Straw Bale Gardening

Using straw bales as self-contained gardening beds would provide ideal growing conditions for many of your favorite crops.

straw bale garden

A larger planted straw bale garden will benefit greatly from the T-post and wire method. Not only does the wire serve as a later support for the growing plants, but the spacing of the wire lets you protect your plants with an easily movable poly cover.

Photo by Tracy Walsh

Content Tools

Unless you are a bona fide farmer or grew up on a farm you may find it a little challenging to distinguish the difference between hay and straw. An easy way for me to remember is by the color; hay is green, straw is yellow. Or imagine, if you will, the old saying, “I am going to hit the hay,” but substitute it with straw . . . ouch! Hay is soft, straw is prickly.

You are about to embark on a no-fail gardening journey—straw bale gardening. I have to admit, I did scoff at the idea when I first heard of it, but after I gave it a go, I loved it. Most importantly, it works. My bales survived a very harsh winter with lots of rain and snow and were still intact and ready to be planted this year with root crops.

First of all, you will not need to spend a small fortune on materials; in fact, with the exception of straw, you might have some of the materials already on hand. While I can’t give you all of the instructions in this article, I will share the basics with you. I was fortunate to catch up with Joel Karsten, author of Straw Bale Gardens between some of his speaking engagements, and he spilled the beans on what makes straw bale gardening work.

Fall is an excellent time to gather your bales. They are abundant at roadside stands along with the fall fare of pumpkins, mums and cornstalks. Use them in your autumn decorations if you are so inclined but don’t toss them—save them for next year’s garden. If you are really thrifty, wait till after Thanksgiving and you will find many bales discarded and free for the taking.

If you are purchasing straw, do not purchase wet straw. Purchase bales that are tightly compressed and dry. The tighter the compression of the bales, the longer they will hold up. Don’t worry about the coming winter, they will be just fine come spring when you are ready to set up your straw bale garden. Until your nitrogen source is added to the bales, the inclement weather will not harm them.

Hay vs. Straw

First of all, the reason I brought up the variation between straw and hay is that this type of gardening will not work with hay. Hay is too dense and it does not hold moisture well; it decomposes slowly allowing mold to develop. Slow decomposition equals smelly hay. Hay also contains many weed seeds and eventually will grow to look like a Chia pet.

Straw, on the other hand, works because its stems are hollow and wick up water and moisture. As the moisture spreads bacteria begins breaking the stems down from the inside out. Later in the process when we “condition” the bales, a nitrogen source will be added that feeds the bacteria within the bale creating the lovely compost that will be our only growing medium.

Setting up the Bales

You will want to place your straw bale garden in a spot that gets an adequate amount of sun (morning sun is good) for at least 2 to 5 hours. So, if your yard is shady part of the day, do not let that deter you. There are many plants that do well in partial shade such as salad greens, chard, kale, and spinach, just to name a few.

If space is an issue, you can grow a smaller straw bale garden on your deck but you will need to place your bale on a stall mat, a rubber mat with furrows which allows for easy drainage and air circulation. These mats are readily available at your local feed store. Do not use sheet plastic, poly sheeting, PVC tarps or any other impermeable layer under your bales. If moles, rodents and other such pests are a problem use hardware cloth (tight wire mesh) under the bales.

Position bales with the cut side up versus the folded straw side. The strings/twine/wire binding the bales should be on the sides of the bales. Once your bales are in their final position (and this may require a tarp and two people to drag them) it is time to add your T-posts and wires. Detailed instructions for this are found in the book Straw Bale Gardens.

The addition of the T-posts and the wires allow for better air circulation and the wires serve as a vertical support for the plants. “In addition we get really good photosynthesis and more production . . . the posts also serve to hold the straw bale greenhouse in place early in the season, which protects the plants from late spring frost,” Karsten said. (There is an entire chapter in his book devoted to the straw bale greenhouse.)

While it is not necessary to have the row cover/greenhouse it is helpful. “Poly covers work best early on,” explains Karsten. “The poly is NOT there to hold out the cold air, it actually serves to hold in the hot air that is being produced by the bacteria production inside the decomposing bales. Once the night temps are above record cold minimums of 27 to 28 degrees Fahrenheit then switch to a row cover to prevent overheating during the day. More people end up cooking their plants under the poly tent, than ever have plants freeze.”

Use mulch or landscape fabric between the bale rows to prevent weeds, especially if growing squash, pumpkins or melons. You do not want them growing directly on the ground. If not using the T-post method, then use a trellis or tomato cages for smaller fruits and vegetables. Please note that it is cheaper in the long run to use the T-posts and the wires over your bales. “If you run two posts and wires over 5 bales, you will have under $20 invested, whereas just two tomato cages, which require posts also to hold them up, will cost more for just those two plants,” Karsten said.

Conditioning the Bales

Now it is time to start conditioning your bales. This task takes patience. The entire conditioning process takes from 10 to 12 days. You can start conditioning them in mid to late April and be ready for planting in May. The biggest mistakes you can make are to skip the conditioning or skimp on the nitrogen during the conditioning phase.

