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Nandina pruning and propagation

I have a Nandina (heavenly plum blossom) that is getting really top heavy and I need to find out how to divide it or cut it back and root the cuttings. I’ve been reading up on it and there is very little information about propagating them.

 

The book American Horticultural Society Plant Propagation by Alan Toogood (1999) recommends
taking nodal greenwood (similar to softwood) cuttings in the summer. The shrub
can also be propagated by division but this is recommended in the early spring
and not in summer due to the increased risk of wilting and scorching.

Rainy Side Gardeners in the Pacific Northwest notes that fresh seed (as soon as it is ripe) can be germinated in six to eight weeks. Old seed may take up to two years to germinate. Semi-ripe cuttings can be rooted in the summer.

As for pruning the Nandina, the American Horticultural Society Pruning and
Training: A Fully Illustrated Plant-by-Plant Manual
by Christopher Brickell and
David Joyce (1996) suggests that plants can usually be renovated by cutting back
old canes to ground level in the early spring when the older leaves have turned
from red to green. Rainy Side Gardeners suggest cutting the oldest canes down to
the ground, discouraging the shrub from getting top heavy and falling over. The
pruning will keep it growing a denser growth lower down on the shrub.

A Practical Guide to Pruning: How and When to Prune for Better Shrubs, Trees,
Fruits and Climbers
by Peter McHoy (1993) suggests cutting one out of every
three canes to the ground. His recommendation is not to do this each year.

Paghat’s Garden (a website maintained by a local gardener) had this to say:

“Nandina thrives in considerable shade, but has a tendency to become leafless underneath unless it can get sunlight around the lower part of the plant.
Before I transplanted this one, it was in a lot of shade, & needed to be staked
because it became top-heavy. This did not necessarily harm its looks, because
the species’ tendency to lose leaves at the bottom gives it the appearance of a
miniature tree with long trunk, & I used the “empty” space around its base for
small ferns. But when transplanted to a sunnier garden, it became more broadly
bushy & the trunk became stronger, no longer needing to be staked.”

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Watering Salvias

I recently planted several purple Salvia plants that have completely faded from beautiful, bright purple to beige. It has been really hot and dry and I’ve been watering them in clay soil once to twice a day. Is it possible that I’m overwatering them? Or do they need even more water since they were just planted?

 

I’m not sure what type of Salvia you are growing, but it is possible you are overwatering them. The heavy clay soil combined with watering 1-2 times daily sounds like too much for a plant that is drought-tolerant once established. To learn more about growing ornamental salvias, see this University of California, Davis Arboretum Review, #44, Fall 2003 article, “Salvias for Every Garden” by Ellen Zagory.

I would suggest watering less often, but watering more deeply, and possibly mulching around the plants. Some xeriscaping resources suggest using gravel, and it is mentioned in “Landscape Water Conservation: Principles of Xeriscape” from New Mexico State University Extension, with the caution that although “some plants native to very well drained soils grow better in gravel mulches […] rock mulch becomes very hot in our climate and can injure or limit growth of some plants. Ultimately, the mulch should be shaded by landscape plants that will provide environmental cooling. Using gravel mulch alone as a landscape element may result in increased home cooling bills and require greater weed control efforts.”

This article by Seattle-area garden writer Ann Lovejoy on drought-tolerant gardening may also be of interest.

 

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Amaryllis and syrphid flies

My Amaryllis bulbs are infected with syrphid flies. I have dug them but don’t know what to do with the bulbs. What can I do to save them?

 

Until receiving your question, I had always known of syrphid flies as beneficial insects in the garden, so I considered the possibility that the bulbs might be infested with bulb mites, or mealybugs, which are fairly common pests of Amaryllis. That being said, in my research to answer your question, I came across an article by Whatcom County Washington State University Extension agent Todd Murray which describes the Narcissus bulb fly, which is indeed a syrphid fly, and does sometimes infest Amaryllis bulbs. Excerpt:

Monitoring and Management: There are no pesticide recommendations available for these bulb flies. But that’s O.K.; we have many alternatives that we can use to avoid mushy bulbs. You should be thinking about trying these practices if you have a problem with bulb flies.

