How To Plant A Raised Garden Over Grass? | No-Dig Fast Start

You can set a sturdy bed right on a lawn and start growing the same week. The trick is to smother turf, bring in a balanced mix, and water well from day one. This guide lays out the steps, the soil recipe, and the small details that keep roots happy all season.

Build A Raised Bed On Lawn — Step-By-Step Plan

Tools And Materials

Gather a tape measure, level, shovel, box cutter, wheelbarrow, rake, and hose with a spray head. For the frame, use rot-resistant boards (cedar, larch, or plain pine if budget rules). Exterior screws hold better than nails. You’ll also want plain corrugated cardboard without glossy ink or tape, plus soil and compost.

Pick The Spot

Choose a place with 6–8 hours of direct sun for fruiting crops. Near a water source is best. Keep the bed well away from large tree roots that will compete for moisture. A size of 3–4 feet wide lets you reach the middle without stepping in; length is up to you.

Smother The Turf (No-Dig Base)

Mow the grass as low as your mower allows. Lay overlapping sheets of cardboard where the bed will sit, covering past the footprint by 6–8 inches so creeping rhizomes don’t sneak in. Wet the cardboard until it’s evenly soaked; this helps it conform to the ground and begin breaking down, while blocking light that feeds regrowth. Research on sheet mulching with cardboard backs this approach for weed suppression and soil building. Sheet-mulching with cardboard covers the why and how in plain terms.

Assemble The Frame

Set your pre-cut boards on the wet cardboard. Check squareness by comparing diagonal measurements; equal diagonals mean the rectangle is true. Screw the corners tight. If the site is out of level, sink one side slightly or shim the low side so water doesn’t pool at an end.

Fill With A Balanced Mix

A dependable blend is about half topsoil and half plant-based compost, tweaked for texture. Loam or sandy loam drains well; heavy clay topsoil can be lightened with a modest share of coarse sand. University guidance points to a range near one-third to one-half compost with the rest topsoil for raised beds. See UMN raised bed guidance for ratios, watering, and material notes.

Level, Water, And Settle

After filling, rake the surface flat. Water until moisture seeps from the bottom edge; this settles air pockets. Top up with more mix if the level drops. A 10–12 inch soil depth grows most herbs, greens, and bush beans; tall crops and root veg appreciate a full 12 inches or more.

Bed Size And Soil Volume Planner

Use this quick planner to order the right amount. Volume is inside dimensions only. Round up a little to account for settling.

Bed Size (L × W × H)	Volume (cu ft / cu yd)	Approx. 1.5-cu-ft Bags
4 ft × 4 ft × 10 in	13.3 / 0.49	9
3 ft × 6 ft × 12 in	18.0 / 0.67	12
2 ft × 8 ft × 10 in	13.3 / 0.49	9
4 ft × 8 ft × 12 in	32.0 / 1.19	22
4 ft × 10 ft × 12 in	40.0 / 1.48	27

Soil Mix That Feeds And Drains

Simple Recipe

Blend 2 parts screened topsoil with 1–2 parts mature, plant-based compost. If your topsoil skews heavy, fold in a small share of coarse sand or a bagged aeration material such as perlite. The goal is a crumbly texture that holds moisture but doesn’t stay soggy. University sources caution against loading beds with all compost; it dries fast between waterings and can cause nutrient imbalance when used alone. The UMN page above lays out that balance along with watering notes.

Layering Works Too

Building tall beds and want to stretch your budget? Under the top 8–12 inches of the growing layer, you can add a base of sticks, chopped leaves, and extra compost in thin lifts. Expect to top up each season as those materials settle and break down. UMN outlines this “lasagna-style” alternative and notes that you’ll keep adding soil over time.

What To Avoid

Skip plastic sheeting under the bed; roots want to reach subsoil, and plastic can trap water. Cardboard is fine at the start, then it softens and allows infiltration. UMN also notes that permanent barriers can stunt roots and suggests removing any tarps before placing the frame.

Planting Day: From First Trowel To Last Label

Pre-Wet And Map Rows

Water the bed again so the profile is evenly damp, not soupy. Stretch a string to mark rows or use your hand as a quick spacing guide. Keep tall crops on the north side so they don’t shade shorter neighbors.

Transplants And Seeds

Set transplants at the same depth they grew in the pot. Firm gently to eliminate air gaps. For seeds, follow the packet’s depth; shallow sowing dries out fast in raised beds, so cover lightly and mist daily until you see green. Cooler-season greens and roots handle part shade; heat lovers want full sun.

Mulch Right Away

Top the surface with a 1–2 inch layer of shredded leaves, straw, or fine bark. Mulch buffers moisture and shields soil from splash, which helps reduce disease pressure noted by extension sources on no-dig systems. The linked sheet-mulching guide above covers benefits beyond weed control.

