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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Rhamnus purshiana, Pyrus, Nyssa, Hovenia, Oxydendrum arboreum, Cornus nuttallii, Malus, Crataegus, Native plants--Care and maintenance, Quercus, Prunus, Acer

Can you recommend some tree species (deciduous) that can have wet feet but will also tolerate dry conditions in the summer? The recommendations should be trees that are not too messy (no cottonwoods or alders, please) and not too big. I would like to plant some trees near a swale in my yard - so they could be sitting in soggy ground during the winter.


Following is a list of possibilities, most of which come from Water Conserving Plants for the Pacific Northwest West of the Cascades (by the N.W. Perennial Alliance, 1993). The list includes only trees that 1) thrive in soils which are waterlogged in the winter, and, 2) grow to less than 40 feet tall.

ACER (maple):
A. buergeranum (trident maple)
A. campestre (field maple)
A. ginnala (Amur maple)
A. circinatum (vine maple)
CORNUS nuttallii (western dogwood)
C. douglasii (black hawthorn)
C. monogyna
C. phaenopyrum (Washington thorn)
C. x lavallei (Carriere hawthorn)
HOVENIA dulcis (Japanese raisin tree)
MALUS fusca (Pacific crab apple)
NYSSA sylvatica (black gum)
OXYDENDRUM arboreum (sourwood)
PRUNUS (prune/plum/cherry):
P. virginiana var. melanocarpa (chokecherry)
P. emarginata (bitter cherry)
PYRUS (pear):
P. communis (common pear)
P. pyrifolia (Chinese pear, sand pear)
QUERCUS (oak):
Q. acutissima (sawtooth oak)
Q. imbricaria (shingle oak)
RHAMNUS purshiana (cascara)

Date 2017-05-25
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Plant Answer Line Question

Keywords: Shade trees, Acer

We are looking for a tree to plant in our backyard to provide some shade. We live in a location that gets lots of sun. We want something that will grow quickly, develop a canopy that we can walk under, will get approximately 20-30 feet tall, 15-20 feet wide, and not need a lot of water. Evergreen is probably out of the question. Any suggestions?


I think that your best bet may be a maple. Three maple species surfaced that meet your criteria of a quick growing, 20-30 feet tall tree with an equal or greater spread, that will do well in the sun.

--Acer circinatum, the vine maple (the only downside--this may be a bit shrubby for your landscape)
--Acer ginnala, the Amur maple
--Acer palmatum, the Japanese maple (you'll need to be choosy in order to find a cultivar that will reach 20-30 feet, but there are some that do. Additionally, A. palmatum will tolerate drier soils than A. circinatum.)

The Pacific Northwest Gardener's Book of Lists , R. & J. McNeilan, 1997, p. 18, 27, 30.
Tree & Shrub Gardening for Washington and Oregon , A. Beck & M. Binetti, 2001, p. 244-249.
Trees & Shrubs for Northwest Gardens , J. A. Grant & C. L. Grant, 1990, p. 56-58.

Date 2017-05-11
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Plant Answer Line Question

Keywords: Germination, Propagation, Acer

I am interested in the seed germination requirements of Acer triflorum and Acer griseum.


There is information in The Reference Manual of Woody Plant Propagation by Michael Dirr and Charles Heuser (Varsity Press,2006):

Acer triflorum seed is "doubly dormant and when fall planted will germinate the second spring and sporadically thereafter. Seed, unfortunately, is often not sound [...] Nine months warm followed by 3 months cold gave reasonable germination. If seed is received dry it may be prestratified for 6 months and then sown. Germination is less than 1% the first year but is very good the second."

The authors state that with Acer griseum, "the biggest problem is poor seed quality" (between 1 to 8% viability). Also, seed production from an individual tree varies widely from year to year. "Seeds are doubly dormant and if fall planted require 2 years, some germinating the third year and beyond. The pericarp wall is extremely tough and dormancy is caused by a physical barrier as well as internal embryo conditions." Dirr says that he has cold-stratified seed for 90 days, split the fruit wall to extract the embryos, and planted them in vermiculite with a fair amount of success. Growing this tree from cuttings is considered extremely difficult, and grafting (onto seedling Acer griseum seems to be the easiest propagation method.

Date 2017-02-25
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Plant Answer Line Question

Keywords: Plant diseases--Diagnosis, Master gardeners, Acer

I have an uncommon maple (Acer ukuruduense) that I planted two years ago, and which one year ago started sending out long stems from the base, so that now it has a vase shape. One month ago the main (original) stem turned black almost to the ground (the bottom two feet or so are still green), and all its leaves turned brown and fell off. Some of the buds still seem viable, but it seems to be dying at the tips. The rest of the plant is so far showing no signs of trouble. I have not been able to figure out what is going on.

1. What is causing this?
2. What, if anything, did I do wrong, and what can I do differently?
3. Might this problem spread to other trees: I have several other small maples in the vicinity.

Other information: The tree is so far just surrounded by bare dirt. This year I watered it frequently with a soaker hose throughout the summer, but last year I was not watering it regularly. It is in full sun, which it is supposed to like.


I am sorry to hear about your diseased maple. Your rare species was mentioned in 2 of our 3 books on maples. However, none of the books describe pests or diseases species by species. The books only give information on "general maple problems." The Gardener's Guide to Growing Maples by James Harris states that maples are "generally trouble-free," but the following can cause problems:
Verticillium wilt, which can kill a tree in a few days, or branch by branch over many years; it is a soil borne fungus that is quite common in Seattle (sorry);
Fusarium, which is another soil borne fungus;
Botrytis, which is a fungus, worst on seedlings, but can also cause die-back on established plants; this fungus favors warm humid conditions;
Die-back, which is not a disease; new growth in fall is not hardened off by winter-time and is killed by cold temperatures.