  • In May, on sunny days look for large bumblebee-like flies hovering around your flowers. Bumblebees will have two pairs of wings while bulb flies will have one. Grab your handy insect net (you all have one, right???) and catch the critters before they can do too much egg laying. This sounds tedious, but is very effective for protecting small plantings of susceptible bulbs. Remember, each female fly can lay up to 100 eggs! Plus, if it is a nice sunny day, you should be outside admiring and tending your garden anyway.
  • Adult flies use visual cues and smell to locate your delicious bulbs. After you have enjoyed your flowers, cover the bulb bed with a floating row cover, like Reemay*. Another recommendation given suggests that you mow down the vegetative portions of your plant and gently cover the tops with soil. Female flies will be unable to locate the bulb. Once no new foliage is sprouting, remove and store
    the bulb through the off-season. If you do this, I do not know the impacts this will have on next year’s flower. That vegetation produces the bulb’s energy reserve that is needed for next year’s growth. Regardless, the earlier you can pull your bulbs out, the better chance that you will avoid bulb flies.
  • Bulb flies are less active in open, windy areas. Plant your beds in exposed windy places, if your landscape provides this type of climate.
  • Avoid any damage to the bulbs when handling and planting. The lesser bulb fly prefers damaged goods to healthy bulbs. Establishment of maggots is much easier if there are already rot producing organisms in the bulb.
  • Plant your bulbs deep, if they can tolerate it. Bulbs planted 25cm (or about 10″) deep in the soil will evade attack by adult flies. I am unaware if planting this deep is practical.
  • When the time comes to pull up the bulbs, check the basal plate of each bulb. When you purchase new bulbs, check the plate for any signs of squishiness and rot. If you find some rot there, do not plant them and discard the rotten bulbs.
  • Infested or suspicious bulbs can be cleaned of maggots by soaking bulbs in hot water (43-44 C) for at least 40 minutes. Care must be taken to not exceed this temperature, because you will damage the bulb. This is a great way to kill other pests of bulbs, too.
  • Finally, if the problem persists, the sure-fire way to avoid bulb flies is to buy your flowers at the store like all the non-gardeners and black-thumbers out there. If you don’t plant it, they won’t come. This option is the one that I’m going to take now.

In the event that there are other pests present on your bulbs, this information from University of Florida Extension may be of interest. Excerpt:

“Spider mites are tiny animals (1/50 inch or 0.5 mm long) that cause injury similar to that of sucking insects as they feed on the leaves of amaryllis during warm, dry periods. Bulb mites attack rotting bulbs and tunnel into healthy bulbs, transmitting organisms that produce bulb rot.
Bulb mites are particularly damaging to bulbs of amaryllis.
Mealybugs are soft-bodied insects covered with a white, waxy material. When mature, they vary from 1/50 to 1/3 inch (0.5 to 8.5 mm) in length. They damage plant foliage by sucking plant fluids and may invade stored bulbs. Some control can be obtained by frequent syringing with a hose.”

In case you are curious, here is information on the beneficial properties of syrphid flies, from University of California, Davis Integrated Pest Management.

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Propagating Cyclamen

I have a Cyclamen that blooms in the fall, so I think it would be
C. hederifolium. Right now there is a clump of 1/2 in. diameter
“seeds” attached to curly spirals. I’m wondering if I can harvest those seeds and give them to others. In the book I’m reading, they say it is propagated by corms, which I assume I
would find if I dug them up. What should be done at “cleanup time,” which seems to be about
now, as there are only a few dried up leaves left, and all those
“curls and pods.” I’ve had it several years and have done nothing to it. It
blooms beautifully in the fall each year with deep pink flowers. I
do see tiny starts at various places in the yard, so some seeds
have moved around.

