I am trying to select plants for a green roof on Lopez Island. I would like to use some native plants, and not have to do too much weeding. Can you help me?
The Miller Library has a booklist on green roofs which includes weblinks. With respect to weeds, as a former professional gardener I don’t believe there is a “maintenance-free” garden. However you may be able to come up with a freely seeding grass (Festuca ovina var. glauca comes to mind) that would do well and look good with other plants.
Regarding Pacific Northwest native plants (i.e., grasses), I recommend using a native plant book (such as Pojar and MacKinnon’s Plants of the Pacific Northwest Coast) and searching for those which suit the conditions of the site. You may also find King County’s native plant
guide useful, as it is searchable by site requirements. Washington Native Plant Society offers a similar plant selection guide. There are also native species of Sedum.
The book Green Roof–a Case Study by Christian Werthmann (Princeton Architectural Press, 2007) evaluates green roof plants and planting techniques, and includes observations regarding soil depth, the factors affecting desiccation (i.e., metal edging and the planting medium/size of the plants used), and density considerations. Here are some of the conclusions of the case study:
- p.69-insects and other invertebrates need >6″ of soil to survive the cold;
drought tolerance increases with soil depth; probability of seed germination also increases with soil depth
- p.76-erosion control (bird repellant?) made from a degradable straw mat (such a mat may be useful for preventing birds from pulling up the plugs)
- Plants:
p.95-sweet fern Comptonia peregrine-not too vigorous, suffered from weed infestations
p.96-prickly pear Opuntia fragilis-did well
Phlox subulata, Silene caroliniana-did well
Sedum telephioides, S. lanceolatum, S. stenopetalum-suffered from heat, drought, and birds-these were replaced with European sedums (S. album, S. reflexum, S. spurium, S. cauticola, S. sexangulare, S. floriferum, Sempervivum tectorum, Orostachys boehmeri) and not planted as plugs but as larger plants that started in the green roof substrate (reducing transplant shock)
p.100-mixed prairie perennials with sedums (in 6″ soil), which filled in when perennials died-the architects note that there is no record of prairie plants doing well on green roofs, therefore the backup with succulents-they also note that metal roof edges speed up desiccationPerennials included ice plant (Delosperma nubigenum; my note: be careful about this, as it’s a noxious weed in California and if it spreads by seed, it might become a problem on Lopez); flameflower (Talinum calycinum); Eragrostis spectabilis; Allium schoenoprasum; Allium cernuum; Bouteloua gracilis; Elymus virginicus; Achillea millefolium; Tradescantia bracteata; Solidago nemoralis; Artemisia ludoviciana; Coreopsis verticillata; Asclepias tuberosa; Rudbeckia hirta
p.105-in 3″ soil with nearby metal (and thus an overheating issue), they used proven sedum species; heat from metal can be reduced by using aluminum (proved cooler than wood)
p. 108-conclusions: use a combination of indigenous plants with “successful green roof performers”-thin soil and high light “even overtaxed the hardiest succulents”-soil depth and temperature extremes made a big difference; even a slight difference in soil depth in a harsh environment can mean the difference between success and failure-continuous care and maintenance in the beginning is important for success-plugs grown in peat moss were less successful, since completely dried-out peat moss repels water-dense plantings (and/or rapidly spreading plants) important because bare soil gets hotter than soil covered by a plant.
I’ve never done any canning before but now that I’ve started growing more of my own fruit and vegetables I want to know how to do it safely! I’ve heard about a few different canning processes (water bath and pressure). Is one method or another best for certain types of food?
There is a very helpful article for canning beginners in the July/August 2012 issue of Urban Farm magazine, entitled “Oh, You Know I Can!” by Lindsay Evans. You mention the only two canning methods which the article says are approved by the U.S. Department of Agriculture as safe, water-bath and pressure canning. Their National Center for Home Food Preservation has extensive information. Here are excerpts:
Proper canning practices include:
- carefully selecting and washing fresh food,
- peeling some fresh foods,
- hot packing many foods,
- adding acids (lemon juice or vinegar) to some foods,
- using acceptable jars and self-sealing lids,
- processing jars in a boiling-water or pressure canner for the correct period of time.
