propagating and grafting Ginkgo biloba

Onto what root stock should I graft a Ginkgo biloba scion?

According to The Complete Book of Plant Propagation (Taunton Press, 1997, Jim Arbury et al.), Ginkgo biloba can be propagated without grafting, by taking semi-ripe cuttings in midsummer and dusting them with rooting hormone and potting them up in a mixture of half peat, half sand/vermiculite. Cuttings should root by spring if kept moist, and need to be planted out once they have roots.

If you wish to graft it, you need a Ginkgo biloba rootstock, which you could grow from seed if you have access to a female ginkgo tree (they are hard to find), and (according to the American Horticultural Society Plant Propagation manual) you can use a whip-and-tongue or spliced side veneer graft done in late winter. The AHS manual also recommends taking softwood cuttings in late spring or early summer for ginkgo.

There is also helpful information from The Ginkgo Pages and Plants for a Future Database, which says that softwood cuttings are taken in spring, semi-ripe cuttings are taken in July and August, and hardwood cuttings are taken in December, and all are kept in a frame.

growing Hibiscus from cuttings

Can you tell me how to grow Hibiscus from cuttings?

According to the American Horticultural Society, most hibiscus root easily from cuttings. They suggest the following in Plant Propagation (1999, p. 131 and pp. 100-101):

“…cuttings should usually be 1.5 to 2 inches long, with two or three pairs of leaves retained at the top…remove the soft tip from each cutting, because it is vulnerable to both rotting and scorch…remove the lowest pair of leaves to make it easier to insert the cutting into the medium…make a hole in the medium with a pencil…[for]…minimal resistance…the cuttings will benefit from a warm, protected environment…when the cuttings root, knock them out of the container and gently pull them apart. Pot singly…”

The AHS suggests using rooting hormone and they also point out that due to timing, you may get ‘greenwood’ (slightly hardened) rather than ‘softwood’ cuttings; they are treated the same way.

North Dakota State University Extension has propagation directions including from cuttings.

I also looked at Houzz (formerly GardenWeb), a gardening forum where experienced gardeners share their knowledge. Here is another link from this site which suggests layering, a process by which you bend a branch down to soil (usually in a pot), anchor it, and wait for it to take root.

Here is additional information about layering hibiscus, from Hibiscus World.

drought-tolerant native grasses

I am looking for a native, drought-tolerant grass for a small garden plot in Seattle. Can you suggest a grass that is 2-3 feet tall and at most 2 feet wide.

Native grasses that will do well in a dry meadow setting and grow 2-3 feet tall are:

Festuca idahoensis, Idaho fescue
Bromus carinatus and Bromus marginatus, brome grasses
Elymus glaucus, wild rye grass
Melica species, onion grasses
Calamagrostis nutkaensis, Pacific reedgrass

Each of these grasses grow in very distinct shapes–I recommend that you look at them before choosing which species to plant. Fescues are popular grasses for gardens because of their fine blades and pretty seed heads. Additionally, the Elymus and Bromus will grow much more quickly than the other species.

You can perform searches on each of these species at the USDA Plants Database by typing the plant name into the Plants Name search box–this database will give you additional information about the species and some pictures.

The Washington Native Plant Society website has a list of native plant vendors.

December pollen-producing trees

What could cause sinus allergy symptoms every December?

According to Thomas Ogren’s book, Allergy Free Gardening , the genera Alnus, Baccharis, Casuarina, Festuca, Pennisetum, Juglans, Poa, Tamarix, Taxodium, Thujopsis, Xylosma, Zelkova, and palm trees all produce pollen during December.

(Source: Ogren, T.L., Allergy-Free Gardening: The revolutionary guide to healthy landscaping , 2000, pp.262-265)

Also check out Allergy Free Gardening website. There are a number of articles on low-allergy gardening listed.

Washington native plants

Is incense cedar native to Washington state? And is the Garry oak native to Kitsap County, Washington?

Although incense cedar, Calocedrus decurrens, grows in Washington State, it is not native. According to the Sunset Western Garden Book (2001), incense cedar is native to south and central Oregon, California, western Nevada, and northern Baja California.

The Washington Native Plant Society does not include Garry oak, Quercus garryana, on their list of plants native to Kitsap County, but this tree will grow there.

A list of plants native to Kitsap County

More information on Garry oak at this link

Both of these links are part of the Washington Native Plant Society website.

propagating Japanese umbrella pine

How can I propagate a Japanese umbrella pine?