Watering Made Simple

Daily Check, Deep Soaks

Raised beds dry faster than ground-level plots. Use your finger: if the top inch is dry, it’s time to water. Aim for the soil line, not the leaves. Soaker hoses and drip lines make this easy and keep foliage drier.

Drip Basics

Lay a line 8–12 inches apart across the width of the bed. Run water until you see a uniform wetting pattern. Extension resources note that surface drip is easy to inspect and maintain, which helps keep flow even across the bed.

Materials And Safety Notes

Wood Choices

Cedar and larch last longer than pine. If you use pressure-treated boards, stick with new-generation, copper-based products rated for ground contact, and line the inside with heavy plastic stapled only on the sides to limit soil contact with the wood. UMN advises against older CCA-treated lumber and railroad ties, and suggests liners as a risk reducer.

Metal And Other Options

Galvanized metal beds are common. In neutral soils they hold up well; if your soil is acidic, consider a liner. Some prefab kits have had lead concerns, so buy from reputable sellers.

Timeline: From Lawn To Leafy Greens

You can plant right after building, or set up in fall so the cardboard fully weakens turf by spring. Penn State’s sheet-mulch overview points out that winter is a sweet spot for smothering with cardboard and mulch layers.

Stage	Target	Tips
Day 1	Site, frame, cardboard, fill	Overlap cardboard; water to settle mix
Day 2–7	Plant and mulch	Keep seed zone moist; add labels
Week 2–4	Establishment	Deep soak 1–2 times weekly, weather-dependent
Month 2+	Feeding and pruning	Side-dress with compost if growth slows
Fall	Top-up and cover	Add 1 inch compost; re-mulch for winter

Turf And Weed Pressure: Fixes That Work

Stop Grass From Creeping In

Extend the cardboard past the frame and cover the outside edge with wood chips. Keep edges mulched through the season. For rhizome-forming grasses, refresh the edge barrier mid-summer.

When Grass Pops Up Inside

Pluck early by hand while roots are shallow. If you missed a spot, slide a trowel under the crown and lift the whole clump. Don’t till the surface; that drags seeds into the top inch and triggers a flush.

Drainage Woes

If water lingers after a soak, your blend is too tight. Fork in a bag or two of coarse sand and extra compost. Keep adding organic matter each season so the structure keeps improving. UMN recommends periodic soil tests and moderate compost additions to avoid salt and phosphorus buildup.

Fast Reference: Common Problems And Fixes

Symptom	Likely Cause	Fix
Grass re-sprouts under seedlings	Cardboard gaps; thin overlap	Tuck new pieces at seams; re-mulch
Soil slumps below the rim	Initial settling after watering	Top up with mix; keep 1–2 in. below edge
Leaves spot after rain	Soil splash on foliage	Add mulch; water at the base
Poor growth mid-season	Low nutrients or dry root zone	Side-dress with compost; tweak irrigation
Standing water	Heavy soil blend	Fork in coarse sand and compost

Crop Pairings For First Beds

Easy Wins

Start with salad mixes, spinach, bush beans, basil, and compact tomatoes. These thrive in the depth ranges above and don’t crowd neighbors when spaced well.

Space-Savvy Ideas

Plant radishes between slower growers like peppers. Tuck scallions at the edges. Train cucumbers up a panel to keep vines off the walkway and boost airflow.

Care Through The Season

Feeding

If a soil test shows a need, add a balanced organic fertilizer at planting and again mid-season. Otherwise, a thin layer of compost around heavy feeders does the job.

Rotation And Cleanup

Rotate crop families bed by bed each year to reduce disease carryover. Keep a notebook with simple maps so you don’t repeat plant families in the same spot.

Why This Method Works

No digging means you disturb soil life less and keep weed seeds buried. Cardboard blocks light long enough for turf to fade while letting water and roots pass once it softens. No-dig approaches used widely by gardeners echo these benefits. The Royal Horticultural Society outlines the gains in soil health from skipping the spade.

Quick Math: How Much Mix To Buy

Formula

Volume (cubic feet) = length (ft) × width (ft) × height (ft). Divide by 27 for cubic yards. Bagged soil usually lists volume on the label; 1.5-cu-ft bags are common.

Takeaways You Can Act On Today

• Mow low, overlap cardboard past the edges, and wet it well.
• Set a square frame that’s 3–4 feet wide for easy reach.
• Fill with about half topsoil and half compost; adjust texture as needed.
• Water deeply, mulch right away, and check moisture daily for the first week.
• Keep edges mulched to block grass creep, and top up soil each season.