According to the Royal Horticultural Society Encyclopedia of Garden Plants (1996, p. 753), Parrotia persica needs acid soil for best autumn color. If yours is at the top of a slope, our heavy rains may have leached much of the acid content. Take a soil test to determine the pH level. Products containing aluminum sulfate, sulphur or ferrous sulfate (sold to make hydrangea flowers blue) will acidify the soil, but artificially altering soil pH will require constant maintenance.

Season Fall
Date 2007-12-06
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I am finding some conflicting information about what Katsura trees like. Most references say moist but well-drained soil, but one source says deep, permanently moist soil and very sensitive to drought. Another says adequate moisture especially when young. Yet another says water during dry periods. There is a Katsura planted in the Arboretum on the edge of a pond in soil that is permanently wet and it is doing just fine. So what to do.

Step 1 - take some dead branches or stems to a Master Gardener clinic and ask them to help you identify what could be happening.

Step2 - check that the compost is not closer than 4 inches from the trunk of the trees. If it is, scrape it away.

Step 3 - take a soil sample from around the tree and send it to a lab for analysis. Our website has a Soil Testing Information section that includes a list of labs that do soil test analysis.

Step 4 - check the area for drainage by digging a hole and filling it with water or let the rain do it and then see how long it takes to drain away. Perhaps you have a layer of hardpan clay underneath the trees that is blocking the drainage in winter and preventing the water from getting to the roots in summer.

Season All Season
Date 2007-12-13
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The Natural Lawn & Garden Hotline, sponsored by Seattle Public Utilities, provides the following recommendations on how to take a soil sample:
1) Take about 10 vertical slices of soil from the top 6-8 inches of your garden bed. If there is an area that you suspect to have problems, test this soil separately.
2) Place soil slices in a plastic bag and mix thoroughly. You are getting the average of the soil in your garden bed.
3) Take 1 cup from this mixture and dry it at room temperature. Do not dry in oven, on radiator or in microwave!
4) Put dry soil sample into a Ziploc bag and seal.
5) Label the outside of the Ziploc bag.
6) Mail to one of the soil testing labs below with completed order form and payment.

For a list of labs and consultants providing services in the Northwest, go to: http://wsprs.wsu.edu/AnalyticalLabsEB1578E.pdf

Another option is the University of Massachusetts Cooperative Extension Soil Testing.
See their soil testing brochure at: http://www.umass.edu/plsoils/soiltest/soilbrochdec2003.pdf.

The Soil and Plant Laboratory has offices around the country, including Bellevue, WA and Portland, OR.

For testing of toxics see: http://www.metrokc.gov/health/hazard/residenttesting.htm.

A & L Western Laboratories, Inc. in Portland, OR can provide soil and plant analysis.

Season All Season
Date 2008-01-24
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The first thing you might consider doing is having your soil tested. There are various labs that can test for toxins as well as for soil type and nutrient deficits etc. Here is a link to a WSU site, which lists the labs and what they do.

Here is some general soil info from the University of Vermont on soil but most recommendations for raised beds suggest double digging into the native soil which you may not want to do.

PREPARING THE RAISED BED AND PLANTER
Soil preparation is the key to successful gardening. To grow close together, plants must have adequate nutrients and water. Providing extra synthetic fertilizers and irrigation will help, but there is no substitute for deep, fertile soil, high in organic matter. As raised ground beds are only 8-10" deep, double-digging the beds will give best results. This is a very strenuous task and may require volunteer or paid labor. Remove the top twelve inches of soil from the bed. Insert a spade or spading fork into the next 10"-12" of soil and wiggle the handle back and forth to break up compacted layers, repeat this motion every 6"-8" in the bed. Mix the topsoil with a generous amount of compost or manure, and return the mixture to the bed. It will be fluffy and several inches higher than ground level. To raise the bed to 8 to 10 inches, take topsoil from neighboring pathways and mix it in as well.

For containers, elevated beds, and deep raised beds, a fairly lightweight soil mix is needed. Soil straight from the garden usually cannot be used because it is too heavy and does not allow proper drainage. Clay soil consists of extremely small (microscopic) particles. In a container, the bad qualities of clay are exaggerated. It holds too much moisture when wet, resulting in too little air for the roots, and it pulls away from the sides of the container when dry. The container medium must be porous in order to support plant growth since roots require both air and water. Packaged potting soil available at local garden centers is relatively lightweight and may make a good container medium if it is not too high in organic matter. Soilless mixes such as a peat-perlite mix are generally too light for container vegetable gardening, not offering enough physical support to plant roots. If the container is also lightweight, a strong wind can blow plants over, resulting in major damage. Soilless mixes are sterile, thus insect, disease, and weed free. How- ever, no trace elements are available for good plant growth and must be added. For a large container garden the expense of pre-packaged or soilless mixes may be quite high. Try mixing your own soil with one part peat moss, one part garden loam, and one part clean coarse builder's sand, and a slow release fertilizer according to container size. Lime may also be needed to bring the pH to around 6.5. A soil test is helpful in determining nutrient and pH needs, just as in a larger garden. Deep raised beds can be filled 1/3 to 1/2 full of broken concrete and stones to reduce the volume of soil required.