 

Propagation by seed is the most commonly recommended method according to the following resources:
American Horticultural Society Plant Propagation: The Fully Illustrated
Plant by Plant Manual of Practical Techniques
by Alan Toogood, The Royal
Horticultural Society A-Z Encyclopedia of Garden Plants
by Christopher
Brickell, The Complete Book of Plant Propagation by Jim Arbury, Richard
Bird, Mike Honour, Clive Innes and Mike Salmon, The Plant Care Manual by
Stefan Buczacki and Cyclamen; A Guide for Gardeners, Horticulturists and
Botanists
by Christopher Grey-Wilson. Apparently propagation from corms
is technical and difficult. However, if you choose to give it a try, the
title Cyclamen, mentioned above, does go into some detail about the
process.

You can thank the ants for the tiny starts you are finding in your yard,
they eat the “sweet and sticky mucilage” that covers the seed, they
then leave the seed alone where it lies, ready to germinate on its
own afterward. Here is an article by Rebecca Alexander from the Spring 2017 Washington Park Arboretum on . (Cyclamen) As for the clump of seeds you are finding on
your plant, their dark brown color indicates they are ripe and ready for
sowing. They require dark, cool temperatures for germination (43-54 F)
for C. hederifolium. It is recommended that the seeds soak for a minimum
of 10 hours (a small amount of gentle detergent can be added) and rinsed
thoroughly. They can be sown at the end of summer and produce flowers in
about 14 months. (The Royal Horticultural Society A-Z Encyclopedia of
Garden Plants and American Horticultural Society Plant Propagation
).

Unfortunately I couldn’t find much information for your question
regarding clean up. However, I would suggest that it would be perfectly
acceptable to remove the dead leaves and seed pods, including the curly
spirals that are attached to them. You can choose to sow the seeds
or give them away to friends. As long as you don’t disturb the exposed
curled tubers that may be present at or near the surface of the soil, I
think you’ll plant will be fine. You may also want to consider adding
additional plants that show their true colors in the summer when your
Cyclamen is dormant. This would mask the appearance of your Cyclamen and
perhaps dissolve any need for clean up.

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Deadheading lilies

How do you remove the dead flowers from a Asiatic lily? Do you go to the main stem and cut it there or do you just remove the flower and leave the pod?

 

Here is what South Dakota State University advises:

“Once all the flowers have dropped their flower petals, it is a good idea to deadhead the stem, by cutting of the flower spike at the base, just above the stem leaves. Keep in mind that the leaves are the most important plant component to allow the lily to come back next year and flower even more than the year before. So, keep those leaves green and healthy all the rest of the summer and fall so they can help to store up food reserves for the winter and next year’s growth and flowering.”

The practice of deadheading the spent flowers (but leaving the foliage as long as it is green) enables the plants to put energy into the bulb. Once the foliage dies back in late fall of early winter, you can cut down the dead stalks.

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Corpse plant or voodoo lily?

I recently purchased a house that has a relative of the
corpse plant in the yard. It is a perennial about 30″ tall and has
been in bloom since yesterday with a deep burgundy bloom that is
about 10″ long. It has delicate, deeply lobed leaves.

Any idea what it could be or how to care for it? I was considering
transplanting it since it sits just below our dining room window,
under the eave of the house. Stinky! I imagine it will only bloom
for a short time. Could it be rare?

 

I am guessing that what you have is the voodoo lily, or Dracunculus
vulgaris
.

The website of a Pacific Northwest gardener, Paghat, has information about this plant with pictures for you to compare with the plant in your garden. Vanderbilt University also has images of this plant on its Bioimages page.

For contrast, here are images of corpse flower, Amorphophallus titanum.

According to The Royal Horticultural Society’s A to Z Encyclopedia of Garden Plants
edited by Christopher Brickell (DK Publishing, 1996) the plant you have
is frost-hardy, and grows best in full sun but will tolerate partial
shade. You can protect it with a winter mulch. Native to the
Mediterranean, Madeira, and the Canary Islands, they grow well in open
glades in sheltered woodland, or at the base of a sunny wall. From what I
have heard from other gardeners (we receive several questions a year
about this plant), they do spread over time. If you wish to increase
their numbers, they can be propagated by separating offsets in fall or
spring.

Recycling plastic pots

Do you know of a source in the greater Seattle area or North Puget Sound that will take and recycle 1 gallon black plastic pots that nursery stock comes in?

