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).

managing crabgrass

I used to have a pristine green lawn and it has since been overtaken by crabgrass. I’ve tried organic and chemical weed-and-feed products to no avail. What can I do to get the weeds out?

Local plant expert Arthur Lee Jacobson has written about crabgrass (Digitaria sanguinalis) in his book, Wild Plants of Greater Seattle (2008): “Crabgrass is difficult to get rid of because it seeds itself at an almost unbelievable rate; mowing simply makes if flower nearer to the ground. Control demands diligent weekly hoeing and pulling by hand, from July through at least September. Even a few specimens left to reseed ensure more seedlings next summer.”

According to Ecologically Sound Lawn Care for the Pacific Northwest by David McDonald (Seattle Public Utilities, 1999), weed invasions are best prevented by making a habit of aerating and topdressing to correct soil compaction and build fertile soil. He recommends that you “overseed at summer’s end with locally adapted grasses to fill bare areas with grass rather than weeds. Correct acidity or poor drainage. Mow higher (2-2 1/2 inches, or 1 inch on bentgrass), fertilize moderately with slow-release or natural products, water deeply and infrequently in the summer. Tolerate some broadleaf plants like clover and daisies. Hand weed or spot-spray problem weeds in spring or fall to stop them before they spread.”

There is additional information on crabgrass from University of California, Davis Integrated Pest Management.

Seattle Public Utilities has information on best practices for maintaining a healthy lawn.

Toxic-Free Future (formerly known as Washington Toxics Coalition) also has a helpful lawn care fact sheet that might be helpful to you.

Since the weed-and-feed approach to the problem was not effective (and chemical weed and feed should be avoided), I recommend trying some of the cultural controls discussed above (mow higher, only fertilize at appropriate times and don’t use quick release fertilizer, water less often but more deeply, improve drainage by aerating, build soil by mulching). Solarization might be an option if the problem can’t be addressed by hand-weeding combined with the other methods described.

sowing herb seeds in July and August

Are late July and early August still a good time to start sowing seeds for basil, parsley, and coriander in Seattle?

According to Winter Gardening in the Maritime Northwest by Binda Colebrook (Sasquatch Books, 1998), you can sow coriander in late August to early September and as long as the winter is not too harsh, you should have success. You may want to keep the plants under cover during winter.

When you sow parsley, Colebrook recommends looking for European varieties which are cold-hardier than the American type. The following article, from the British paper The Guardian (July 1, 2006 issue) discusses summer sowing:
Summer-sown parsley by Sue Stickland

Here is an excerpt:

“Spring-sown parsley often struggles, but sow now and it’s easier to get healthy plants. These should give a good crop right through to autumn, and look as decorative in beds, pots and troughs as they do on the plate.

Sow directly where it is to grow, or into small pots for transplanting, and keep it moist. In steady July temperatures, germination should take a couple of weeks (quicker by half than in spring). Plant out seedlings from pots as soon as they are big enough, and before the ‘tap’ root hits the bottom. This will give stronger, more resilient plants.

The main enemies of spring-sown parsley are aphids and carrot flies. Aphids not only make the leaves unappetising, but carry viral diseases; carrot flies tunnel into the roots, weakening the plant, just as they do with their main vegetable host. When parsley starts to yellow and redden, and plants become stunted, one or other of these pests is usually to blame. July sowings avoid the worst attacks, provided you keep them well away from any ailing plants. Never try to grow this herb in the same spot twice.

For vibrant, deep green leaves, the plant must also have rich soil and plenty of moisture. Add well-rotted manure or garden compost (or a bagged equivalent) to a garden patch, and to the potting compost in deep troughs and pots. Don’t forget them in dry spells – most herbs won’t need watering, but parsley will. When it turns cold, bring pots into a cold frame, greenhouse or other warm, protected spot. These late-sown plants will provide welcome fresh sprigs in winter and early spring.”

Basil is a half-hardy annual, and is best sown into pots in early spring, or directly into the garden in late May. I don’t think you can successfully grow an outdoor fall/winter crop. Mary Preus, author of The Northwest Herb Lover’s Handbook (Sasquatch Books, 2000), suggests potting up plants from your garden in September and moving them indoors. If given the right light and care, you can keep harvesting throughout the winter.

reversion in variegated vinca

The variegated vinca growing in light shade in my garden has lost its white borders. Should I move it to a sunnier location?

