Annuals that sprout in fall and winter and then flower in the spring are cool season annuals. The photo shows common groundsel (Senecio vulgaris) in a dry creek bed landscape feature. The seeds float on air currents to new locations.

Annuals that sprout in spring when the soil warms and flower in the summer and fall are warm season annuals. The photo shows crabgrass (Digitaria spp.) growing in a brick patio.

Shiny geranium (Geranium lucidum) is an annual plant that grows 6–18 inches tall. It forms dense mounds that smother other vegetation. It often grows in landscapes and along roads, trails, and forest edges. Shiny geranium is an invasive plant species. Take action to control it.

Wild carrot (Daucus carota) is also known as Queen Anne’s lace. Wild carrot plants grow a rosette in their first year. In the second year, they form long stems with white flower heads (umbels) at the tips as shown in the photo. Wild carrot attracts bees and other pollinators. It provides significant food resources for them.

Tansy ragwort (Senecio jacobaea) is a biennial, non-woody (herbaceous) plant with yellow flowers. Tansy ragwort forms dense stands. It crowds out other herbaceous plants. All plant parts are toxic to people. Tansy ragwort is poisonous to some livestock.

Common burdock (Arctium minus) is a herbaceous, biennial weed. It often grows along roadsides and abandoned fields. The photo shows a burdrock rosette. The leaves are up to 20 inches long and 12 inches wide and heart shaped. In the second year, burdock grows a stem up to 5 feet tall and forms purple flowers and fruits with hooked bristles. The bristles stick to clothing and animal fur, which aids in seed dispersal.

Dandelion (Taraxacum officinale) is a common perennial weed. It has a long taproot that anchors it in the soil. You should dig and remove dandelion plants by the root. But they may regrow from small pieces of root broken off deep in the soil, so keep an eye on problem areas.

Canada thistle (Cirsium arvense) is a perennial and spread by seeds and robust underground root systems. Mow stems several times per year to keep it from spreading. The seeds travel via wind to new locations. Until you remove the roots, it will keep coming back each year.

Field bindweed (Convolvulus arvensis) has extensive root systems deep underground. New vines emerge from roots when old vines are removed. Keep bindweed from climbing up plants and fences by removing new vines as they emerge.

Quackgass (Elymus repens) is an invasive perennial grass. It grows up to 4 feet tall from seeds and creeping roots (rhizomes). It becomes a problem in landscape beds and other areas that are not often tilled. Quackgrass forms dense stands that suppresses crop growth. It out-competes native species in natural areas.

Small patches of quackgrass and other herbaceous perennial weeds can be covered with a light-impenetrable barrier.

Heavy equipment is useful to dig out large perennial grasses such as jubatagrass and pampasgrass (Cortaderia jubata and C. selloana).

Invasive blackberry (Rubus armeniacus) is a widespread invasive plant that grows throughout the Pacific Northwest. It thrives in a variety of habitats. Blackberry spreads quickly and is difficult to control. Dig it out by the roots. Watch for regrowth and control it as needed.

Broom species (Cytisus spp. and other species) are evergreen shrubs with bright yellow flowers. Following control activities, look for broom regrowth and seedlings. Control them as needed.

Tree-of-heaven (Ailanthus altissima) is an invasive tree that spreads quickly and is difficult to control. It thrives in abandoned sites. Roots must be killed or tree-of-heaven grows back. Controlling tree-of-heaven without herbicides is very challenging. Return to areas where you control it. Expect to re-treat for two or more years.

The photo shows summer annual weeds between kale plants. The weeds need to be removed with hand tools at this stage to keep them from overcrowding the kale.

Dig out dandelion and other herbaceous weeds by the root to kill plants.

Remove all parts of the plant when hand-pulling weeds. Dispose of weeds in yard waste or compost.

The photo shows vegetable transplants, a hoe, and newly germinated weeds on bare soil. Cultivate the soil surface when weeds are small. Gently scrape the weed seedlings with a sharp cultivating tool. Repeat as needed until the canopy of your desired plants shades the soil to suppress weed growth.

Use power tillers to cultivate the surface of the soil to kill young, small weeds. These tools don’t work well for large weeds. However, tillers damage soil structure and bring new weed seeds to the surface.

The photo shows a worker using a flame weeder to kill weeds in a path in a farm field.

Flame weeders kill young weeds such as the ones shown in the photo. Flame weeders work best for broadleaf weeds (dicots). They are less effective for grasses (monocots).

Dig out the root crown of woody perennial weeds. Use picks, shovels, or similar tools. A selection of tools for removing woody plants is shown in the photo.

Manual removal of woody shrubs and small trees is effective but labor intensive. Using a Weed Wrench™ or similar tool makes it easier to remove larger shrubs. 

String trimmers with a blade attachment cut thickets of blackberry and other woody perennial plants. A tractor-mounted flail mower attachment effectively shreds blackberry canes.

After blackberry or woody perennials have been mowed, the plants will often regrow. The photo shows blackberry regrowth one month after mowing in the late spring. Further action is needed to control this patch of blackberry.

