Elisabeth C. Miller Library

Gardening Answers Knowledgebase

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Recently Added Questions

Question:

I have a large Western Red Cedar (Thuja plicata, I think!) under which grow a few weeds but not much else. I would like to find a low maintenance solution for the ground that won't do any harm to it. Ground cover? Pea gravel? I worry that the shallow root system can be easily smothered so that adding soil and plants is not a good idea, plus the roots are a dense mat and difficult to dig through. Do you have any ideas or suggestions? What native plants might grow under the tree and how can I get them established?

Answer:

As you've realized, Western red cedars have a dense mat of roots close to the surface. It's not a good idea to add soil on top of the roots of trees because their root flare should remain above the soil -- and even if you did, the roots of cedars would spread into that soil in a short period of time. It's also important to keep in mind that under natural conditions the ground beneath Thuja plicata is usually bare of other plants.

If the area beneath your tree isn't in deep shade and has at least some sun, you could plant spring ephemerals, including bulbs. They emerge in spring when the soil has plenty of moisture, then most die back before our summer droughts. They're not difficult to plant under large trees because you don't need to dig a large hole for seeds, bulbs, or small bare-root perennials. Good choices are Anemone blanda, Aquilegia (Columbine), Corydalis lutea, Crocus, Galanthus (snowdrops), Iris reticulata, and various kinds of Narcissus, including daffodils. Most tulips are not long-lived in our area. Hardy Cyclamen emerge and flower at other times of the year, but they're also an excellent choice. Unfortunately, most of these plants are summer-dormant, when you'll probably be out in your garden, and some self-seed prolifically under ideal conditions. A valuable resource, available for checkout at the Miller Library, is Planting the Dry Shade Garden, by Graham Rice (2011). Some of the plants he recommends will require regular watering under cedars.

Another option, also feasible if your area has some sun, is to plant our native Western sword fern (Polystichum munitum). It's evergreen, so has a presence all year, and is the most sun and drought tolerant of our native ferns. I have a 60 foot red cedar in my garden, and have successfully maintained sword ferns beneath it in partly sunny areas, but not in deep shade, where they've died out. However, because they won't survive our summer droughts in nature under these conditions, I've needed to water them about every 3 weeks in order to keep them alive. I've planted fairly small plants and watered them more often than that during their first year. If your soil is very sandy, sword ferns might not do well.

If you require a reliably showy solution, staging large planters planted with annuals or perennials, shrubs and/or trees might be best. The plants you choose will depend upon how much sun the area receives. Of course, they'll need to be watered regularly, but large planters don't need watering as often as small ones. If your hose-bib is not too far away, installing drip irrigation on a timer will ensure that your plants survive when you're away from home.

Question:

I had a fig tree that fell over due to fast growth after prolonged heavy rains. Some of the wood has been saved, and is seasoning, for possible use in smoking meats and/or conditioning of home-brewed beer. Are there potential toxins I should be concerned about? What flavors and/or aromas might I expect?

Answer:

None other than the New York Times has an article by Florence Fabricant (May 23, 2001) about the aromatic properties of fig wood (including using it to flavor meats):
Excerpt:
"Chefs love hardwoods for grilling. Fig wood, which burns hot and fast and sends a heady, almost sweetly floral aroma into the air, is the latest one gaining their favor."

Pascal Baudar's book, The Wildcrafting Brewer (Chelsea Green Publishing, 2018), has a section on the use of bark and wood in making beer. He suggests using wood chips, toasted and added to fermenting beer (or soda, or mead). Fig is among the woods he recommends for its "mild and nutty qualities." (Other wood chips he mentions as worthy additions are manzanita, maple, mesquite, olive, white ash, and yellow birch).

The only toxicity I can think of would be the sap (latex) that is in the leaves, stems, and unripe fruit, and can cause skin irritation. Here is additional information from Purdue University's New Crop Resource Online.

Question:

I'm looking for detailed information on how well Pacific wax myrtle (Morella aka Myrica californica) performs in northwestern Washington. Also, when is the best time to prune this shrub for renovation?

Answer:

Morella californica is native to the Pacific Northwest (including the southern part of the Washington coast), and is generally recommended for planting in our area. It's very fast-growing during the first 10 years after planting, and is tolerant of drought, wind, and salt spray. It's also tolerant of varying soil conditions, and takes well to pruning.

However, during the past decade, it's been found to be susceptible to a leaf-blight disease, Phytophthora taxon morella. Many Phytophthora species are primarily root-rot diseases, but this one is a foliar disease. It's important to remove affected growth and clean up fallen leaves. New leaves produced in late fall and winter are very susceptible, so pruning should be done in spring. Infections tend to fall off as the weather warms. In the past, California wax myrtle was considered both sun and shade-tolerant, but plants growing in shady conditions are more susceptible to this disease than plants growing in open conditions.

Question:

Is the California foothill pine the same as a digger pine? Will it grow in the Pacific Northwest?

Answer:

Foothill pine is a more acceptable common name for Pinus sabiniana. It is also referred to as gray pine, or ghost pine and, less commonly, see-through pine (because of its open, lacy structure). The name 'digger pine' originated during the California Gold Rush of the nineteenth century, when prospectors noticed Native Americans foraging (‘digging’) for pine nuts, roots, and bulbs. The gold-diggers referred to the native people as Digger Indians, a term that is now considered derogatory. James Hickman, editor of The Jepson Manual: Higher Plants of California (University of California Press), made a point of referring to the tree as foothill pine or gray pine, including a note asking people not to use the pejorative name: "I think this is better than not mentioning the issue at all." In Sandra Strike’s Ethnobotany of the California Indians (Koeltz, 1994), the author says that Native Americans used a digging stick to forage bulbs and roots "without disturbing other plants. Natives were appalled when they saw the large holes and destruction caused by non-natives' 'modern' digging tools. Many California Natives prefer that Pinus sabiniana be called 'Gray Pine.'" The large cones of this pine were important as a food source, with seeds rich in oil and protein.

According to Arthur Lee Jacobson's Trees of Seattle (2006), this three-needled pine with substantial cones, somewhat sparse, gray-tinted, and weeping foliage, is rare in Seattle. There are specimens in the Washington Park Arboretum, UW campus, the Chittenden Locks, and Rodgers Park. Because of its native range (which is mostly hot, dry, and rocky), the main thing you might want to consider is whether you can provide a site that has excellent drainage and warmth. In California, it is often found in growing near Ceanothus cuneatus and native oaks.

Question:

What type of plant is the mistletoe people refer to during the holiday season? How did it get its name?

Answer:

There are over 1,000 mistletoe species. It is a parasitic plant that was hosted by the oak tree, but also seen on pear trees in Roman times. Mistletoe has a long history of ritual use, myth, legend, and folklore. The name 'mistletoe' comes from two Anglo-Saxon words: mistle, meaning dung, and tan meaning twig. Why "dung on a twig," you might ask. The name comes from the way the plant is propagated by birds eating the berries, then passing the seeds through the gut, and excreting the deposits onto the branches of trees. Seeds are rubbed around by the birds' beaks when they wipe them on the bark. The seeds then germinate from cracks in the twigs of the tree. The species of European lore and legend is Viscum album, which lives on deciduous tree species, such as apple and poplar. In North America, mistletoe more commonly refers to Phoradendron leucarpum. You can watch a clip of birds interacting with an Australian mistletoe species on the BBC's website. We also have in the library a copy of The Private Life of Plants by David Attenborough, which describes the phenomenon.

If you want to go deeper into the lore, we also recommend checking out The Green Mantle: An Investigation into our Lost Knowledge of Plants by Michael Jordan.