The technical term for a loss of variegation is reversion. Variegation can be affected by light conditions as well as other factors, as this information from the Royal Horticultural Society suggests: “Variegation may vary during the year and is often less apparent in late summer. Where there is a permanent loss of colour inadequate light is often the cause. Waterlogging can also lead to loss of leaf colour. Reversion may also occur where more vigorous green shoots outgrow variegated shoots.”

Here is a link to some helpful information about variegated plants, from a now-defunct website which was called Enjoy Gardening:
“Understanding all the science behind variegation is quite complicated, so here is the nutshell version. For variegation to be stable, the variegation trait must be caused by a mutated cell or a group of cells that are fit
enough to grow and multiply, and those cells must originate in a region of the plant where they are involved in generating new variegated gene cells. For example, if the mutation originates in a section of a leaf or stem where normal tissue can outgrow the mutation, the variegation pattern will often be unstable and disappear. However, when there is an ‘island’ of mutated cells within a growing point or tip, the variegation has a greater chance of
being stable… Of course, to every set of rules there are always exceptions, which is why it’s quite common for completely stable varieties of plants to lose their patterns over time. And that’s exactly what happens with some
variegated Euonymus shrubs when the ‘normal’ buds produce leaves that have more chlorophyll than the variegated leaves have. Having more chlorophyll allows the normal leaves to grow faster and to out-compete the variegated foliage. In this case, the solution to preserving variegation is to get out the pruners and to lop off the emerging threat of normalcy.”

As suggested above, you can try cutting off the non-variegated (‘normal’) foliage and hope that the variegated foliage will return to dominance.

planting hydrangeas

I would like to plant hydrangeas along a south-facing shed. The site gets some morning sun and quite a lot of afternoon sun from over the roof of the house. This area currently has moss growing on it and has not been previously used for planting. Your reply will help me to decide whether to plant there or not.

I have amended the area where I have planted the hydrangeas with chicken manure and compost. I dug holes about 14 inches deep and and about 14 inches square. I also put a spade full

Most hydrangeas will do well in sun to part shade although full sun in a hot climate would be too much. You also want to bear in mind that hydrangeas, especially Hydrangea macrophylla, prefer adequate moisture. According to Michael Dirr’s Hydrangeas for American Gardens (Timber Press, 2004), an inch of water once or twice a week should be sufficient as long as the plant’s soil needs are met (consistently moist, well-drained, acidic soil which is rich in organic matter such as leaves, compost, well-aged manure). Some species of Hydrangea tolerate heat better than others, according to Dirr. Hydrangea macrophylla, H. serrata, and H. umbellata do not fare as well as H. paniculata. Some species, like H. quercifolia and H. aspera, prefer shadier spots. Dirr recommends using drip irrigation for plantings of Hydrangea, specifically using drip tubing, extender lines, and emitters attached to a garden hose, possibly with a timer.

The Michael Dirr book says that good soil preparation (not just of the planting hole) ahead of time is the best thing for hydrangeas. He does not subscribe to the rule sometimes put forth, that the hole must be 3 times as wide as the root ball. I also consulted Hydrangeas: A Gardener’s Guide by Toni Lawson-Hall and Brian Rothera (Timber Press, 1995) which says the hole should be 2 times the rootball’s width and depth. Be sure to check the state of your plants’ roots. You want to make sure they are not coiled in a spiral or restricted in any way. You may need to tease out or prune the roots a bit before planting.

Professor Linda Chalker-Scott discusses planting procedures in her book, The Informed Gardener (University of Washington Press, 2008), advising that the planting hole only needs to be the depth of the root system, but twice the width. She also recommends against amending the planting hole in any way. Backfill the hole with native soil, not a soil amendment. The idea is not to ‘spoil’ the plant by putting rich compost just in the hole, which will deter the roots from spreading out into the surrounding area. Here is more of her writing on this subject.

You have already amended the surrounding soil, so the addition of gravel to the hole is not necessary, and is possibly not a good idea, according to general planting information from University of Minnesota Extension. Here is an excerpt: “If soil drainage is inadequate, species that are tolerant of poorly drained soils may be planted, or soil drainage may be improved. This can be done in two ways. If a hard pan is present (a compacted, impermeable layer of soil) with an underlying layer of well-drained soil, a hole can be dug down to the permeable layer to provide drainage for the planting hole. If the soil is poorly drained and there is no well-drained layer below, a tile system can be laid. This, however, is expensive and requires the assistance of a professional for proper design. Simply adding gravel to the bottom of the planting hole will further decrease oxygen availability to the root system.”

of gravel at the bottom of the hole to improve drainage as I suspect that the base soil is mostly clayey.

growing conditions for Ribes sanguineum

I received a gift today, a shrub/plant named Ribes sanguineum ‘Inverness White,’ and different neighbors have different ideas of where to plant it.