 

If you have recycling service in the city of Seattle, you may put clean plastic plant pots in your recycling bin. If you do not have access to recycling, here are some other options. Search “plastic nursery pots” on King County’s What Do I Do With… website. Several nurseries are listed, including West Seattle Nursery, Clinton Bamboo Growers, Molbak’s, and Flower World.

You can also contact the Washington Park Arboretum’s Pat Calvert Greenhouse to see if they are accepting nursery pots. Call 206-325-4510 or email info@arboretumfoundation.org.

What causes autumn leaves to stain concrete?

Each year, in early autumn, I notice tree leaf silhouettes staining the sidewalk. Do all trees do this? I mainly see maples and occasionally oak leaf shapes. What substance in the leaves causes this staining effect?

 

Tannin in the leaves is responsible for leaving behind those silhouettes. Rain rinses the tannins from the fallen foliage, and leaves a trace. The prints are most visible on lighter colored surfaces. This is similar to the way strong black tea leaves a tannin stain on porcelain cups and tooth enamel.

The very word ‘tannin’ has its origins in the Latin, tannum, meaning the bark of an oak tree (which was used to tan animal hides to make leather). Oak has especially high levels of tannins, but because its leaves are thick and take longer to decompose, you may notice fewer leaf prints from oak trees.

Tannins are widespread in many different plants, and may be present in many parts of a plant. They are especially common in leaf tissues, “particularly in the cells of the upper epidermis (on the top surface of a leaf).”

The substance may also be found in the bark and wood of trees, as well as the buds, stems, fruits, seeds, roots, and plant galls, where it may provide protection to the plant. For example, cottonwood trees can adjust their level of tannins to defend against beavers harvesting their wood.

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On the edibility of fiddleheads

Are Bracken fern fiddleheads edible? The very old Euell Gibbons edible plant books say it’s o.k. but I’ve heard rumors that it is toxic and shouldn’t be eaten. Do the edible Ostrich Ferns grow in western Washington? I have lots of sword ferns, but nobody seems to mention if they are edible.

 

The fern whose fiddleheads are most commonly (and perhaps most safely) consumed is the ostrich fern, Matteuccia struthiopteris. According to Sue Olsen’s Encyclopedia of Garden Ferns, this plant will grow “in the severe and forbidding climates of Newfoundland and Alaska,” but they do not do well in areas with hot summers. We do occasionally have hot summers in Washington State, so that could pose a challenge, but if you suite the plant in an area with some shade, it might survive a heat wave.

The University of Maine Extension has a factsheet entitled “Facts on Fiddleheads” which mentions the health risks associated with their consumption, and offers tips on how to avoid illness. Note also, this Centers for Disease Control and Prevention page on Ostrich Fern Poisoning.

An article in Fine Gardening discusses which fern fiddleheads are safe to eat.
Excerpt:
“Throughout the world, several types of fiddleheads are eaten, though most contain toxic compounds. The most commonly eaten and most esteemed fiddlehead is that of the ostrich fern (Matteuccia struthiopteris, USDA Hardiness Zones 2-8), often simply called fiddlehead fern. The ostrich fern is the safest fern to eat, even though it, too, can contain toxins. The fiddleheads of cinnamon fern (Osmunda cinnamomea), lady fern (Athyrium filix-femina), and bracken fern (Pteridium aquilinum) can also be eaten, but all are at least mildly toxic and can cause nausea, dizziness, and headache, so it’s probably best to avoid them. The safest way to eat fiddleheads is to stick to ostrich ferns and to eat them in small quantities.”

Below is information specifically about bracken fern, Pteridium aquilinum.

Handbook of Poisonous and Injurious Plants by Lewis Nelson et al. (New York Botanical Garden, 2007) says that all parts of the plant are toxic. The toxin is thought to be ptaquiloside, a sesquiterpene.

