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Great Gardening by Sally Cunningham: Straw bale gardening

Last week a friend sent me a New York Times article from March about straw bale gardening, reminding me that everything old is new again – and that gardening is a hot topic even in the middle of New York City.

Planting into straw is an ingenious gardening technique, with many variations, that well suits gardeners with limited space, no soil, poor soil or a need for easy-on-the-back raised beds. The idea is surely new for a generation of relatively young gardeners who missed the 1970s organic gardening surge, although it’s built on a well-honed premise. And if you feel you’re starting late this season, and didn’t prepare your garden soil, you can have a nearly instant garden this way – even on the driveway or patio.

The concept is simple: Plants can grow in any organic matter that is partially decomposed, and straw decomposes quickly, creating a form of compost. Just acquire some bales of hay, take a couple of simple steps to prepare them, and plant directly into the bale. It’s a raised-bed garden with a twist, just fresh enough that Cool Springs Press recently published “Straw Bale Gardens” by straw bale guru Joel Karsten (

Prepare the bale bed

First, find some bales of straw. A couple of phone calls informed me of straw available at farm supply stores in the area, around $7 per bale. Experienced growers sometimes use hay bales. Hay is nutrient rich but contains many more weed seeds than straw, so your mini-garden could resemble a mini-field instead of a salad plot. Stick with straw.

Choose a sunny location, unless you’re growing only shade-loving plants. Place the bales cut end up, which is much easier for planting into than the other direction. Now soak the straw for about a week. Poke your hand inside a few times, to feel how hot it can get; you’ll understand why you couldn’t have planted into a fresh bale immediately. This heat buildup is the same thing that happens when you build and then moisten a compost pile. It’s also the cause of many a barn or silo fire that happens when wet hay is baled and stored prematurely. Decomposition gets hot. Let your bale cook a week or two before it’s a garden bed.

Fertilizers, natural or synthetic, speed up the decomposition process and add nutrients to your straw bale garden. You have choices. If you aren’t committed to organic gardening, you could sprinkle a couple of pounds of any balanced synthetic fertilizer (either 5-10-10 or 10-10-10 fertilizer) per bale, and water it in for 10 days or so, until the heat simmers down. (After a week, if the bale still feels warm inside, it’s ready; some heat encourages root growth.)

If you’re in my organic gardening camp, you can achieve the same goal by sprinkling any organic fertilizers onto the bale and watering: an inch or two of any manure or a thin sprinkling of blood meal, bone meal, cottonseed meal, fish emulsion, or another organic fertilizer. The amount of organic fertilizer to use is not critical, since it breaks down slowly and doesn’t burn plants. You can even use fresh manure because it won’t be touching the plant roots.

Plant and tend

After the heat-up and cool-down, planting is easy. Separate the flakes of straw and plant into them. I suggest using a scoop of potting mix or finished compost around the young plant’s root ball to give the roots a start. Some advocates tell you to layer a few inches of topsoil on top of the bale. It all works.

The bale garden is the right setting for intensive and companion planting combinations. Include some flowers and herbs; try vertical arrangements using wire cylinders or chicken wire fencing, solidly staked, for beans to climb. One bale could hold two staked or caged tomato plants surrounded by salad greens and herbs. Try borage, nasturtiums and other pollinator-friendly and edible flowers.

Water any time the bale feels dry, more often than for a garden in the ground. Once a week add fertilizers, following product instructions. Organic choices include fish emulsion, compost or manure tea, Doctor Earth or other commercial products. Pick out slugs and weed as needed.

After this season

But what about next year when you have a pile of half-rotted straw on your driveway? You might get a second season from a bale if you prop or tie it up. If it’s already on top of soil, this is the perfect way to create a new raised bed. Just leave it in place and plant directly into it next season – or have a fall crop this year.

You could also enclose the straw bales in hardwood boards or rocks at the start of the project, or you could build the enclosure around the decomposing bed at the end of the first season. Many types of prefab raised beds can also be purchased, including a kit from a local inventor who has styled attractive sculpted metal corners so that all you need to add are the boards. If you surround straw or hay bales with wood, consider lining the sides of the bed with heavy builders’ plastic to slow the inevitable rotting.

I began with a suggestion that this idea is a fresh take on old techniques – no dissing Joel Karsten’s terrific idea, book and successful online education. In many cultures, similar methods build on the idea of composting in place with direct planting into the layered bed. For decades, Rodale books and magazines have taught ways to improve soil by building a new compost pile in a new part of the garden year after year, and planting into it. In “Great Garden Companions,” I showed the German “huegel” (hill) method along with raised bed techniques, and Pat Lanza’s now famously coined “Lasagna Gardening” rests on the same principles in a catchy presentation.

Horse people think of straw as bedding. Organic gardeners typically use it as a great mulch and soil builder. Now straw is becoming the best new addition to your gardening bag of tricks. Try it.

Sally Cunningham is a garden writer, lecturer and consultant.