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

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

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

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.