From the Earl J. S. Rook website (no longer available online):
“Most commonly used today as a food for humans. The newly emerging croziers or fiddleheads are picked in spring and may be consumed fresh or preserved by salting, pickling, or sun drying. Both fronds and rhizomes have been used in brewing beer, and rhizome starch has been used as a substitute for arrowroot. Bread can be made out of dried and powered rhizomes alone or with other flour. American Indians cooked the rhizomes, then peeled and ate them or pounded the starchy fiber into flour. In Japan starch from the rhizomes is used to make confections. Bracken fern is grown commercially for use as a food and herbal remedy in Canada, the United States, Siberia, China, Japan, and Brazil and is often listed as an edible wild plant. Powdered rhizome has been considered particularly effective against parasitic worms. American Indians ate raw rhizomes as a remedy for bronchitis.
Bracken fern has been found to be mutagenic and carcinogenic in rats and mice, usually causing stomach or intestinal cancer. It is implicated in some leukemias, bladder cancer, and cancer of the esophagus and stomach in humans. All parts of the plant, including the spores, are carcinogenic, and face masks are recommended for people working in dense bracken. The toxins in bracken fern pass into cow’s milk. The growing tips of the fronds are more carcinogenic than the stalks. If young fronds are boiled under alkaline conditions, they will be safer to eat and less bitter.”

The book Ecosystems and Human Health by Richard Philp (CRC Press, 2001) states that “considerable evidence exists that bracken fern produces bladder cancer in cattle that eat excessive amounts when better fodder is unavailable, and in rats fed large amounts of it. Because the young shoots, called fiddleheads because of their curled shape, are eaten as a delicacy in many parts of the world, including Canada and Japan, there has been concern over potential for carcinogenic effects in humans. At one point, it was suggested that the relatively high incidence of bladder cancer in Japan might be related to consumption of bracken fern. Epidemiological studies, however, have failed to demonstrate such an association, and it is now felt that eating fiddleheads does not constitute a risk factor for cancer.”

This Northwest gardener, Paghat, also discusses the toxicity and edibility of bracken fern:

Excerpt:

“While causality for human illness from eating bracken is not proven, plausibility is present. Toxins break down in cooking, but the traditional light frying or quick parboiling is insufficient to break down potentially harmful chemical components. Bracken should be cooked at high temperatures to be safe, and are quite easy to prepare correctly in woks.

It is not recommended to eat rare bracken under any circumstances because of the statistical increase in cancers in countries where brackens are a consumed in high numbers. Ostrich Ferns are of such low toxicity as to be far preferable to meet the dietary interest in fiddleheads. But as a well-cooked food item eaten only occasionally, there is no indication of risk from bracken. Plausible risk is restricted to the accumulative effects over time from consumptions of high amounts of bracken parboiled or so briefly cooked as to still contain toxins.”

Sword fern (Polystichum munitum) growing in the wild is seldom browsed by herbivorous animals because the rough foliage is fairly repellent. That specific epithet ‘munitum’ in the scientific name means ‘armed.’ You may have seen information about Native Americans roasting the rhizomes and eating them, but this was a famine food resorted to when other resources were scarce. (The leaves were used to line fire pits for cooking, according to Frank Tozer’s book, The Uses of Wild Plants, 2007). I would not take unnecessary risks experimenting with plants that are not typically considered edible.

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Historic plantings in Washington Park Arboretum

I am researching the early years of the Washington Park Arboretum for a historical narrative I’m writing. Can you tell me what is growing near the footbridge from E. Lynn Street into the Arboretum in a January 1912 photograph? Do you know when the bridge was constructed?

I did find a 1935 plan from the Olmsted archives which seems to have a full inventory of plants, but some of the abbreviations escape me.

I am seeking any other online sources that might help in my research.

 

The bridge, designed by the architects William Sayward and Walter Willcox, was built in 1910, and at the time was referred to as the Arboretum Sewer Trestle or the Arboretum Aqueduct. Because the photo was taken in winter, it does not provide useful clues about the bare shrubs and trees. However, the 1935 plan does yield information, assuming some of those plants would have been there at the time of your photo. I can decode some of the abbreviations (such as Syc for sycamore, V.M. for vine maple, and Cot for cottonwood, W for willow, and A could be alder), and an awful lot of “Cat,” which turns out to be Catalpa, according to the 1936 plan’s Legend of Trees in the high resolution version of the image.

In addition to the Olmsted archives online, you may find these links useful:


Click the image to view close-up.