How to Plant a Lawn on Hardpan

Hardpan commonly develops in desert regions.

Compacted soil, known as hardpan, exists 6 to 25 inches below the soil surface, creating a difficult growing environment for plants. Desert locations often have hardpan, as do properties where heavy construction equipment has been used recently. Results include shallow roots and moisture and nutrient blockage. Hardpan causes serious problems for trees or shrubs, also causing issues with lawns when surfaces where turf grass roots develop. Proper preparation prevents many problems with hardpan in a lawn.

Things You'll Need

• Soil probe
• Tiller
• Organic compost
• Aerator
• Landscape rake
• Seed spreader
• Lawn roller

Instructions

1. Check the depth of the hardpan layer using a soil probe or shovel. Push the tool down in to the soil as far as it goes and note the depth at which becomes difficult to push. Do this in multiple places throughout the yard to determine if there is hardpan all over the area or only in certain areas. Record any areas where hardpan exists in the first 6 to 8 inches of soil.

2. Till the areas with hardpan near the surface to a depth of at least 6 inches, taking care not to damage the roots of any existing trees. Use air tilling to break up hardpan in landscapes where multiple tree roots make thorough tilling difficult, suggests University of Florida Extension. This tilling method uses compressed air to break up soil, making it safe around tree roots.

3. Add organic amendments, such as manure or yard waste, to the soil to improve drainage and nutrient content. Apply 1 to 2 inches of composted matter to the soil, depending on how near the surface the hardpan exists. Although topdressing the soil with organic amendments works, it takes longer for the soil to improve. Instead, work amendments in to the soil by tilling.

4. Rake the soil with a landscape rake to even the ground. Use a rotary or drop spreader to sow the seed between May and July for warm-season grasses, waiting until mid-August to September for cool-season varieties. Sow seed in one direction across the lawn, then make a second pass going across the first rows in a perpendicular fashion. Rake the area to cover the seed, then pass over lightly with a lawn roller.

5. Mulch with straw at a rate of one bale per 1,000 square feet. This improves moisture retention, stabilizes soil temperature, and prevents soil erosion and seed displacement. Water the area immediately after mulching. Keep the soil constantly moist to a depth of 1/2 inch for two to three weeks, until seeds germinate. This requires watering several times per day, especially in hot weather when water quickly evaporates.

6. Reduce watering frequency, watering more deeply as seedlings grow. Aim for a watering schedule of 1 inch of water every week. Apply a starter fertilizer to encourage healthy growth in your new grass and mow when it reaches 1 1/2 times the recommended height for your grass species.

7. Aerate your lawn to reduce future issues with soil compaction and hardpan development. This is the best option once lawn becomes well established, according to University of Florida Extension. Perform aeration on an annual basis for best results.

Tips & Warnings

• Prevent soil compaction in the future by spreading 6 to 8 inches of mulch over planting locations before starting any type of construction work in the area.

References

• University of Arizona Cooperative Extension: Managing Caliche in the Home Yard
• University of Arizona Cooperative Extension: Conquering Home Yard Caliche
• National Gardening Association: Soil Common Sense
• Gardener's Supply Company: Building Healthy Soil
• North Carolina Cooperative Extension: Seeding a New Lawn
• University of Illinois Extension: Seeding and Sodding Lawns

Resources

• Sunset: Hardpan