Kill your lawn
Author: Dave Tomashefski
Below are a few common methods for converting lawn to garden beds. These can be used whether you will be planting seeds or plants.
Method 1: Sheet mulching
You can plant almost immediately. Takes lots of cardboard.
When to use it
- In sun or shade.
- When grass is actively growing.
- If starting a garden from seed, use a fine mulch (like leaf compost) and wait a few months until the cardboard has broken down.
Supplies
- Cardboard or newspaper.
- Hose and running water.
- Mulch. Leaf compost is optimal: it’s loose and light, which means it’s easy for ground-nesting bees to move aside.
- (Optional) A manual or mechanical bed edger can be used to create a well-defined border.
Instructions
- Mow grass (optional, but makes it easier to cover grass where cardboard overlaps).
- Use bed edger to define border, if desired.
- Cover with layer of unwaxed cardboard or, alternatively, newspaper > 10 sheets thick.
- Wet the cardboard or newspaper.
- Cover with approximately 4” of mulch.
- When desired, cut holes in cardboard to plant plants. Leave a 2” gap between the mulch and the base of the plant to avoid rot.
Pros
- Can be planted immediately (unless starting a garden from seed).
- Can be used in sunny or shady areas
- No soil disturbance / weed seed stimulation.
- No soil loss.
- Uses biodegradable materials.
- No chemical toxicity.
- Can be used in sunny or shady areas.
Cons
- May not kill perennial weeds such as Canada thistle and field bindweed.
- Requires a lot of cardboard.
Method 2: Smothering
Good use of a tarp. Takes at least 2 months.
When to use it
- In sun or shade
- When grass is actively growing.
- Takes 2 months to kill grass, an entire growing season to kill most perennial weeds (e.g., white clover), and 2 or 3 growing seasons to kill some perennial weeds (e.g., Canada thistle and field bindweed).
- Be patient if starting a garden from seed. Starting with a completely clean slate is especially important in this case.
Supplies
- Tarp.
- Greenhouse repair tape.
- Stakes or rocks to hold tarp in place.
Instructions
- Mow area (optional, but may result in less plant debris when tarp is removed).
- Cover with dark, impermeable tarp, or other material such as plywood. Secure with rocks or stakes.
- Leave in place for at least 2 months.
- Promptly patch or mend with tape any holes that develop in the plastic. Greenhouse repair tape works best.
Pros
- Can be used in sunny or shady areas.
- No soil disturbance / weed seed stimulation.
- No soil loss.
- No chemical toxicity.
Cons
- Takes a long time to kill some perennial weeds such as Canada thistle and field bindweed.
- Tarp is non-biodegradable.
Method 3: Solarization
Kills deep weed seeds in full sun. Takes time, setup is labor intensive.
When to use it
- Full sun areas, i.e. areas receiving at least 6 hours of direct sunlight per day.
- For 2-4 months, which must include July and August (i.e., the hottest months of the year).
- Be patient if starting a garden from seed. Starting with a completely clean slate is especially important in this case.
Supplies
- Lawnmower
- Hose and running water
- Clear, UV resistant plastic sheeting, 4 or 6 mil thickness. (can be bought from Home Depot).
- Greenhouse repair tape. 3M brand clear repair tape sold at Home Depot.
- Shovel for burying edges of plastic. A flat-edged shovel works best.
Instructions
- Remove sticks, rocks, and debris from area.
- Mow grass very short.
- Optional: rototilling may increase effectiveness of solarization.
- Thoroughly wet area.
- On following day, cover with sheet of clear plastic. Recommended plastic thickness is 4 or 6 mil.
- Plastic should not be loose or wrinkled.
- Secure plastic around perimeter of area by burying edges at least 4” deep.
- Promptly mend any holes in plastic, preferably within 24 hours. Use greenhouse repair tape.
Pros
- Kills weed seeds in top 2 – 6” of soil.
- No chemical toxicity.
- No soil loss.
Cons
- Only works in sunny areas.
- May not be effective on weeds with roots extending deeper than 2-6”.
- Creates plastic waste.
Method 4: Rototilling
Quick results in turf with low weed pressure.
When to use it
- Flat areas (sloping areas are susceptible to erosion).
- Soils that are not overly rocky.
