Good Plants for Ground Coverage: Cost & Spacing Guide

Selecting good plants for ground coverage requires more than just picking an attractive foliage type; it demands precise mathematical planning. The most common mistake homeowners make is buying 1-gallon potted plants for large areas, blowing their budget in the first hour, or planting plugs too far apart and waiting three years for the area to fill in. To establish a dense, weed-suppressing carpet of vegetation, you must align your plant spacing with your budget and your timeline.

This guide breaks down the exact dosage, spacing formulas, and 2026 nursery pricing for establishing ground cover, giving you the data needed to calculate your project costs down to the dollar.

The True Cost of Ground Coverage: Plugs vs. Pots vs. Seed

Before selecting your species, you must choose your planting format. The format dictates your initial material cost, labor time, and the time required for the plants to knit together into a solid mat.

For any area larger than 50 square feet, 72-cell plug trays are the undisputed champion of cost-efficiency. While 1-gallon pots offer instant gratification, covering a 200-square-foot slope with 1-gallon Sedum at 12-inch spacing (200 plants) will cost roughly $2,400. Buying those same 200 plants as plug trays (roughly 3 trays) will cost under $200. The trade-off is time: plugs take 6 to 12 months to fill in, while 1-gallon pots fill in almost immediately.

Spacing Matrix: How Many Plants Per Square Foot?

Plant spacing is measured from the center of one plant's crown to the center of the next (center-to-center or 'c-c'). Use this matrix to calculate your exact plant dosage based on your desired fill time.

Pro Tip: Always order 10% more plugs than your math dictates. This accounts for transplant shock, accidental damage during installation, and the need to replace early failures.

Top Good Plants for Ground Coverage (With Dosage & Pricing)

According to research from Penn State Extension, the most successful ground covers are those matched precisely to the site's light and moisture conditions. Here is the breakdown for three high-performing species, including their specific spacing requirements and material costs.

1. Creeping Thyme (Thymus serpyllum)

Best for: Full sun, dry soils, between stepping stones, and light foot traffic.

• Ideal Spacing: 6 to 8 inches apart.
• Growth Rate: Moderate (spreads 12-18 inches wide in year one).
• Dosage for 100 Sq Ft (at 6" spacing): 400 plugs (approx. 6 trays).
• Estimated Material Cost: $270 to $390.

Failure Mode to Avoid: Thyme is highly susceptible to crown rot if planted too deeply or in heavy, unamended clay. The crown (where stems meet roots) must sit exactly at or slightly above the soil grade. If your soil is heavy clay, amend the top 4 inches with 30% coarse horticultural sand before planting.

2. Sweet Woodruff (Galium odoratum)

Best for: Deep shade, dry to medium moisture, underplanting deciduous trees.

• Ideal Spacing: 9 to 12 inches apart.
• Growth Rate: Fast (spreads aggressively via underground rhizomes).
• Dosage for 100 Sq Ft (at 10" spacing): 144 plugs (2 trays).
• Estimated Material Cost: $90 to $130.

Failure Mode to Avoid: Because it spreads via rhizomes, Sweet Woodruff will escape into adjacent lawn areas. You must install a 6-inch deep polyethylene or metal landscape edging barrier around the perimeter of the planting bed to contain it. As noted by NC State Extension, containing rhizomatous spreaders is critical for long-term landscape maintenance.

3. Creeping Jenny (Lysimachia nummularia 'Aurea')

Best for: Spilling over retaining walls, pond edges, and moist, partially shaded areas.

• Ideal Spacing: 12 to 18 inches apart.
• Growth Rate: Very Fast (roots at the nodes wherever stems touch soil).
• Dosage for 100 Sq Ft (at 14" spacing): 75 plugs (just over 1 tray).
• Estimated Material Cost: $45 to $65.

Failure Mode to Avoid: The golden 'Aurea' variety requires some morning sun to maintain its bright yellow color. If planted in deep, full shade, it will revert to a muddy green and lose its primary ornamental value. Furthermore, avoid planting the straight green species (Lysimachia nummularia), which is classified as invasive in several mid-Atlantic and Midwestern states.

Step-by-Step Budget Calculator for a 200 Sq Ft Area

Let us apply this data to a real-world scenario. You have a 10x20 foot (200 sq. ft.) shaded slope under an oak tree and want to plant Sweet Woodruff at 10-inch spacing to achieve full coverage in one growing season.

1. Calculate Base Plant Count: At 10-inch spacing, you need roughly 1.44 plants per square foot. (200 sq ft x 1.44 = 288 plants).
2. Add 10% Buffer: 288 + 28 = 316 total plants required.
3. Determine Tray Quantity: 316 plants / 72 plugs per tray = 4.38 trays. You must purchase 5 full trays (360 plugs).
4. Calculate Plant Cost: 5 trays x $55 (average price) = $275.00.
5. Add Soil Amendment Cost: 200 sq ft requires roughly 15 cubic feet of compost for top-dressing. (15 bags at $4.00/bag) = $60.00.
6. Add Rhizome Barrier Cost: 60 linear feet of 6-inch steel edging (approx. 4 sections at $35/section) = $140.00.

Hidden Costs & Site Preparation Realities

The budget above assumes a relatively clean planting bed. If you are converting an existing lawn or weedy area into a ground cover bed, you must factor in site eradication costs. Simply tilling under existing grass will result in a nightmare of regrowth that will choke out your new plugs.

The Solarization vs. Herbicide Trade-off

If you have 6 to 8 weeks before planting, clear the area using soil solarization. Lay down 2-mil clear UV-stable plastic sheeting over the moist soil during the hottest part of the summer. This bakes the weed seeds and turfgrass roots, costing only about $40 in plastic and landscape staples. If you lack the time, a targeted application of a non-selective systemic herbicide (like glyphosate), followed by a 14-day waiting period and a shallow 2-inch cultivation, is the industry standard. Never plant ground cover plugs directly into active, living turfgrass; the competition for water will kill the plugs within three weeks.

Pre-Emergent Herbicide Timing

Once your plugs are established (usually after 8 to 10 weeks of active root growth), you must apply a pre-emergent herbicide to stop weed seeds from germinating in the gaps between your plants. Products containing pendimethalin or prodiamine are safe for most established woody and herbaceous ground covers, but applying them before the plugs have rooted in will stunt their lateral spread. Always read the specific label for your chosen plant species.