Methods that are NOT recommended are open-kettle and steam canning, or using the oven or microwave to process filled jars.
The article has a handy list of which foods work best with water-bath canning, and which with pressure canning. Generally, high acid foods (pH level of 4.6 or less) can be processed with the water-bath method and low acid foods (pH of 4.6 or more) must be canned using pressure. High acid foods include apples, apricots and other stone fruit, berries, cherries, lemons, pears, tomatoes, pickles and sauerkraut. Low acid foods include asparagus, beets, carrots, corn, green beans, lima beans, rutabagas, and turnips.
Here is a link to more canning information from the National Center for Home Food Preservation.
I have a young 5-foot tall Hollywood juniper. How do I prune it to shape and train it so it looks good?
Because of the natural beauty of its form, Hollywood juniper, or Juniperus chinensis ‘Torulosa’, is not a good candidate for pruning, and I would recommend only pruning branches which are interfering in some way, such as intruding into a walkway. Below are links to information on pruning junipers:
University of Georgia Extension
Excerpt:
“Junipers do not tolerate heavy pruning because of the lack of new growth on old wood. This makes it important to know the growth habit of a particular juniper prior to planting so that future pruning can be minimized. Junipers can be tip pruned and thinned, but not cut back to large limbs. Pruning out old. dead foliage underneath creeping junipers will often contribute to better air circulation and thus better health of the plant.”
University of Florida Extension
Excerpt:
“Torulosa Juniper develops into a showcase specimen without pruning and is probably best used for this purpose.”
In her Guide to Pruning (Sasquatch Books, 2006), local pruning expert Cass Turnbull advises strongly against shearing and cutting into old wood, because you will be looking at woody stubs for a long time, if not forever. You can remove lower limbs which may be blocking sidewalks, but in general, avoid pruning. “Junipers, like most conifers, are difficult to prune. This is because the barren portions of the branches can’t produce new greenery (break bud) once the exterior green has been removed (headed back). Never expose those ugly, barren internal branches . . . What little can be done to help an overgrown planting involves removal of the lowest limbs, and/or selective heading (grab and snip) or thinning off the worst, most interfering branches. Always hide the cut beneath some natural-looking greenery.”
Your young plant should shape and train itself without the intervention of pruning.
Where can I find a list of foreign nursery catalogs?
We have many foreign nursery catalogs at the Miller Library, as well as a list of what we have. Call us at 206-543-0415 or 206-897-5268 (every day but Sunday) and we can fax you the list. Or stop by and look at the catalogs. Library hours and directions to get here can be found here.
In addition, the Royal Horticultural Society has a plant finder online. Go to this link and follow the instructions. You can either search by plant or by nursery (name, region, or specialty).
The commercial website Dave’s Garden has a section on mail-order gardening and nursery catalogs, including some foreign ones.
This summer, I have been picking Himalayan blackberries in a local schoolyard. Twice in the last month, I developed sharp pains in my hand immediately afterward. There must be some type of neurotoxin in the bushes because the pain cannot be attributed to any cuts or scratches and is much more intense than a standard rash. What part of the plant could cause that reaction?
I checked Botanical Dermatology (Mitchell & Rook, 1979), Plants That Poison (Schmutz, 1979), the Plants for A Future database, and Toxic Plants of North America (Burrows/Tyrl, 2001) and found no references to any toxicity. Medical Botany: Plants Affecting Human Health (Lewis, 2003) describes the use of a blackberry-leaf tea for settling the stomach, so the leaves, when steeped, are not toxic. You do not say whether the pain is superficial, such as a skin rash, or deeper, which would make me wonder about some kind of stress or overuse syndrome.
