Weeds in Lawns & Gardens
Every garden has weeds and dealing with these unwanted plants is an ongoing task in any landscape. Control of weeds is important. Weeds are strong competitors for available water, nutrients, and sunlight. Reduced air circulation created by tall weeds encourages the development and spread of foliage diseases and a weedy garden often has more insect problems. While a completely weed-free garden is not attainable, reducing weeds is beneficial.
Keeping ahead of weeds and controlling them when they are small is essential for good weed management. This requires persistence throughout the entire growing season to remove weeds as they emerge.
Weed Classification
Weeds can be divided into several major groups. Some species can be classified in one or more of these groups, and others cannot be classified in any of these groups. Understanding how the weed is classified will help with control as the management of weeds in each respective group looks similar.
Annual Weeds
Annual weeds grow rapidly, flower, set seed, and die in a single season. New annual weeds, such as crabgrass, velvetleaf, purslane, knotweed, lambsquarter, and foxtail, germinate from seeds each year.
Perennial weeds
Perennial weeds die back to ground level in fall but send up new growth in spring. Perennial weeds, such as dandelion, quackgrass, thistle, pokeweed, and plantain, reproduce by seeds or may spread by creeping above or below ground stems or by spreading root systems.
Broadleaf weeds
Broadleaf weeds are those weed species with leaves that are wider and often have a major vein running down the center of the leaf with secondary veins branching off it. They are typically botanically classified as eudicots (dicots). Examples of broadleaf weeds include dandelion, thistle, pokeweed, knotweed, lambsquarter, purslane, plantain, violet, and creeping Charlie.
Grassy weeds
Grassy weeds have long thin leaves with parallel veins. They are often in the Poaceae (grass) family or a closely related family and are botanically classified as monocots. Examples of grassy weeds include crabgrass, foxtail, and quackgrass. [Video]
Woody weeds
Woody weeds are trees and shrubs that have woody plant tissue. They are perennial and typically classified as eudicots, although some may belong to other plant groups like gymnosperms (conifers). Examples of woody weeds include tree of heaven, bush honeysuckle, and poison ivy.
Vining weeds
Vining weeds are those that climb or vine by twining or by utilizing specialized structures like tendrils or aerial roots. They are often botanically classified as eudicots and can be woody or herbaceous, perennial or annual. Examples of vining weeds include poison ivy, honeyvine milkweed, bindweed, and trumpet creeper. [Video]
Weed Identification
Knowing what species of weed you are dealing with is important to understanding how to best control it.
Weeds in the same group or classification (such as annuals, broadleaf, etc.) are managed in very similar ways.
Information on Common Weeds This link includes photos and descriptions of weeds commonly found across Iowa.
Direct links to select common weeds in lawns and gardens are below.
- Crabgrass [Video]
- Creeping Charlie
- Dandelion
- Giant Foxtail [Video]
- Garlic Mustard [Video]
- Honeyvine Milkweed
- Lambsquarters [Video]
- Nimblewill
- Yellow Nutsedge [Video]
- Broadleaf Plantain
- Poison Hemlock
- Poison Ivy [Video]
- Pokeweed
- Prostrate Knotweed
- Prostrate Spurge
- Canada Thistle [Video]
- Wild Parsnip [Video]
- Wild Violet
Weed Management
Weed management requires persistence throughout the entire growing season removing weeds when they appear and preventing them from getting large, flowering, or setting seed.
There are many different techniques for weed management and effective control often comes from using a combination of different techniques.
Weed Management Techniques
- Hand pulling, Cultivation, & Digging
- Managing through Cultural Practices (watering, tilling, etc.)
- Mulches in the Landscape & Garden Beds | in the Vegetable Garden
- Mowing & Trimming
- Herbicides: Post-emergent in the Landscape & Garden Beds | in the Vegetable Garden | in the Lawn
- Herbicides: Preemergent
- Organic Weed Control Options
- Boiling Water
- Flame Weeding
Managing Specific Types of Weeds
- Annual Weeds (both broadleaf & grassy)
- Perennial Broadleaf Weeds
- Perennial Grassy Weeds
- Woody Weeds
- Vining Weeds
Management of Select Common Lawn & Garden Weeds
- Birdsfoot Trefoil
- Black Medic
- Crabgrass - in the Lawn - in the Garden Bed
- Creeping Charlie [Video] (both links for in the lawn)
- Duckweed
- Moss
- Nimblewill
- Poison Ivy
- White Clover
- Wild Parsnip
- Wild Violet
Publications & Other Links Related to Weed Management
- Weed Control in Home Lawns
- Weed Management in the Home Garden
- Weed Control - Gardening in the Zone Video
- Integrated Crop Management Weed Resources
- Integrated Crop Management Weed Management Videos
- Weed Identification Field Guide
- Aquatic Plant Management
- Weed Management for Organic Farmers
- Turfgrass Weed Control for Professionals
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on . The information contained within may not be the most current and accurate depending on when it is accessed.