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Elisabeth C. Miller Library

Keyword: Native plant gardening

Garden Tip #430

The pollinators need our help. Not just because humanity’s food supply relies on pollinators, but because invertebrates are the backbone of a healthy ecosystem. Concerned gardeners will find guidance and an action plan in The Pollinator victory garden: win the war on pollinator decline with ecological gardening: how to attract and support bees, beetles, butterflies, bats, and other pollinators by Kim Eierman (2020).

Eierman’s Tips for a Pollinator Victory Garden

  • Don’t use pesticides of any kind, including organic; and avoid buying nursery plants treated with “neonics.” A quality nursery should be able to tell you whether their plants have been treated with this systemic pesticide.
  • Create over-wintering habitat by leaving some fallen leaf litter on the ground. Soil organisms will also appreciate the leaf litter.
  • Create growing season habitat for solitary, ground-nesting native bees by leaving a sunny, sandy patch of soil free of mulch. Then watch out for little mounds with a hole in the center, kind of like a tiny volcano, for evidence of a bee making a nest for her larvae.
  • Native pollinators prefer native plants, and some rely exclusively on native plants. Eierman compiled a list of plants for the Pacific Northwest on her website, Ecobeneficial.com.

Eierman makes the case for pollinators

Native plant resources

I’m looking for a good publication on plant communities for my
area, Whatcom County in northwest Washington. We want to encourage plant communities that will do well here, and have about 5 acres to work with. Can you make a suggestion, please?

 

If you are interested in
plants native to Washington, I recommend these two books:

Kruckeberg, Arthur R., Gardening with Native Plants of the Pacific
Northwest, University of Washington Press, Seattle, 2nd edition, 1996.

Pettinger, April, and Brenda Costano, Native Plants in the Coastal Garden – A
Guide for Gardeners in the Pacific Northwest , Timber Press, Portland, OR,
revised edition, 2002.

The Washington Native Plant Society is also a good resource.

If you are interested in plants that will grow well in your area, but are
not necessarily native to Washington State, please check out the Miller Library’s
booklist about gardening in the Pacific Northwest.

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mulching Pacific Northwest native plants

Is is good to mulch Arctostaphylos uva-ursi? If so, would an aged bark be best or a mulch that contains manure? How deep should the mulch be?

Native Plants in the Coastal Garden (by April Pettinger, 2002, p. 27), says the following about mulching Pacific Northwest native plants:
“…When an established native plant garden requires maintenance, it is usually minimal: mulching is probably the most important—and often the only—maintenance required. In any garden, mulching is arguably the most beneficial care you can give your soil and your plants. There are many advantages to using mulch. It suppresses weeds, conserves moisture by minimizing evaporation, and releases nutrients to the soil…Good mulch materials are compost, decaying leaves, well-rotted manures, sea kelp, mushroom compost, seedless hay or straw, shredded prunings, natural wood chips, grass clippings and evergreen needles and cones. Commercially available screened bark—usually referred to as bark mulch—has little to offer other than its ability to conserve water; it has no nutritional value and in fact depletes the nitrogen in the soil. When spreading mulch, don’t pile it too close to stems of plants. If you are using compost as mulch, spread it about 2 to 4 inches deep. Other materials may be applied to a depth of 3 to 7 inches…”

butterfly conservation in the Pacific Northwest

I have become interested in helping with the conservation of monarch butterflies, whose caterpillars feed only on milkweed. We are supposed to plant milkweed. I am also gradually converting my small Seattle garden to a native-plant garden. Do these two goals contradict each other? Are any of the milkweeds native to Seattle and vicinity? Would monarchs themselves be an exotic species here?

It’s wonderful that you want to help with butterfly conservation. Monarch butterflies are not frequently seen in the Puget Sound region and, as you may be aware, it is too cold for them to overwinter here (they need an air temperature of at least 50 degrees Fahrenheit, according to Jerry Sedenko’s The Butterfly Garden [Villard Books, 1991]). However, you can do several things to make your home landscape hospitable to the pollinators we do have in our area, including not using any pesticides in your garden and persuading your friends and neighbors to refrain from using them also.

The Monarch Joint Venture project links to the Xerces Society’s Milkweeds: A Conservation Practitioner’s Guide which has information on milkweed species and their natural habitats. The plants recommended by the MJV for the West are Asclepias speciosa and Asclepias fascicularis but these plants may not be successful in the Puget Sound region. Both species are found mostly east of the Cascades as these maps from the USDA show. (click on the detail maps for Washington State)

The Xerces Society for Invertebrate Conservation has useful information(now archived) about Western Monarchs, as well as separate pollinator conservation resources (for different types of pollinators–not Monarchs) for the Pacific Northwest.

You might be most effective in supporting the Monarch conservation effort financially but devoting your gardening efforts to conservation of species that are native to our area. Here are the Xerces Society’s list of Pacific Northwest butterflies and bees.

The Puget Sound Beekeepers Association has information on bee-friendly gardening.

The issue of using native plants in our urban gardens is a complex one. How do we define the native status of a plant? Sometimes the only plants available in nurseries are cultivated varieties of native species: are they still ‘native?’ Are plants that have naturalized in our area native? Do we have the ideal conditions in our garden to sustain native plants?