Season All Season
Date 2008-01-31
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Prunus lusitanica tolerates a wide variety of pH and moisture levels in soils. See California Department of Forestry Selectree webpage about this plant.

According to the webpage of a local Seattle garden writer, the leaves do change color slightly, acquiring a bluish tinge in late fall to winter. She also says that Prunus lusitanica does not like wet feet.

What colors are the leaves turning? You might consider testing the soil, to make sure things are not out of balance. Here is a link to a WSU resource explaining how to have your soil tested.

Is it possible that the bagged manure was still hot, that is, not fully aged? If so, that could cause problems.

You might also bring in photographs or sample leaves to a Master Gardener Clinic for diagnosis. You can locate a Master Gardener Clinic within Washington State at this website.

Season Summer
Date 2006-12-08
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Saline soil may have a high pH, a characteristic shared with soils which are alkaline. You may find this information on soils and pH useful:

Diagnosing Saline and Sodic Soil Problems

Soil Acidity and Liming (Overview)

Plant Materials for Saline-Alkaline Soils

Soil pH: What it Means

• Alkaline soil: A soil whose reaction is greater than pH 7.
• Acid soil: A soil whose reaction is less than pH 7.
• Saline soil has a pH less than 8.5.

Saline soil, as defined in Soils: An Introduction, by Michael Singer and Donald Munns (Prentice Hall, 1999): Saline soils ...contain large amounts of soluble salts, appreciably more soluble than calcium sulfate. Most commonly, these are salts of Na, Ca, and Mg, with chloride, sulfate, and bicarbonate...soils are considered saline if their electrical conductivity exceeds 4 deciSiemens meter-1. Many plants suffer at this level.

Application of fertilizers containing ammonium or urea speeds up the rate at which acidity develops. The decomposition of organic matter also adds to soil acidity.

Season All Season
Date 2007-04-04
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Your question about the safety of compost made from plant matter grown in a railroad-tie bed is complex. Railroad ties are treated with wood preservative that contains arsenic. Arsenic never goes away entirely, but the amount may be at lower levels than Washington State's law on clean-up, based on parts-per-million. I would definitely recommend a soil test. Here is information from the Northwest Coalition for Alternatives to Pesticides, which has a page on chromated copper arsenate.
The Center for Disease Control has published a Public Health Statement on arsenic, excerpted below:
"About 90% of all arsenic produced is used as a preservative for wood to make it resistant to rotting and decay. The preservative is copper chromated arsenate (CCA) and the treated wood is referred to as 'pressure-treated.'
Arsenic cannot be destroyed in the environment. It can only change its form, or become attached to or separated from particles. It may change its form by reacting with oxygen or other molecules present in air, water, or soil, or by the action of bacteria that live in soil or sediment. Arsenic released from power plants and other combustion processes is usually attached to very small particles. Arsenic contained in wind-borne soil is generally found in larger particles. These particles settle to the ground or are washed out of the air by rain. Arsenic that is attached to very small particles may stay in the air for many days and travel long distances. Many common arsenic compounds can dissolve in water. Thus, arsenic can get into lakes, rivers, or underground water by dissolving in rain or snow or through the discharge of industrial wastes. Some of the arsenic will stick to particles in the water or sediment on the bottom of lakes or rivers, and some will be carried along by the water. Ultimately, most arsenic ends up in the soil or sediment. Although some fish and shellfish take in arsenic, which may build up in tissues, most of this arsenic is in an organic form called arsenobetaine (commonly called 'fish arsenic') that is much less harmful."

Washington State University has information on gardening on arsenic- or lead-affected soil which may be of interest to you.

To be cautious, you should keep the compost from these beds separate from your other compost, and only use it on your ornamental plants already being grown in those beds. I don't recommend putting even slightly arsenic-contaminated yard waste into the city compost, since that means the problem is being spread farther afield. It would be worthwhile testing every so often for soil contaminants. Here is King County Public Health's guide on arsenic, and testing information.

Season All Season
Date 2009-03-28
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