Use a tractor-mounted disk harrow to control grasses and broadleaf weeds. Disking at the right time kills annual weeds. Disk after germination before plants flower. Perennial weeds like Canada thistle will regrow after disturbance. Control regrowth as needed to prevent plants from setting seed.

Carefully timed mowing limits weed seed production. After mowing, many plants will regrow and try to flower again. Repeat mowing and consider other control methods to keep weeds from setting seed.

Use heavy equipment to pull or dig isolated bushes. Remove as much of the root system as possible.

Repeated grazing is a good way to suppress plant growth. It is often followed up with other control methods.

Contact professional pest control companies with experience grazing goats to control weeds. Or ask your Soil and Water Conservation District office for referrals.

Take the time to remove weeds in landscape beds before you plant. Before planting, dig out perennial weeds such as blackberry, dandelion, bindweed, or creeping buttercup. Remove the entire root system. Look for regrowth and follow up as needed.

The photo shows weeds growing in compost. Use weed-free topsoil and compost products, and nursery plants. Don’t bring new weeds to your site.

Use edging to separate your lawn from landscape beds. Edging is attractive and helps to prevent grass from lawns from growing into landscape areas.

The best way to keep weeds out of your lawn is to grow thick, healthy turf. Provide lawns with water and nutrition. Apply seed over the top of your lawn at least every other year. The photo shows a seed spreader with lawn seeds on an established lawn area.

Keep weeds from producing seed to minimize future weed problems. A single pigweed plant such as the one shown in the photo can produce 100,000 or more seeds. The seeds remain viable in the soil for many years.

Don’t bring weed seeds that are on equipment or clothing to your site. The photo shows weed seeds attached to the worker’s boot and leg. Clean your shoes, clothing, and tools to keep from bringing new weeds onto your site.

A dense cover of low-growing plants prevents weeds from growing.

Cover up bare soil in landscape areas with vegetation. The desired plants will shade the soil and keep weeds out.

Wood chips are an effective mulch choice for use in landscapes. Wood chips are often available for free. Ask tree care companies working in your neighborhood if they can drop off a load of chips for you.

Carbon-rich mulch such as wood chips, bark dust, and straw helps to suppress weed seed germination. Mulch helps to conserve water. As it decays, it improves the soil structure over time. The photo shows bark mulch in a landscaped area.The look of this mulch appeals to many people.

Compost is best used as an amendment that is mixed into the soil before planting. When compost is used as a mulch, weeds germinate and grow as shown in the photo. Carbon-rich mulch such as wood chips, bark dust, and straw are less likely to allow weeds to grow.

Weed barriers (landscape fabrics) are applied under mulch. Weed barriers shade the soil and help to keep weed seeds from germinating. Add new mulch on top of the weed barrier every 1–2 years to keep the fabric buried. But weed seeds may germinate in the mulch. The roots then grow through the fabric. The fabric may tear when weeds are removed. Also, shifting mulch exposes the fabric over time, as shown in the photo.

Use plastic mulch for annual plantings such as vegetables. Plastic mulch warms the soil as well as limits weed growth. Use thick black plastic sheeting from the hardware store. Or source biodegradable plastic from specialty grower supply stores. Plastic mulch is not recommended for permanent plantings.

Rock mulch is not recommended as an effective method to suppress weeds. Weeds that become established are hard to remove. Rocks increase surface temperature. Dry stream bed landscape features use rock mulch. Put landscape fabric under the layer of rocks. You will need to remove weeds regularly to keep dry stream beds weed-free.

The sheet mulching method uses a layer of cardboard or newspaper as a temporary barrier placed on the soil surface. Then place a 3–4 inch deep layer of organic mulch such as leaves or compost on top of the cardboard. The cardboard layer breaks down over time. This method works to keep weed seeds from germinating temporarily. It doesn’t work to keep perennial weeds from growing.

Use opaque plastic sheeting or a tarp to shade out weeds before preparing soil for planting. If you are planning to expand your garden or landscape, cover the area for 3–6 months with an opaque barrier. The barrier will keep annual weed seeds from germinating. The barrier deprives perennial weeds of light and weakens them.

Soil solarization uses clear plastic secured to the soil surface to heat the soil and kill weed seeds and other pests. Follow these steps: Cultivate and rake smooth. Water to 8-inch depth. Cover the soil tightly with clear plastic for 4–6 weeks during mid-summer. Remove plastic. Avoid disturbing the soil at this time.

The photo shows white fertilizer at the base of a perennial landscape plant. Place fertilizer in the root zone of desired plants to promote robust growth and help keep weeds from growing.

The photo shows drip irrigation tubing and emitters next to a landscape plant. Drip irrigation is an effective way to water desired plants. It minimizes water application between desired plants and this helps to keep weeds from growing.

Sprinklers are an effective way to provide water for your plants. However, using overhead sprinklers to apply water to bare ground encourages weeds to germinate and grow.

Provide your desired plants with the sunlight they need to grow. A dense canopy of desired plants shades out weed seedlings.