Peter Thompson’s book, Creative Propagation (Timber Press, 2nd ed., 2005), states that Sciadopitys verticillata can be propagated by seed or by cuttings (the latter method in autumn, early winter, or early spring). Seeds will grow into the form inherited from the parent trees; cuttings vary. On page 153 of his book, Thompson says that the cuttings can be taken from almost any part of the plant, but he recommends using cuttings from the leader shoot in order to get a symmetrical tree with an upright leader.

There is information on propagation which comes from the USDA Forest Service National Seed Lab’s profile of Sciadopitys verticillata (no longer available online). Here is an excerpt:

“The seeds should be sown in the fall or stratified for sowing in the spring. Umbrella-pine is not easy to grow and is extremely slow-growing when propagated from seed (Halladin 1991). It has a tendency to form several leaders. Field planting has been done with 3+2 and 4+2 stock (Dallimore and Jackson 1967). Umbrella-pine can also be propagated by layers or by cuttings of half-ripened wood in summer (Bailey 1939). A nursery in Oregon propagates solely by cuttings because of faster results; Halladin (1991) describes the technique in detail.”

cat-facing and other tomato diseases

My unripe green tomatoes (‘Old German’ variety) have developed a very weird appearance: lots of lumps and bumps, and nooks and crannies, plus strange discolored blotches. What is causing this? And will I be able to salvage (and eat!) them?

There may be more than one problem here. I definitely see a physiological disorder called cat-facing in the photo you sent us. University of Massachusetts Extension provides this information about it:
“Cat-facing is a physiological disorder of tomatoes. Cat-face originates in the early stages of flower bud development and is the result of abnormal development of plant tissue between the style and ovary which results in misshapen fruit. Other impediments to flower bud development can also result in cat-facing. The syndrome is related to unfavorable growing conditions, in particular several days below 60 F when the plants are young. High levels of soil nitrogen and excessive pruning aggravate the problem. Accidental exposure to phenoxy herbicides can also lead to malformed fruit. Cat face is more prevalent on large-fruited, fresh market tomato varieties. Good growing practices, especially temperature control, should be followed in greenhouse production of field transplants. Excess nitrogen, aggressive pruning, and accidental exposure to hormonal herbicides should be avoided.”

The book Epic Tomatoes by Craig LeHoullier (Storey Publishing, 2015) says that catfacing occurs more often in large varieties that also have large blossoms. Some older varieties (heirlooms) have this tendency. Plants put out in the garden when it is too cool can also develop this appearance later. And too much nitrogen worsens it. As early as the 19th century, plant breeders were attempting to breed out this characteristic in favor of more uniform, smooth-looking fruit, but many heirloom tomatoes much-sought for their flavor tend to have this bumpy look. A little bit of catfacing shouldn’t render your tomatoes unusable. I have grown Cherokee Purple tomatoes that often have some cat-facing, but they are still delicious.

Depending on the cause of the spots, the tomatoes may or may not develop to the point of ripeness and if they do, there may be some parts that rot and some parts which are still edible. Also depending on the cause, you may decide to pull out any affect plants and dispose of them.

It’s possible that those discolored spots are due to sunscald, but the pattern of the discoloration looks more like a virus. LeHoullier says that plants which are heavily pruned or have lost a lot of foliage are more vulnerable to sunscald. However, the discoloration on your tomatoes resembles a mosaic virus, such as tobacco mosaic virus. If you are growing Nicotiana in your garden, debris from that plant as well as tomato plant contact with any tobacco products (cigarettes, or the hands that have held them, etc.) could introduce the virus to your tomatoes through any small wound—such as a pruning wound or accidental damage to plant tissue.

Washington State University Extension’s HortSense webpage has useful information on mosaic viruses
as does University of Minnesota Extension.

Still, the best thing to do is bring samples to your local Master Gardener Clinic. Many tomato problems look similar (viral, bacterial, stink bug damage, hornworm feeding). There is a good visual guide from Missouri Botanical Garden but an in-person diagnosis is best.

Witch-Hazel and its common and botanical name

Where does witch-hazel get its common and botanical names? Is it related to hazel?

You ask a great question, and the answer is confusing. The scientific (botanical) name, Hamamelis comes from the Greek words for ‘together with’ (hama) and ‘fruit’ (melis), according to A Manual of Plant Names, 2nd revised edition, by C. Chicheley Plowden (George Allen & Unwin Ltd., 1970), and it is so called because “the flowers and the fruit are on the tree at the same time.” Or it may be the Greek for “a plant with a pear-shaped fruit, possibly the medlar,” according to William T. Stearn in his Stearn’s Dictionary of Plant Names for Gardeners (Cassell, 1992). Or perhaps ‘melis’ refers to melon, as this page (now archived) from the Holden Arboretum website contends:
“The name Hamamelis is from the Greek hama (together with) and melon (apple or fruit) referring to the fact that the common witch-hazel flowers when the fruit is ripe in fall.”