- When grass / weeds are actively growing. This will allow assessment of new weed germination post-rototilling.
- Be patient if starting a garden from seed. Starting with a completely clean slate is especially important in this case.
Supplies
- Lawn mower.
- Hose and running water.
- Rear-tine rototiller (this is a heavy duty rototiller suitable for grass removal).
- Rake
- Hoe
- (Optional) A manual or mechanical bed edger can be used to create a well-defined border.
Instructions
- Mow very short.
- Clear area of sticks, rocks, and other debris.
- Thoroughly water the area and let the water soak in / dry for 24 h. The target soil consistency is soft and crumbly but not muddy.
- Till to a depth of approximately 6” using a rear-tine rototiller. Make sure soil is thoroughly churned and all clods and grass clumps are broken up.
- Use bed edger to define border, if desired
- Rake up and remove exposed plant roots.
- Wait 2 weeks to assess weed germination. Remove newly germinated weeds with hoe or by hand. Repeat as necessary until weed germination subsides.
Pros
- No soil loss (assuming no erosion).
- Equally effective in sun and shade.
- Little waiting, depending on extent of weed germination.
- No chemical toxicity.
- No plastic waste.
Cons
- Exposure of bare soil stimulates weed germination.
- Weeds with roots extending deeper than 6” will likely re-sprout.
- May cause erosion on sloping land.
Method 5: Sod-cutter
Quick results in turf with low weed pressure. Lose precious soil.
When to use it
- Soils that are not overly rocky.
- When grass / weeds are actively growing. This will allow assessment of new weed germination post sod-cutting.
- Be patient if starting a garden from seed. Starting with a completely clean slate is especially important in this case.
Supplies
- Lawnmower
- Hose and running water.
- Sod-cutter.
- (Optional) A manual or mechanical bed edger can be used to create a well-defined border.
Instructions
- Mow area very short. This will make it easier to roll up / move the cut sod.
- Thoroughly water lawn. Allow to soak in / dry for 1-3 days.
- Operate sod-cutter at appropriate depth. Grass as well as roots should be removed. The most common depth is 1.5”.
- Roll up and remove the sod strips, exposing the bare soil underneath.
- Use bed edger to define border, if desired.
- Wait 2 weeks to assess weed germination. Remove newly germinated weeds with hoe or by hand. Repeat as necessary until weed germination subsides.
Pros
- Equally effective in sun or shade.
- Little waiting, depending on extent of weed germination.
- No chemical toxicity.
- No plastic waste.
Cons
- Topsoil loss.
- Will not kill weeds whose roots are deeper than operating depth, e.g., 1.5”.
- Exposure of fresh, bare soil may stimulate germination of weed seeds.
Method 6: Herbicide
Effective on large areas. Be aware of unintended effects.
When to use it
- When grass is actively growing.
- Special consideration is needed near waterways (see note below)
- Repeat applications may be necessary in areas with heavy weed pressure.
Supplies
- Lawnmower.
- Roundup Ready to Use Weed and Grass Killer with Sure-shot Wand.
- Note: if applying near a waterway or pond, use AquaNeat and follow instructions on label.
- Turf Mark Spray Indicator.
Instructions
- Mow area.
- Use 2% glyphosate solution containing surfactant and blue dye. Easiest technique is to use Roundup Ready to Use Weed and Grass Killer with Sure-shot Wand, and add 2 oz. of Turf Mark Spray Indicator (i.e., blue dye) to 1.33 gallon container.
- For best results, apply on sunny day when temperature is greater than 60 F. Do not apply on windy day due to risk of drift.
- Thoroughly spray area.
- Two weeks later, spray one more time.
- Wait 3 days before planting.
- Cover dead vegetation with 2” of leaf mulch, if desired.
Safety
- Wear eye protection and disposable latex gloves.
- Wash hands and forearms after use.
- Keep area free of pets and foot traffic for 4 hours or until herbicide has dried.
Pros
- Kills weeds down to the root.
- Effective in sun or shade.
- Does not disrupt soil / stimulate weed seed germination.
- Minimal plastic waste.
- Minimal waiting.
Cons
- The Xerces Society reports that exposure to glyphosate can disrupt bee navigation and impair their gut bacteria, thereby increasing the bees’ susceptibility to pathogens.