Take a sample branch into a Master Gardener clinic for a diagnosis (insist they submit it to the CUH diagnosticians if they do not know).

If it is Verticillium you can only slow down the disease by reducing all stress on the tree (keep it well watered and mulched). If your other maples are healthy and established they should be okay, but all are vulnerable to this nasty fungus.

Date 2017-06-09
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Plant Answer Line Question

Keywords: Verticillium, Plant diseases--Diagnosis, Acer

I want to test the roots of our Japanese Maple for Verticillium wilt. Are there places which could test for that?


There is information about Verticillium wilt and how to manage it on the Washington State University Extension's HortSense website.

To have a sample from your Japanese maple diagnosed, you can take samples to a free Master Gardener Clinic, or you can send samples (for a fee) to WSU Puyallup Research and Extension Center:
go to "How to Submit a Sample," scroll down to "Plant Problem Diagnosis," then you can download a form by clicking on "Form C1006."

My personal experience with this disease is that the Japanese maple lived with it for quite a few years before totally succumbing, at which point we had it removed by an arborist.

Date 2017-06-09
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Plant Answer Line Question

Keywords: Integrated pest management, Acer

I have a wood boring beetle in a maple tree and I am wondering if there is a treatment for the tree or do I need to take the tree down?


Here is a link to University of Kentucky's entomology department website that describes a number of different species of insect borers affecting trees and shrubs, including maples.

I also consulted Pests of Landscape Trees and Shrubs: an Integrated Pest Management Guide, second edition, which suggests that prevention is best. If you can make sure the tree is protected from damage, and prune any damaged limbs and branches (should be done when adult borers are not present, Fall through February), this should help, since the borers are attracted to stressed, damaged, or diseased trees. Do not store cut wood near the tree. Insecticide is not considered effective against borers under the bark. If the tunnels are visible and there are not too many of them, you can try using a sharp wire to probe and kill the larvae, but it may be difficult to tell how far to insert the wire.

If the infestation is not severe, you may be able to save the tree by improving its care and its growing environment.

Date 2018-03-15
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Plant Answer Line Question

Keywords: Limonium, Helichrysum, Skimmia, Elaeagnus, Echinops, Alstroemeria, Callicarpa, Calluna, Aster, Lavandula, Achillea, Quercus, Viburnum, Dahlia, Cotoneaster, Acer

My son and his sweetheart are planning a wedding in Seattle (my hometown) this coming September and would love to use seasonal flowers and greenery. I have not lived in the area for many years and am at a loss. Can you give us some suggestions please?


Here are some of the plants which are available in September: Achillea (Yarrow)
Alstroemeria (Peruvian lily)
Callicarpa bodinieri (beautyberry)
Cotoneaster (for foliage)
Elaeagnus (foliage)
Hebe (flowers and foliage)
Helichrysum (straw flower)
Acer (Maple: foliage)
Quercus (Oak: foliage)
Limonium (Statice)
Viburnum tinus

Here is a link to the Washington Park Arboretum web page of seasonal highlights.

A great book on flowers by season is A Year Full of Flowers: Fresh Ideas to Bring Flowers into Your Life Every Day by Jim McCann and Julie McCann Mulligan.

Date 2017-12-08
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Plant Answer Line Question

Keywords: maple syrup, Acer

I want to know what trees produce maple syrup, and if they'll grow in the Pacific Northwest. Also, will I be able to get syrup from them in our climate?


I believe that any of the syrup-producing maples will grow here, but syrup production might not be possible as it depends on specific weather conditions. University of Minnesota Extension has an article on the main species of maple used for syrup (including Acer saccharum, Acer rubrum, Acer saccharinum, and Acer negundo.

An article in Wikipedia describes the type of weather conditions needed for syrup production.
"Production is concentrated in February, March, and April, depending on local weather conditions. Freezing nights and warm days are needed to induce sap flows. The change in temperature from above to below freezing causes water uptake from the soil, and temperatures above freezing cause a stem pressure to develop, which, along with gravity, causes sap to flow out of tapholes or other wounds in the stem or branches."

Massachusetts Maple Producers Association describes temperature's effect on sap flow:
"Sap flow from sugar maples is entirely temperature dependent. A rise in temperature of the sapwood to above 32 degrees F. causes a positive pressure within the wood. This pressure produces the sap flow. Many people assume that maple sap flows up from the tree's roots on warm days. Actually, on warm spring days which follow cold nights, sap can flow down from the maple tree's branches and then out the spout. The sap can also flows back and forth laterally within the tree. It will flow out a hole drilled into the tree or out through a broken or cut branch. The internal pressure of the tree, when it is greater than the atmospheric pressure, causes the sap to flow out, much the same way blood flows out of a cut. If you visualize a portion of a tree trunk as being under positive pressure, a taphole is like a leak, sap moves towards the point of lowest pressure from all directions."

There is a tree description for Acer saccharum from the University of Washington's Campus Tree Tour:
"The chief attributes of this species are its major role as an important component of forests in much of eastern North America, its warm orange fall color, its highly useful wood, and its sweet sap. When the trees are leafless in late winter, their sap rises and descends with the temperature, and people extract it to use in making syrup or sugar, whose maple flavor is one of the unique delights of life. Our climate is too warm in winter for commercially worthwhile sap harvest, but the trees grow well here."

I think that our winters and early springs are not usually cold enough to be optimal for maple sugaring. However, I did find an archived article in Mother Earth News (1979) about tapping trees for syrup in the Pacific Northwest.

Date 2017-08-15
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May 23 2018 14:32:42