Whether ‘melis’ refers to fruit, pear-shaped fruit, or melon is not elucidated by An English-Classical Dictionary for the Use of Taxonomists (compiled by Robert S. Woods; Pomona College, 1966), which lists ‘carpos’ for fruit, ‘apioides’ for pear-shaped, and ‘melopepon’ for melon (but meaning apple-shaped, or apple-gourd). The fruit of the witch-hazel is fairly inconspicuous and doesn’t resemble apples, pears, or melons, but one could make a case for its resemblance to medlar.

About the common name, Holden Arboretum says, “Witch is a corruption of wice, Old English for lively or to bend. In Great Britain, a divining rod in the hands of a dowser would become ‘lively’ when it came near an underground water source, pointing to the spot to dig a well. While the ‘witch-hazel tree’ that these divining rods were cut from in England was an elm, Ulmus glabra, American colonists found a suitable replacement in Hamamelis virginiana, which has since been known as a witch-hazel.” Plowden’s book offers an alternate spelling of the common name, ‘wych.’

Hazel is Corylus, which is in the family Betulaceae, while witch-hazel is in the family Hamamelidaceae. I think the connection between witch-hazel and hazel has more to do with a certain similarity of appearance of the leaves.

on the edibility of columbine flowers

I’ve been reading up on permaculture and exploring the edibility of common ornamental plants. Several books I’ve looked at suggest that columbine flowers (Aquilegia canadensis and Aquilegia vulgaris, specifically) are edible. I have my doubts, since columbine is in the family Ranunculaceae, which I would generally consider poisonous. What do you think?

I think you are right to question your sources. Although some species of Aquilegia have ethnobotanical uses as food, you should still proceed with caution. I found information about edible and medicinal uses of Aquilegia formosa. Daniel Moerman’s Native American Food Plants, Timber Press, 2010, mentions that the Miwok boiled and ate the early spring greens, and that children of the Hanaksiala tribe sucked nectar from the flowers. In her book Ethnobotany of Western Washington (University of Washington, 1979), Erna Gunther mentions medicinal and edible uses of this species of columbine. The Quileute tribe used the sap to aid in healing wounds, and Chehalis children sucked “honey out of the flowers.” However, The North American Guide to Common Poisonous Plants and Mushrooms by Nancy Turner and Patrick von Aderkas (Timber Press, 2009) lists Aquilegia species as toxic:
“Most [members of the Ranunculaceae] contain irritant protoanemonins; columbines contain cyanogenic glycosides.”

Columbine is included in University of Vermont Extension’s list of “Potentially Harmful Perennials.” St. Olaf College’s page on wild columbine points out a common confusion between the blossoms of honeysuckle and columbine:
“Young children often mistake Columbine for Honeysuckle, pulling off the flowers and biting the spurs in search of nectar. Though no official records of toxicity have been reported for Columbine, it belongs to a family which contains other toxic species. Caution is advised.”

The Plants for a Future database of edible and medicinal plants lists a number of species of columbine. Here is their page on Aquilegia canadensis. I don’t find myself convinced by the statement that “the flowers are probably perfectly safe to eat.” The entry for Aquilegia vulgaris says that the flowers are “rich in nectar, they are sweet and delightful, they make a very attractive addition to mixed salads and can also be used as a thirst-quenching munch in the garden. The flowers are also used as a tea substitute.” It is worth looking at the sources cited at the end of this entry, to decide if you feel they are trustworthy. To summarize, when in doubt, don’t eat the columbines (or any other plant whose edibility is debatable)!

dividing Trilliums

My native trilliums (the beautiful white ones that have now faded to purple) are thriving in my woodland garden. I would like to know when the best time is to dig up a clump to share with a friend.

According to Michael Leigh’s Grow Your Own Native Landscape (Olympia, WA: Native Plant Salvage Project, 1999), dividing Trillium is difficult because you must “dig deeply to ensure minimal damage to roots and rhizomes, take special care not to break the stems, and transplants may die back before reappearing the following spring.” According to April Pettinger’s Native Plants in the Coastal Garden (Whitecap, 2002), “Trilliums do not like to be transplanted, so if you decide to move them to another site, be prepared for them to take several years to flower again.” My personal experience suggests that taking as much of the soil around those rhizomes as possible will give the plant the best chance of success, and I think early fall is the best time, although I don’t find any source that specifies a time of year. Right after bloom may be fine too, as it is the recommended time for division according to the American Horticultural Society’s Plant Propagation (DK Publishing, 1999).