Groundcover & Plug Quantity Calculator
Calculate the exact number of starter plants, nursery trays, and extra buffer plants you need for lawn replacements, slopes, and flower borders. Works with 18, 32, 50, and 72-cell trays.
Landscape Area & Spacing
Nursery Trays & Whole Flat Calculator
Nurseries sell starter plugs in full trays. Enter your garden area and choose your tray size to find how many whole trays to order with a 10% buffer for healthy coverage:
Hillside Slopes & Hill Stabilization Guide
Flat overhead measurements underestimate how much ground there is on a slope. Move the slider below to see how steep hills add surface area and require extra plants:
On steep slopes, rain runoff can wash away loose soil. Space plants closer together (8 to 10 inches apart instead of 12) in a zigzag pattern, and lay down natural fiber netting to hold the soil in place until the roots take hold.
Mulch Depth & Weed Prevention Calculator
While your groundcover plants grow and spread, bare soil between plants should be protected from weeds with a 2 to 3-inch layer of shredded bark mulch. Check the cubic yards or bags you need below:
Popular Groundcover Spacing and Spread Guide
| Plant Name | Plant Spacing | How Fast It Spreads | Sunlight Needed | Can You Walk On It? | Best Tray Size |
|---|---|---|---|---|---|
| Creeping Thyme | 6–9 in (15–22 cm) | Moderate (~12" per year) | Full Sun | High (Great lawn substitute) | 50 or 72-cell |
| Pachysandra (Japanese Spurge) | 8–12 in (20–30 cm) | Fast spreading roots | Full / Partial Shade | No foot traffic | 32 or 50-cell |
| Periwinkle (Vinca) | 12–18 in (30–45 cm) | Fast trailing stems | Part Shade to Sun | Light occasional stepping | 50-cell tray |
| Mondo Grass | 6–8 in (15–20 cm) | Slow-to-moderate clumps | Dappled Shade | Moderate border walking | 18-pot or 32-cell |
| Sedum / Stonecrop | 8–12 in (20–30 cm) | Roots quickly from leaves | Full Sun / Drought Hardy | Light foot traffic | 72-cell plug |
How Plant and Tray Quantities Are Calculated
1. Zigzag Planting Math
When plants are placed in a zigzag pattern, they fill gaps much faster than a square grid. We multiply the square grid total by about 1.15 to account for the tighter diagonal spacing.
2. Rounding Up to Whole Trays
We take your total plant count, add a 10% safety cushion for plants that might get damaged, and divide by the number of plants per tray. We then round up to the nearest whole tray.
Groundcover Spacing & Nursery Plug FAQs
•How do I calculate how many groundcover plants I need for an area?
First convert your plant spacing into feet. For a square grid, divide your garden area in square feet by the area one plant takes up. For a zigzag pattern (which fills in faster with no bare lines), multiply your total by about 1.15.
•What are standard nursery tray sizes for groundcover plugs?
Nurseries sell small starter plants (called plugs) in plastic trays known as flats. Common sizes include 32-plug trays (great for deep-rooted native grasses), 50-plug trays (the standard size for most perennials and groundcovers), and 72-plug trays (small, economical plugs for large areas).
•Why should I always round up to full nursery flats?
Nurseries usually only sell whole trays, not individual plugs. Rounding up to the next full tray guarantees all your plants are the same size and gives you a 5% to 10% safety cushion in case a few plants get damaged during planting.
•How long does it take groundcover plugs to form a solid green carpet?
When planted 12 inches apart in a zigzag pattern, spreading plants like creeping thyme, periwinkle, and pachysandra usually form a full, continuous carpet by the end of their second growing season.
•How does sloped ground affect the number of plants needed?
Looking down at a flat map hides how steep a hill really is. Because the ground slopes upward, the actual surface area you have to plant is larger than a flat outline. On a 30-degree hill, the surface is about 15% larger, so you will need 15% more plants.
•Should I install landscape weed fabric under groundcover plugs?
Usually no for spreading groundcovers like creeping thyme or periwinkle that root into the soil as they creep. Weed fabric blocks their stems from rooting, keeping them thin and weak. Instead, use a 2-inch layer of shredded bark mulch to keep weeds down while the plants spread.
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