Straw vs. Hay as Mulch

Straw vs. Hay as Mulch

Question: I need to mulch my vegetable garden.  What is the difference between straw and hay? 

This is a frequently asked question, as folks tend to “intertwine” the two names loosely. They’ll say, “We’re going on a hayride,” when in fact they’ll be sitting on bales of straw, not hay, which is pricklier and more irritating.

Straw vs. Hay

Straw bales are the leftover hollow stalks of harvested grain plaints, most commonly wheat but also barley and oats. Straw is fluffier than hay, and its bales can be easily broken apart and used for many things, such as animal bedding, cover for freshly planted grass seeds or mulch for your vegetable garden.

Hay, by contrast, is made up of grasses – Timothy, orchardgrass, ryegrass, broomgrasses—and often mixed with the alfalfa legume. Think of hay as feed for any animal that grazes off a field. Hay is cut and gathered into large round or square bales while the plants are still green and moist. Thus, the bales are heavier and tighter, making hay more difficult to “fluff” and spread on the garden and more prone to mold or mildew. Yes, if the hay is free of weed seed and brambles, it could be used in your garden, but the reality is that most hayfields are full of weeds. There’s also the worry that the farmer may have used a persistent herbicide in the field, which could harm your plants.

Straw mulch with sweet corn and buckwheat covercrop. Photo: Fern Campbell

So, straw is clearly the better choice as a vegetable garden mulch. Its bales are much lighter, easier to handle and can be purchased at farmers’ co-ops and some big-box stores. It should be spread six to eight inches thick. Although weeds from straw are less of an issue, sometimes leftover wheat seeds will sprout in your garden. Just pull up the sprouts and lay them on top of the straw mulch.

Organic mulches should be applied after your crop has begun to grow and after the soil is warmed, but don’t wait too long if you want to prevent weed seeds from germinating. Weed the area well before mulching, and apply when there is reasonably good soil moisture and before the weather turns hot. Water well unless there’s a good soaking rainfall in forecast.

There are many other mulch options – both organic or inorganic. Whichever option you choose, be prepared to replenish the mulch as it breaks down and helps build healthy soil. This year, get a jump on the weeds by mulching your garden. Leave no soil surface bare. The exception is to leave a few bare spots for those ground-nesting native bees. By following these mulching principles, you’ll be amazed at how the weed problems recede and at the improved health of your plants and soil. Enjoy your harvest.

To learn more, check out the online resources listed below.


“Allowed Mulches on Organic Farms and the Future of Biodegradable Mulch” , National Organic Program, U.S. Department of Agriculture, Agricultural Marketing Service.

“Garden Mulches””, Kopsell, Dr David, former UNH Extension Vegetable Specialist, University of New Hampshire, UNH Cooperative Extension, August 2016.

“Herbicide Carryover in Hay, Manure, Compost, and Grass Clippings”, Jeanine Davis Extension Specialist, Horticultural Science, et. al, North Carolina State University, NC State ExtensionAG-727, 19 Feb 2020.

“Mulches for the Home Vegetable Garden”, Relf, Diane, Retired Extension Specialist, Environmental Horticulture, and Alan McDaniel, Extension Specialist, Horticulture, Virginia Tech, Virginia Tech, Virginia Cooperative Extension, Publication No. 426-326, 2020.

“Plant Injury From Herbicide Residue” , Derr,Jeffrey, Extension Weed Scientist, Hampton Roads Agricultural Research and Extension Center et. al., Virginia Tech, Virginia Cooperative Extension, Publication No. PPWS-77P, 2016.

“Use of Plastic Mulch and Row Covers in Vegetable Production” , Shrefler, Jim and Brandenberger, Lynn, Oklahoma State University, OSU Extension, HLA-6034, Oct 2016.