I only have a little shade in my garden. Will it take full sun, or does it need partial shade? How tall and wide will it get?

In my experience, Ribes sanguineum does best in partly sunny (or partly shady) sites, and does not need much water once established. The plant you have is Ribes sanguineum var. glutinosum ‘Inverness White.’ This cultivated variety is described by California Flora Nursery as 6 feet tall and wide, but plant size will vary with garden conditions.

University of California Berkeley Botanical Garden’s spring 1999 newsletter features flowering currant selections, including the one you have:
“Ribes sanguineum var. glutinosum ‘Inverness White’ is a proven fast grower with wonderful white flower clusters. As the flowers fade they develop a rosy cast, giving a bicolored effect. The typical form of this variety has pale pink flowers. Roger Raiche found this one on Inverness Ridge in Marin County, and it has since made its way around the state to various gardens, both public and private. This plant was featured, with other new introductions, at a national meeting of the American Association of Botanical Gardens and Arboreta […]”

leaf drop in Dogwoods

I have a couple of dogwood trees, both are about 40 years old. In the front yard is a pink dogwood approx 25 ft tall and in the backyard a white one, approx 50 ft tall. Each year in the spring for the past few years the leaves have been browning and falling off the white one. Now the pink one is beginning to develop the same symptoms. Is there anything I can do?

There are several possible causes of leaf drop in Dogwoods. Below, please find referral information for the Master Gardeners and two websites that contain information about pests and diseases of Dogwoods and methods used to control them.

To know for sure what is causing leaf drop in your trees, you may wish to consider bringing a bagged sample of the leaves to the Master Gardeners Diagnostic Clinic here at the Center for Urban Horticulture or another of the many Clinic locations. You can locate a Master Gardener Clinic within King County on this website (Plant Clinic Schedule).

You mentioned that the leaves of your trees turn brown and then drop. These symptoms are commonly found when Dogwoods have been attacked by Anthracnose.
The Washington State University Cooperative Extension’s “Dogwood Anthracnose” page may be of use in helping you determine whether your trees have this disease.

Hopefully, this information will get you started. If you would like more information or have any other questions, please be sure and let us know.

I hope that your trees recover!

insect pests that affect bamboo

I have a “fence” of golden bamboo that is approximately 8 years old. It has a black coating on the leaves as well as small white flying insects that scatter when I move the branches. Any ideas as what has invaded my yard?

While we cannot diagnose plant problems remotely, what you describe sounds a bit like aphids or whitefly.

This page (now archived) from the American Bamboo Society website also has information on insect pests that affect bamboo. Here is an excerpt, about aphids:
“Aphids love bamboo! There are over 50 species of Asian aphids known to feed on Asian bamboos. A good example is Astegopteryx bambusifoliae, which sucks sap from the leaves of Bambusa, Phyllostachys, and Dendrocalamus throughout Southeast Asia. It over-winters on the bamboo plant, where it sucks sap from the leaf undersides and culms. It is most common during the winter and spring, and disappears during hot summers. It is controlled by ladybeetles. In general, aphids aren’t a major problem since there are so many organisms that prey on them, but they can appear in an occasional outbreak that causes wilting of the leaves and shoots, a reduction in vigor, and stunted growth. They can also transmit fungal diseases, such as black mildew.” Bamboo mites are also common in our area.

University of California at Davis “Giant Whitefly” page mentions a black mold that forms during whitefly infestations.

To determine which insect is invading your bamboo, you may want to take a bagged sample to a Master Gardener Clinic for identification. For information about Clinic hours see their website (Plant Clinic Schedule).

browning of leaves in oakleaf Hydrangea

Why are the leaves of my oakleaf Hydrangea turning brown around the edges and falling off?

We do not diagnose plant problems, especially without a sample. It might be wise to bring a sample to your local Master Gardener clinic. You can locate a Master Gardener Clinic within Washington State here.

However, based on my personal experience with my own oakleaf Hydrangea (Hydrangea quercifolia), it is a semi-deciduous shrub that will hold on to its leaves through winter, only to replace them with fresh growth in the spring. All my Hydrangea’s old leaves have turned reddish-brown and look very ratty. Once new growth resumes in spring, I cut off most of the tattered leaves. (Don’t do it too early, in case there is a late frost.)

If you have new growth, do not worry about your shrub, but if you do not have new growth or it is the new growth that is turning brown then you should take a sample leaf into one of the Master Gardener clinics (linked above).