Weeds in Lawns & Gardens

Encyclopedia Article

trumpet creeper
Trumpet Creeper (Campsis radicans) growing as a weed in a perennial bed.

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.

Weeds in our lawns and gardens can be divided into two major groups, annuals and perennials. 

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 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. 

pokeweed
Pokeweed (Phytolacca decandra)

crabgrass
Crabgrass (Digitaria sanguinalis)

Weeds are also generally classified as broadleaf or grassy weeds.  While not all weeds can be classified within these two groups, many common garden and lawn weeds can be. Video Icon

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 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.

 

Weeds can also be classified by other characteristics based on how they grow.

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 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 Icon

 

Weed Identification

Thistle
Thistle in Garden Bed

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 descrptions of weeds commonly found across Iowa.

Direct links to select common weeds in lawns and gardens are below.

CrabgrassVideo Icon  -  Creeping Charlie  -  Dandelion  -  Giant FoxtailVideo Icon  -  Garlic MustardVideo Icon  -  Honeyvine Milkweed  -  LambsquartersVideo Icon  -  Nimblewill Yellow NutsedgeVideo Icon  -  Broadleaf Plantain  -  Poison IvyVideo Icon  -  Pokeweed  -  Prostrate Knotweed  -  Prostrate Spruge  -  Canada ThistleVideo Icon  -  Wild ParsnipVideo Icon  -  Wild Violet

 

How do I know if a plant is a weed or not?

 

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

Handpulling, Cultivation, & Digging

Managing through Cultural Practices (watering, tilling, etc.)

Mulches - in the Landscape & Garden Bedsin 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 - in the Landscape & Garden Bedsin the Vegetable Garden

Boiling Water

Flame Weeding

 

Managing Spefic Types of Weeds

honeysuckle
Honeysuckle (Lonicera)

Honeyvine
Honeyvine Milkweed (Cynachum laeve)

Annual Weeds (both broadleaf & grassy)

Perennial Broadleaf Weeds

Perennial Grassy Weeds

Woody Weeds

Vining Weeds

 

Managment of Select Common Lawn & Garden Weeds

Birdsfoot Trefoil

Black Medic

Crabgrass - in the Lawn - in the Garden Bed

Creeping CharlieVideo Icon

Duckweed

Moss

Nimblewill

White Clover

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

 

Last Reviewed: 
September, 2021
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