• Matt Suprunowicz

How to Weed Your Garden


How can we eliminate unwanted competitors in the garden?


 

This Lesson Plan is part the Gardening Module of SustainEd Farms' virtual programming.

Background

The presence of weeds has been a problem for gardeners and farmers since humans began domesticating plants around 10,000 years ago. Weeds -- unwanted plants -- pose trouble in a variety of ways; namely, they compete with crops and other intentionally planted plants for nutrients, water, and space, and can be a hassle during the harvesting process. Many approaches have been taken to prevent weeds from establishing in the first place and to limit their numbers when they have taken hold. These methods vary in their effectiveness, scaling, and environmental impact, so they are often used in tandem with other methods. In this lesson, the student will explore some of these strategies while gaining additional insight into hand weeding a garden.


Learning Objectives

Students will be able to...

  • Identify weeds to hand weed their garden (thereby maximizing their crops’ productivity)

  • Understand different methods for weeding, and the pros and cons of each

Academic Vocabulary

herbicide /ˈ(h)ərbəˌsīd/ noun. - a substance used with the intention of killing a targeted plant or group of plants

till /til/ verb. - the act of preparing land for agricultural use through mechanical manipulation

weed /wēd/ noun. - any unwanted plant that is growing in the same space or nearby vicinity as an intentionally grown plant


Directions

1. Watch the following YouTube video to see a demonstration of how to weed a garden. Then, follow along with the remainder of the lesson by reading the steps below.


2. Before beginning weeding, it will be important to consider the pros and cons of several weeding strategies employed by gardeners and farmers all over the world. Consider the amount space you have and the spacing between any currently growing crops, the time of season, and what tools are available for your use.

​Weeding Method

Pros

Cons

Using herbicide

  • “Organic herbicides,” i.e. not synthetically produced herbicides, may not cause environmental degradation, making them an attractive option for eliminating weeds

  • Herbicides are often able to selectively eliminate plants, making their application easy with the proper tools

  • Many herbicides are and are thought to be environmentally degrading, though the effects of some may be secondary or tertiary effects (for example, effecting microbe activity within another organism)

  • Herbicide resistance can develop (plants that survive herbicide applications are selected for artificially), which then leads to higher rates of herbicide application and the acceleration of downstream environmental harms

  • Requires expensive machinery to apply over large swaths of land

Applying tillage (hoe, cultivator, shovel, etc.)

  • Kills living weeds by uprooting them or chopping them at root

  • If timed correctly (before weeds go to seed), can be very effective for small and large scale operations in the short term (immediate reductions in weed pressure for a quick reintroduction of a crop)

  • May disrupts and destroy soil aggregate structure and microbiome

  • Using heavy machinery can cause soil compaction

  • Causes water loss in the top layer of soil and increases potential for erosion

  • Requires expensive machinery to use on large plots of land

Burning

  • Flame weeding heats plant cells until they “burst,” inhibiting their ability to ingest nutrients and water

  • Ash mixes in with soil with little effect

  • Releases carbon dioxide into atmosphere

  • Can be somewhat dangerous, especially when used in dry conditions

  • Can accidentally set fire to crops

  • Plants may regrow

  • Fuel costs

  • Environmental impacts of fuel

Mowing

  • Cuts plants at surface, thereby limiting or eliminating any possible soil disruption

  • If done before weeds go to seed, the residual plant matter can decompose and add to organic content

  • Can act as a mulch to suppress weed development

  • ​Plants may regrow

  • May spread more weed seed if done at an improper time

  • May require expensive machinery

Mulching

  • A surface covering layer of organic matter (straw, shredded wood, leaves, etc.) that can stop the growth of weeds by blocking out light

  • Improves the soil in a multitude of other ways, including improving moisture retention, increasing light reflectance or absorbance (depending on the color of the mulch; absorbing will keep it warm, while reflecting will keep it cool), reducing erosion, and adding organic content to the soil

  • Can require a lot of time to spread effectively

  • If done improperly, can cause rotting on crops and inhibit their root growth

  • Some mulch may contain weed seeds

Smothering with covers

  • Weed mats/covers will deprive plants of photosynthetic requirements (light) to grow

  • Covers produce greenhouse effect (trapping thermal radiation) at plant surface that can cause disruptions for growing weeds while keeping established plants warm

  • Application of plastic coverings may be time intensive and wasteful

  • Can be ineffective at eliminating weeds

Animal grazing

  • Feeding weeds to animals serves as a dual purpose function

  • Animals provide manure to the land in addition to eliminating weeds

  • Cost effective

  • Animals may eat or damage crops, possibly limiting the frame they are able to graze on weeds

  • Grazing habits of certain animals may not eliminate weeds completely

Hand Weeding

  • Allows the entire plant to be removed with minimal disruption to the soil or crop roots

  • Probably most precise method of weeding

  • Very time intensive and labor intensive

Using native species

  • Native species of plants may be able to compete better with weeds than crops can

  • Introduces natural benefits (beneficial insects, microclimate generation, soil biodiversity, etc.) of incorporating surrounding ecosystem into farm or garden

  • Waiting for native species to establish may be time costly

Rotating crops

  • A well thought out succession of crops can eliminate weed pressure with a variety of competitive forces that hinder the continual establishment of weeds (varying soil structure and availability of nutrients)

  • Some crops can compete directly with weeds, which makes them attractive in a rotation

  • N/A

3. To hand weed a garden space, you must identify unwanted plants in the area. There are a few scenarios to consider here: 1) if you have a cover crop, 2) if you have other crops growing, and 3) if you have nothing growing other than weeds. If there are plants other than weeds, then a great deal of care must be taken to avoid pulling crops from the ground. Ideally, and under any of these circumstances, you should have a good understanding of what your “wanted” plants look like or will look like. Take ample time to look at pictures of seedlings of different types of crops you decide to plant. Finally, it will be important to identify weeds before they have gone to seed in order to save you time from weeding in the future.


4. Kneeling by the identified plant, gently brush aside any material sitting at the base of the plant, and grab the weed by the stem where it meets the ground. Yank the plant from the ground, turning and twisting slowly if need be. Keep a tight grip when pulling -- the goal is to remove all of the plant’s roots from the soil to prevent any existing shoots from regrowing. If the plant breaks before removing completely, tug at any remaining parts. Use a trowel, if necessary, to take the entire plant out of the ground.


5. Dispose of the weeds in a compost bin if they haven’t gone to seed; if they have gone to seed, you may just throw them away as working them into your compost may spike your weed pressure, if applied.


6. Repeat for all of the weeds in your garden!


Additional Resources:

Download the PDF version of this lesson plan:

How to Weed Your Garden
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