“Conditioning is the process of getting your straw bales to compost internally to a stage at which they will support root growth,” Karsten explained. At the end of this process, the inside of your bales is not going to look like composted soil; it will look like someone has sprinkled pepper inside. If you put your hand down in the bales, it should feel very warm. It’s almost time to begin planting!

Getting the soaker hose in place is the next step. It will be your water source for the entire growing season. With the addition of a hose end timer placed before the soaker and set so that is comes on very early in the morning for 10 minutes daily during the hottest months, the roots within the bales get a consistent watering, the foliage stays dry thus keeping fungal disease at bay. If you do not have a soaker hose, use a water wand and water just at the roots of the plants. You really can’t overwater a straw bale garden; excess water simply runs out through the bale and onto the ground.

Planting into the Bales

Place a simple meat thermometer 6 inches into the bale; when the temperature is below 105 degrees you can begin planting. Alternately, you can use your hand to check the temperature. If it feels too hot, it probably is. If you are not using transplants but are seeding the bales you can direct-plant seeds after day 12 of the conditioning process. Try some leaf lettuce, collards, Swiss chard, spinach and kale. These can be planted and harvested multiple times.

It is imperative that you use only a sterile potting mix, layered on top of the bales 1 to 2 inches thick. Never—under any circumstances—introduce any outside soil, even from your own garden, into the bales. To do so will not only introduce weeds, but dangerous pathogens as well. When adding transplants remove the peat pots by cutting; you do not want to inhibit root growth.

An important rule to remember is to avoid overplanting—you want plenty of air circulation. Be vigilant against pests. Hand pluck insects off the leaves and remove any leaves that look suspicious for insect activity, especially check underneath leaves. Once your seedlings have developed their third leaf pair, it is safe to apply an organic fertilizer monthly. Opt for fish or kelp emulsion. Remember that you will be harvesting earlier than others, about 3 weeks from the planting date. Avoid leaving ripe vegetables on vines as they are attractive to insects, mold and bacteria.

If you are wondering what to grow in your straw bale garden, you have many choices! Heirloom tomatoes do exceptionally well in a straw bale garden; there are no disease worries because you are planting them in virgin soil. By keeping the bales free of outside soil you will keep all of your plants free of pathogens. Joel Karsten recommends these varieties of heirloom tomatoes to try: ‘Sutton’s Brandywine,’ ‘African Queen,’ ‘Old Ivory Egg,’ and ‘Aunt Gerdie’s Gold.’ “Planting in rotation, so that no surface area on the bales is left idle and thus wasted for any of the growing season will maximize the use of the bales in your garden,” Karsten advises in his book. 

If your bales have held up well and are sturdy, save them for next year; second-year bales are ideal for root crops. Grow your root crop inside and early cool-season crops on top of the bale. When the season is over, all you will need to do is cut the twine on the bale and let it fall apart to get to your harvest. Easy peasy!

What You'll Need to Get Started

  • Tightly compacted dry straw bales; five to 10 bales, depending on how big you want your garden to be.
  • Bag of Milorganite organic granular fertilizer or liquid fish emulsion. Use a fertilizer that is at least 20 percent nitrogen. Do not use a fertilizer as slow-released nitrogen. I found
    the Milorganite to be excellent and a bag goes a long way.
  • Hand trowel
  • Soaker hose (enough to cover the bales) or flat PVC “pin prick” hose turned upside down
  • Hose end timer
  • Sterile potting mix like Miracle Gro; one large bag will be enough for four bales. Do not use fresh manure. You can however use well-composted chicken manure.
  • Heavy duty landscape fabric to lay between rows; you can also use alternative items between rows such as an 8-to-10-inch layer of loose straw, newspaper, cardboard or carpet. If you like a more manicured look you can use mulch on top of the landscape fabric.
  • T-posts, 7 feet tall or taller; 2 x 4 lumber to reinforce the posts; wire to stretch between posts; and a post pounder. If not using T-posts and wire you will need individual plant supports.
  • 2-to-3-mm thick polyethylene plastic sheeting at least 5 feet wide (enough to cover the length of your bales).

What to Grow In Your Straw Bale Garden

  • Tomatoes
  • Peppers
  • Pumpkins & Melons
  • Squash
  • Swiss chard
  • Strawberries—replace annually and expect a very large crop
  • Annual flowers in the sides of bales—zinnias, sunflowers, black-eyed Susans, cosmos
  • Summer bulbs—Gladiolus, dahlias, caladiums, lilies
  • Herbs—Basil, cilantro, dill, oregano, sage, thyme
  • Root crops—beets, carrots, parsnips, potatoes, radishes, rutabaga, turnips
  • Avoid: Corn, asparagus, artichokes and rhubarb—they do not do well in a straw bale garden

Katherine Weber-Turcotte writes and gardens from the Pine Barrens of New Jersey. Her articles have appeared in Herb Quarterly magazine.