How to Grow Potatoes Under Mulch

How to Grow Potatoes Under Mulch

Introduction

Growing potatoes under mulch is an excellent way to get a productive potato harvest with less work. The mulch helps regulate soil moisture and temperature while suppressing weeds and reducing the need to hill up potatoes as they grow. With the right mulching material and proper planting techniques, you can enjoy a bountiful potato crop.

Choosing the Right Mulch

The ideal mulching material for growing potatoes is one that:

  • Keeps soil moist but allows good drainage and aeration
  • Moderates soil temperature
  • Blocks light to prevent greening of tubers
  • Is free of weed seeds and pathogens

Some top mulching options include:

Straw

  • Wheat or oat straw is one of the best mulches for potatoes.
  • The hollow stems provide good aeration.
  • It breaks down slowly over the season.
  • Ensure straw is seed-free to prevent weeds.

Leaves

  • Shredded leaves make an excellent insulator around plants.
  • They keep soil cool and retain moisture well.
  • Oak leaves last the longest without decomposing.
  • Avoid using leaves from trees with walnut wilt disease.

Pine Needles

  • Pine needles allow good water penetration.
  • They maintain an even moisture level in soil.
  • Their acidic nature benefits potatoes.
  • Rake up fallen needles or purchase bales.

Hay

  • Hay, like straw, insulates soil and resists compaction.
  • It should be seed-free to prevent weeds.
  • Grass hay breaks down more quickly than straw.
  • Avoid hay treated with herbicides or other chemicals.

Black Plastic

  • Black plastic mulch warms the soil, boosting growth.
  • It prevents weeds and retains moisture.
  • Poking holes allows you to hill potatoes without lifting plastic.
  • Remove plastic at the end of the season.

Compost

  • Finished compost adds nutrients while suppressing weeds.
  • It has good water retention properties.
  • Use a 3-4 inch layer, keeping it away from plant crowns.
  • Replenish compost as it decomposes over the season.

Living Mulches

  • Living mulches like clover enrich the soil as they grow.
  • They can outcompete weeds.
  • Mow or pull back living mulches from the base of potato plants.

When and How to Mulch Potatoes

Proper timing is important when mulching potatoes:

Plant First

Always plant potato seed pieces before applying mulch. Bury pieces 2-3 inches deep with at least 12 inches between plants.

After Sprouting

Wait until sprouts emerge from the soil before mulching. If frost threatens, temporarily cover plants with straw until mulching.

4-6 Inch Layer

Apply a 4-6 inch layer of mulch material around plants, leaving the sprouts exposed. Mound mulch around stems as plants grow taller.

No Mulch Touching Stems

Avoid letting mulch touch plant stems, as wet material can transmit blight and cause rotting. Leave a 1-2 inch gap around stems.

Replenish Mulch

Replenish mulch as needed to maintain a sufficient layer, especially after hilling potatoes or heavy rains. Supplement with new material.

Growing Potatoes Under Different Mulches

The mulching material you use will impact how you grow and hill your potatoes:

Straw

Straw is light and easy to hill. Rake up around stems or place new bales as plants grow taller. It breathes well so tubers shouldn’t get too wet.

Leaves

Leaves tend to mat down after watering or rain, so potatoes may require more hilling. Mound leaves up around plants, adding new material if needed to ensure sufficient coverage.

Hay

Hay can get heavy when wet. Use lightweight grass hay and supplement with new bales as you hill potatoes. Avoid compacting the mulch too densely.

Plastic Mulch

With plastic mulch, slice an X at planting sites and plant through holes. As plants grow, cut additional X’s and reach through to pull and hill soil over stems without lifting plastic.

Living Mulches

For living mulches, hill soil over stems without burying all the living material. Mow high or pull mulch back if it gets too dense around plants.

Benefits of Growing Potatoes Under Mulch

Utilizing mulch in potato growing provides multiple benefits:

Reduced Hilling

Mulching potatoes minimizes the need for hilling. The mulch naturally keeps tubers covered as they form on stems. Less soil work is required.

Soil Moisture Retention

The mulch acts as a blanket, retaining soil moisture to keep your crop consistently watered. Less irrigation is needed.

Cooler Soil Temperature

By insulating the ground, mulch keeps soil cooler even in hot weather. This prevents tubers from greening or sprouting early.

Weed Suppression

Thick mulch blocks light, preventing weed seeds from germinating. It reduces the need for pulling weeds around potato plants.

Improved Drainage

Certain mulches like straw allow excess moisture to drain away from tubers. This improves soil aeration and reduces rot diseases.

Organic Matter for Soil

As organic mulches like leaves and hay break down, they add valuable organic matter to the soil for free. This improves soil structure and fertility over time.

Avoiding Potential Problems

Pay attention to a few potential issues when mulching potatoes:

Wet Mulch Against Stems

Keep mulch from staying wet against stems or it may cause rot diseases. Maintain a barrier of air space around plants.

Compacted Mulch

Don’t let mulch become a dense mat. Compaction prevents air and water from penetrating to the soil.

Allelopathic Mulch

Some mulch contains natural chemicals that inhibit plants. Avoid using walnut leaves, which can stunt potatoes.

Slugs and Rodents

Thick mulch provides cover for slugs, mice, and voles. Use traps and baits if pests become a problem in the mulch.

Nutrient Tie-Up

As microbes break down high-carbon mulches like straw, they can deplete soil nitrogen. Supplement with a high-nitrogen fertilizer as needed.

Conclusion

Growing potatoes under mulch provides moisture retention, temperature moderation, weed control, and reduced hilling needs for an easy, productive crop. Choose an appropriate mulch for your climate and soil. Maintain a 4-6 inch layer, replenishing as needed while keeping mulch from contacting stems. With a properly executed mulching approach, you can enjoy healthful, bountiful potatoes.