Since we cannot give medical advice, you should discuss the incident with your health practitioner to see if you have some sensitivity to Himalayan blackberry, or to something else you encountered in that area. I found this link (to a page called Native Plants of Montara Mountain) showing the similarity in appearance between Himalayan blackberry and poison oak. It might be that you encountered poison oak without knowing it.
It may be that some other environmental factor (perhaps an application of herbicide) caused your distress. You should check with the school’s grounds supervisor to be certain.
I am looking to install wine-producing grapes in my back yard, but I want to purchase vines from a reputable company, especially since I want to minimize the chance of exposure to Phylloxera. Where would you recommend I shop for the 12-20 vines I would like to install in my back yard?
While I cannot guarantee that any of these nurseries sell stock that is free of Phylloxera, here are three reputable nurseries that may have what you are looking for:
Raintree Nursery
Burnt Ridge Nursery & Orchards
Cloud Mountain Farm
Source: Susan Hill. The Pacific Northwest Plant Locator 2000-2001.
If you would like to know more about Phylloxera, Oregon State University’s booklet, Grape Phylloxera: Biology and Management in the Pacific Northwest discusses the subject in great detail.
I have a grapevine that is totally out of control and growing from the arbor into the trees. How and when should it be pruned back? I cut one vine that was up in the tree and it seemed to “bleed water.”
From the American Horticultural Society Pruning and Training Manual, ed. by C. Brickell (1996, p. 289.):
“Prune only in midwinter when the risk of sap bleeding from cuts is at a minimum; any later, and bleeding may be difficult to stop (cauterization with a red-hot poker is the traditional remedy).”
From the book The Grape Grower, by L. Rombough (2002, p. 44-45.):
“Pruning Neglected or Overgrown Vines…If the trunk of the vine is straight, or is otherwise healthy, you may be able to short-cut the process by cutting everything back to the head of the trunk. You will have no crop that season, but you can easily train the new shoots that emerge as canes or new cordons to bear a full crop the following year. More often, the vine will be such a mess of old growth and oversized wood combined with twisted, multiple trunks that the simplest way to prune it is with one quick cut, through the base of the trunk(s), right at ground level. Kill the vine? No! Almost without fail, the vine will bounce back and refill the arbor or trellis in one season, because it has the full vigor of a large, established root system behind the new growth. The newly regrown vine should resume full production the very next year.”
Is the California foothill pine the same as a digger pine? Will it grow in the Pacific Northwest?
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.
What type of plant is the mistletoe people refer to during the holiday season? How did it get its name?
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.
Can you tell me the name of all those shrubs with tiny purple marble-like fruit that grow along the walkway by the Intramural Activities building at University of Washington? Are they related to pepper? They look like purple peppercorns! Are they edible?
This shrub, which goes mostly unnoticed until its dramatic fruit stands out in fall, is Callicarpa (beautyberry), most likely Callicarpa bodinieri var. giraldii ‘Profusion.’ Based on the size and shape of the fruit, I can see why you might think this plant could be related to pepper (the seasoning). Taxonomists have moved beautyberry around, but for now Callicarpa is in the mint family, Lamiaceae, while pepper (Piper) is in Piperaceae, and requires a warmer climate (subtropics or hotter) than ours.
Callicarpa is not listed in any of the usual sources on seriously toxic plants, but that does not mean its fruit is safe or tasty for human consumption. According to Julia Morton, a botanist and author of Wild Plants for Survival in South Florida, “the rank odor of the plant makes nibbling of beautyberry bunches on the stem unpleasant.” This article from the Cape Coral Daily Breeze (February 6, 2015) mentions that birds, deer, and squirrels enjoy the fruit. In my own garden, it is not the first choice of birds, but I have seen them trying it from time to time. Humans find the fruit mealy and insipid, according to the article, but that doesn’t stop avid foragers from attempting to make jelly from it.
If you grow Callicarpa, you may learn to appreciate its subtle flowers in spring, and the gently turning colors of its leaves in fall. Callicarpa americana also has terpenoids in its leaves that repel insects (mosquitoes, ticks, ants, and more).