults, spraying with pyrethrum or neem oil, (sprays must be applied every five days) or you can forgo the sprays and instead, release Encarsia Formosa (tiny wasps) that are capable of parasitizing up to 100 immature whiteflies each.
If you are willing to sacrifice your plants, the easiest method is also the most effective. Whiteflies cannot survive without a live food source, so if you can clear the greenhouse of all plants, including weeds, for a period of at least two weeks it will totally eliminate whitefly from your greenhouse.
As long as you carefully inspect any plants to prevent reintroducing these troublemakers back into your greenhouse, it should remain whitefly free.
Ciscoe Morris: ciscoe@ciscoe.com; “Gardening with Ciscoe” airs at 10 a.m. Saturdays on KING 5.