My personal outlook on this is that it’s best not to think too rigidly about what is native and what is not, but instead to be vigilant about what is overly aggressive or definitively noxious and invasive, and to try to grow a diverse range of plants that will thrive without excessive watering, fertilizing, and fuss, and select plants (native and otherwise) will attract birds, beneficial insects, and local species of butterfly. Here is Washington State University Extension horticulturist Linda Chalker-Scott’s essay on the topic of native plants.

Trumpet Vine and vines that attract hummingbirds

I live in Bellevue and was thinking of planting a couple of Trumpet vines against a very tall wood fence in my yard (Campsis radicans). I found quite a lot of messages online about these plants being very invasive. Do you know that to be true for this area? If so, what other plants could I use against the fence and which attract hummingbirds as the Trumpet Vine claims to do.

Campsis radicans (trumpet vine) is not considered officially invasive in the Pacific Northwest, though it may be an aggressive grower that needs (or takes up) a fair amount of space. If you do decide to look for alternative vines to grow, scarlet runner bean is attractive to hummingbirds, as are honeysuckle (harder to grow than Campsis as it has occasional problems with aphids), and clematis, according to Naturescaping, published by the Oregon Department of Fish and Wildlife (2001).

The local website of Rainyside Gardeners has a list of nectar plants for Northwest hummingbirds. Of the plants on this list (which includes Campsis radicans, Honeysuckle(Lonicera), and Scarlet runner bean), Eccremocarpus scaber, Ipomoea, Jasminum stephanense, Mina lobata, and Tropaeolum are all vines, some of which are annual.

King County Natural Resources has a searchable native plant guide, and here are the native plants they recommend for hummingbirds:

  • Tree:
    • Madrone; madrona (Arbutus menziesii)
  • Vine:
    • Orange honeysuckle (Lonicera ciliosa)
  • Shrub:
    • Red-flowering currant (Ribes sanguineum)
    • Black gooseberry (Ribes lacustre)
  • Groundcover:
    • Thrift; sea pink (Armeria maritima)
    • Western columbine (Aquilegia formosa)
    • Cooley’s hedge nettle (Stachys cooleyae)

In my own garden, the Italian Jasmine (Jasminum humile, a shrub grown against a wall, not a vine) appeals to hummingbirds, and in the fall they seem to like the Camellia sasanqua.

on Cistus x purpureus and Nandina domestica

My landscaper has planted several Cistus marked Cistus x purpurea. He said it was a solid colored [pink/lavender] flower without spots at the base of petals. I have spent hours searching for a photo, all photos that refer to purpurea are spotted. They also are
referred to as orchid rock rose. Once there was a picture of a unspotted shrub, referred to as Cistus and next to it was a spotted one that had the purpurea label. Can you shed some light?

Also planted is Nandina domestica “Royal Princess.” There is hardly any information available on my search for this. It appears to be pretty, but I did read that outside of Seattle, some nurseries on the west coast stopped selling it. Should I anticipate a problem with this plant ? I also read that in some eastern states Nandina domestica is invasive.

 

Here is what I found on the web page of the Royal Horticultural Society.
The correct name is Cistus x purpureus. It has deep pink flowers with burgundy blotches at the base of the petals.

The Cistus website (a British site), in addition to its gallery of pictures of different species of Cistus, has some information about misnamed plants, which may be what you and your landscaper encountered.

Here is information from The National Gardening Association about Nandina domestica ‘Royal Princess.’

Here is an excerpt from San Marcos Growers site:

Nandina domestica ‘Royal Princess’ (Heavenly Bamboo) – This is an upright growing shrub to 6 to 8 feet tall has very lacy foliage. Pinkish white flowers bloom in clusters at the ends of branches in the late spring and summer followed by a heavy set of red berries ( notably heavier than most Nandina cultivars). The foliage turns to burgundy in spring and later a orange-red in fall. Branching stands stiffly upright unlike typical Nandina domestica and the foliage has a much finer texture. Plant in sun or shade. Tolerates fairly dry conditions but looks better when given water occasionally. It is hardy to about 10 degrees F.

Nandina is widely grown in our area, and so far has not exhibited the
invasive properties it has in the Southern U.S. Several cultivars are
listed on the Great Plant Picks website, which is created by local
gardening experts, so I am assuming there should not be a problem with
growing it here. If you are still concerned about it, the main way it
becomes invasive is from the berries setting seed and spreading. You
could plant native ornamentals in its place, if you wish. Here are links
to information about native plant landscaping:

Washington Native Plant Society
PlantNative.org
King County’s Native Plant Guide

Northwest Native Plant Landscape Guide

King County’s Natural Resources and Parks department has made it easy for gardeners to include native plants in their gardens. The site includes garden design plans for sun or shade, dry or wet sites; detailed plant profiles that may be searched by name or browsed by photos; and a collection of short articles on topics such as proper site preparation. The most useful feature is the ability to create customized plant lists that can be printed, emailed or even saved for a later visit.

PlantNative.com

“Dedicated to moving native plants and naturescaping into mainstream landscaping practices.” Includes a how-to for creating a native plant landscape and directories by state for native plant nurseries, regional plants and community service organizations.

Pacific Northwest Native Plant Habitat Garden Manual

Pacific Northwest Native plant habitat garden manual cover
“Pacific Northwest Native Plant Habitat Garden Manual” is a short, loose-leaf bound notebook intended to give the basics for teachers and students establishing school gardens using natives.

Excerpted from the Fall 2010 Arboretum Bulletin.