How do you prepare soil for leeks?
Written by
Olivia Mitchell
Reviewed by
Prof. Martin Thorne, Ph.D.Leeks do require a quality product to grow in, and their shallow roots do like loose, rich soil, so you will want to carefully prepare the soil before planting. First, check the drainage. Dig a hole about 12 inches deep and fill it with water. If it does not drain at least 2 inches per hour, you might amend it with grit. Leeks do not like wet feet.
Soil Testing
- Use pH meter to target 6.0-7.0 range
- Add lime if below 6.0 (1 cup per 10 sq ft)
- Mix sulfur if above 7.0 (½ cup per 10 sq ft)
Amending Soil
- Clay soils: 3" compost + 2" coarse sand
- Sandy soils: 4" compost + 1" peat moss
- Loam soils: 2" aged manure (6 months old)
Avoiding Pitfalls
- Never use fresh manure, causes forked roots
- Skip wood ash (raises pH too quickly)
- Remove rocks larger than 1" (2.5 cm)
Compost tea provides an energy jolt to the biology of the soil. I brew 5 gallons of compost tea every week during preparation. I use 1 cup of worm castings, and add ¼ cup of molasses, then aerate for 24 hours. I apply the compost tea as a drench to my beds, 3 days before planting my seedlings. This dramatically increases the microbial activity in the soil, which gives my seedlings a head start against diseases.
Trench planting? Dig 8-inch (20 cm) trenches and line with 1 inch (2.5 cm) perlite for drainage. Once you have made the trenches and lined them with perlite, simply backfill with compost-enriched soil. This trick avoids stem rot in rainy areas. My leeks in the Pacific Northwest survived record rains with this method.
Avoid using synthetic fertilizers at the time of planting. Instead, apply 1 cup of bone meal and ½ cup of kelp meal in each 10-foot row. These products are slow-release nutrients that provide nutrients to leeks over 8 weeks without any salt buildup. Top-dress with some compost when the leeks reach the thickness of a pencil stem.
Read the full article: How to Grow Leeks: Beginner's Guide to Sweet Harvests
