Proper weed identification is essential for determining the best method of weed control. Weed identification books are helpful but there are so many choices that selecting the proper weed may be difficult. It is easier to identify the weed to the weed family and narrow the choices. Most weed books have weeds arranged according to their family. The below key will narrow the choices making weed identification much easier.
WSU Extension also provides a weed identification service (website) where your specimens may be identified by a professional taxonomist or weed science Extension specialist. There is no charge.
Attacking Annual Cheatgrass at its Roots; a short article about work in Eastern Washington to use a bacteria to inhibit cheatgrass root development.
Forb Seedling Identification Guide for the Inland Northwest Native, Introduced, Invasive and Noxious Species by Natural Resources Conservation Service, Washington. This guide was created to enable land managers to distinguish preferred seedlings from weed seedlings, and determine the success of a planting at an early stage. Species described in this guide are forbs planted in conservation plantings and common weeds in the Inland Northwest region.
Short introductory article by Susan Ballinger about shrub-steppe, We Can Help Keep Nature in Balance.
Invasive Weeds of Eastern Washington , WSU Extension Manual EM 005. Illustrated Field Guide to 32 common weed species in Eastern Washington, search able by flower color, common name, and growth characteristics.
Weed ID Photo Cards for 51 common weeds of Washington. Washington Native Plant Society.
Cultivating awareness, understanding, and stewardship of the Wenatchee River region.
Washington State Noxious Weed Control Board. ‘Noxious weed’ is the traditional, legal term for any invasive, non-native plant that threatens agricultural crops, local ecosystems or fish and wildlife habitat. The term ‘noxious weeds’ includes non-native grasses, flowering plants, shrubs and trees. It also includes aquatic plants that invade wetlands, rivers, lakes and shorelines.About half of all invasive, noxious weeds are escapees from gardens; the rest are plants accidentally introduced to Washington through human travel and trade. Resources include Weed Identification guides.
Chelan County Noxious Weed Board. Information about identification, management, bio-control with services for landowners.
While these weeds are tenacious, the conditions they thrive in can be changed. Start by adding a healthy helping of compost, such as Gardner & Bloome Soil Building Conditioner. Use mulch or cover crops to protect the soil in the winter, and try to hold off on working the soil in spring until it’s dry enough to crumble rather than forming large clumps. Plants with deep tap roots can also help naturally break up compacted soils over time.
Here are six common Pacific Northwest weeds that carry hidden messages about the soil.
As with compacted soil, amending with compost is the best way to lighten up clay soil. If the problem area is a lawn, don’t despair. As with all lawn problems, the best prevention is thick, healthy, consistently fed grass. Rehabilitate the area by pulling out the dandelions, aerating, and starting a consistent maintenance program, including top-dressing with compost and fertilizer each year.
In the meantime, garden-friendly bees love clover flowers, and these weeds actually add a bit of nitrogen to the soil as they grow. Bacteria that live in specialized nodes on clover roots essentially pull nitrogen out of the air and “fix” it into a form that plants can use. For this and other reasons, some people even choose to use clover as a convenient, low-maintenance lawn alternative.
Most weeds are pretty adaptable, so don’t leap to conclusions about your soil based on just one species. But when you see several kinds of weeds that prefer a certain habitat growing together, you might be on to something. Combined with a few other simple soil indicators, paying close attention to your weeds can tell you quite a bit.
Weeds can tell you a lot about your soil conditions, so don’t pull the messengers! At least not before you hear what they have to say.
Just like the ornamental plants you’d probably prefer to grow, many weeds have strong habitat preferences. Understanding why particular weeds are thriving can help you correct underlying soil problems or identify ideal ornamental plants for your conditions.
Not to be confused with the tropical banana-relative by the same name, this weedy groundcover thrives in the naturally “sour” soils that are common in this region. Other signs of acidic soil include moss predominating over grass, and other weeds like prostrate knotweed.
None of this will completely eradicate a bindweed problem, but it should give you and your more desirable plants a competitive edge.
Adding dolomite lime each year as part of overall good soil care will “sweeten” the soil and help make up for the leeching effect of heavy winter rains. You can also work with the existing conditions by planting acid-lovers like hydrangeas (which will bloom blue in acidic soils), rhododendrons, and blueberries.
The best way to deal with horsetail is often to work with it rather than against it. While it looks odd in a traditional flower bed, the fern-like foliage is actually quite beautiful combined with other wetland plants like spirea, willow, red-twig dogwood, and iris. If you allow your natural wetland areas to thrive, they can attract all sorts of birds and other wildlife.
Often called morning glory, the invasive weeds Convolvulus and Calystegia typically have white flowers. A non-invasive cousin of these garden pests that goes by the same common name, the ornamental Ipomea, typically has blue or purple flowers. Bindweed indicates compacted conditions and a hard soil crust, especially when found with quackgrass.
Another common lawn weed, clover, indicates soil that is low in nitrogen. Symbiotic bacteria provide clover with most of the nitrogen it needs, allowing it to thrive in nutrient-poor soils where lawn grass struggles. Good lawn care, including a consistent fertilizing schedule, will encourage grass and discourage clover.
As for managing chickweed, it does grow quickly, but it’s easy to pull out of the loose, healthy soil it prefers. True to its name, chickweed is a favorite treat for backyard chickens, and it’s packed with nutrients. Some adventurous gardeners even choose to eat it themselves.
Horsetail can be very frustrating for gardeners who don’t like the looks of it. It’s nearly impossible to eradicate. But this ancient native plant has good news for wildlife gardeners: it means your garden contains valuable wetland habitat. Dock and buttercup are also weedy wetland indicators. Even if the soil isn’t wet at all times of year, these weeds indicate a unique ecosystem that many animals call home.
While many weeds thrive in conditions hostile to more delicate plants, chickweed is typically found in previously-cultivated soil that is rich with organic matter and nutrients. If you find a lush stand of it growing along with healthy lamb’s quarters, that’s the place to build your new vegetable bed for heavy feeders like tomatoes. Don’t forget to continue feeding the soil to keep it in great condition year after year.
Many people don’t realize how often lawns need to be fed. We recommend using an organic lawn fertilizer three to four times each year. An easy way to remember the schedule is to feed your lawn on Valentine’s Day, Memorial Day, Labor Day & Thanksgiving. If you can’t fertilize that often, the most important dates are fall and early spring.
There’s a reason dandelion is so ubiquitous here in the Pacific Northwest: it loves our heavy clay soils. Although this adaptable weed can grow in many conditions, a thriving dandelion population in the midst of a struggling lawn likely indicates clay. Although difficult to completely eradicate, dandelion is a surprisingly useful weed, and it can be managed with proper soil care.
The plant-whisperers at Sky Nursery are happy to help decipher the hidden messages of your garden and lawn weeds. Just bring in a few good pictures or a sample, and we’ll help you understand the deeper causes of your weed problems and the best solutions for your particular situation. Understanding what your weeds have to say will help you improve your soil and work with the conditions you have to cultivate a thriving garden.