Quick Answer
To build a vegetable garden soil mix for a Sharon raised bed — Sharon Heights, Lake Massapoag, Cottage Street area — combine 40% Topsoil Loam, 40% bulk Compost, 20% coconut coir or peat moss in a wheelbarrow on a tarp, mix three times, then fill the bed in 6-inch layers, watering lightly between each. For a 4x8 bed at 12 inches deep, you'll mix about 1.2 cubic yards total: 0.5 yards loam, 0.5 yards compost, 0.2 yards coir. Total time: about 2 hours. Total cost: about $120 delivered.
Why a 40/40/20 Mix Beats Pre-Mixed Soil
Sharon sits on tight, often clay-heavy soils. Pre-mixed bagged garden soil is too peat-heavy and crusts when over-watered. The 40/40/20 mix delivers four properties:
- Drainage from the loam and coir
- Moisture retention from the coir and compost
- Nutrients from the compost
- Structure that lasts through 5+ growing seasons before needing replacement
For Sharon-specific delivery scheduling, the Sharon landscape supply collection covers same-week bulk orders.
Step 1: Order Bulk Components (5 minutes online)
For a 4x8 raised bed at 12 inches deep: - 0.5 cubic yards Topsoil Loam 1/2" Screened - 0.5 cubic yards bulk Compost - 0.2 cubic yards coconut coir or peat moss (bagged is fine) - Optional 0.05 cubic yards Coarse Sand if site is clay-heavy
Browse the raised garden bed materials collection for current per-yard rates and the Cambridge raised-bed math Q&A for the volume calculations.
Step 2: Spread the Tarp (5 minutes)
Lay a 10x10 ft heavy-duty tarp adjacent to the raised bed. The tarp catches loose soil, makes mixing easier, and lets you slide unused mix back to a covered storage area.
Step 3: Combine 40/40/20 (45 minutes)
Pile the components on the tarp: - 40% loam (about 0.5 yards) - 40% compost (about 0.5 yards) - 20% coir or peat (about 0.2 yards)
Turn the pile 3 times with a garden fork. The first turn distributes coarsely. The second turn breaks up clumps. The third turn confirms uniform color and texture. Properly mixed, a closed fist of damp mix should crumble when you open your hand.
Step 4: Fill the Bed (45 minutes)
Wheelbarrow the mix into the bed in 6-inch layers. Water each layer lightly with a hose-end shower (not a stream) to settle the soil and remove air pockets. Repeat until the bed is filled to 2 inches below the rim.
The Sharon tomato cage timing from the Suffolk County hacks applies the same day — install cages and trellis at planting.
Step 5: Top Off and Settle (15 minutes)
Top the bed to 2 inches below the rim to leave room for mulch. Water deeply once with a long, gentle soak. Let the bed settle for 24 hours before planting. Top up another inch or two if the bed settles below 2 inches from the rim.
Materials Cheat Sheet (4x8 Raised Bed)
- 0.5 cubic yards Topsoil Loam 1/2" Screened: ~$40
- 0.5 cubic yards bulk Compost: ~$40
- 0.2 cubic yards coconut coir or peat moss: ~$25
- Delivery (Sharon): ~$25
- Total: ~$130 for a 4x8 bed
The Plymouth County garden mix review covers the bulk-vs-bagged comparison and confirms the cost advantage.
Why Each Component Matters
Loam (40%): Provides mineral structure, holds form when worked, drains excess water. The West Roxbury mowing schedule how-to covers parallel loam top-dress work for lawns.
Compost (40%): Delivers nutrients, organic matter, and the microbiome that drives plant uptake. The US Composting Council maintains specs and best practices for compost selection.
Coir or peat (20%): Holds water like a sponge during dry stretches, releases it slowly. Coir is the more sustainable choice (peat extraction depletes peatlands).
Optional sand (5%): For Sharon's clay-heavy sites only. Improves drainage when underlying soil drains poorly.
When to Build the Mix
The Memorial Day weekend (May 24-26 in 2025) is the deadline. May 27 is too late for first-year planting unless you accept a 7-10 day yield delay. Build the mix Friday or early Saturday, fill the bed Saturday afternoon, plant Sunday or Memorial Day Monday.
How This Compares to 2026
The 2026 season-close, May 1: Closing Out Spring Mulch Season Across Plymouth County, names vegetable gardens go in by May 15 — Sharon's local microclimate often pushes that to Memorial Day, which keeps May 27 within the realistic window.
For vegetable-soil specs and amendment guidance, the UMass Extension Vegetable Program is the regional authority.
