East Austin · Garden Maintenance · gardening · Maintenance · mulch

Straw Mulch

The death star has arrived! We’ve already had a few hot days this year but from this point on we can count on the heat being persistent and at times overwhelming. Gardeners hoping to beat the heat might consider using straw or hay mulch to protect their plants and our water budget. Last year Jackie pioneered the use of hay at our garden and the results spoke for themselves. Even with a series of +100 degree days she didn’t need to water her plants all summer long.

Straw and/or hay mulch protects the soil by preventing

  • soil erosion
  • weeds
  • drought stress
  • heat stress
  • water waste

Straw mulch prevents evaporation which helps to keep the soil evenly moist. This is particularly important for tomatoes, peppers and other plants prone to physiological stress or what I like to call “the vapours.” When the moisture content fluctuates from mud to dust and back again these plants can really suffer. Dousing their roots with cold water when the air temperature is hot adds to the problem. One symptom to look for is leaf cupping or leaf roll. In serious cases fruits can develop blossom end rot. A thick layer of straw put on the soil’s surface can protect the delicates from swooning due to moisture and heat extremes.

Straw and/or hay adds

  • organic material to feed soil organisms
  • habitat for beneficial insects

A healthy soil environment reduces the need for fertilizer and can even control pest populations.


  • be too tidy. Ruth Stout’s method was to toss straw into the air to achieve a more random distribution
  • be too cheap. Aim for a minimum depth of 3 inches.
  • buy from a source that cannot guarantee the material is herbicide free. Before bundling, most conventional growers kill these crops with persistent herbicides that will damage our broad leaf vegetable plants and can contaminate soil for years.

More fine print

Straw is usually seedless. Fresh hay may contain weed seeds. Usually this is not a problem. Turn anything that sprouts back into the soil for a nitrogen boost or pull the sprouts out while they are small. The time saved in not watering allows more time for this kind of plant care.

Mulch left to touch plant stalks may cause rot. Pull the mulch back from the plant’s stem to the drip line.

When the straw first starts to rot it may suck some nitrogen from the soil. This problem is temporary. Add a nitrogen boost when you lay the straw down or at season’s end if this is a worry. Otherwise, trust in the soil organisms to circulate nutrients.

Do you have a favourite mulch? Let us know in the comments.