Planting vegetables and herbs into the sides of straw bales and calling it a garden is one of the many trends in food gardening right now. Straw bale gardening is unlikely to save you any money and is about the same amount of work as a regular garden, but it does have a few advantages.
Advocates for straw bale gardening claim straw bales provide the perfect medium for root growth, allow gardeners to get a head start on gardening as the bales warm more quickly than soil in spring, and are easier than building raised beds or otherwise amending very poor soils.
Disadvantages to straw bale gardening are finding a reliable source of straw, preparation of bales and an increased need for watering.
To try it, locate the number of straw bales needed. Bales need about two to three weeks of preparation work before planting, so try to locate them as soon as possible. Local garden centers sometimes have straw bales for sale, or you might find them from a local farmer on online sale sites or in classified listings.
If you want to grow organically, the bales should be organic too. If organic is unimportant to you, you should still talk to the seller about what chemicals may have been used on the straw before it was harvested. Some pesticides have long-term residuals that can affect the growth of sensitive vegetable crops.
Buyer beware: Straw and hay are two different things that may be sold in the same-sized small bales. Straw is a better choice for gardening because it is coarser and tends to be less weedy than hay. It is the stem or stalk of a wheat plant left after the top of the plant is harvested for grain. Hay is a grass or other crop grown for use as feed or mulch and the whole plant, including the seed head is harvested.
Preparing bales for planting
Preparation of bales plays a key role in the success of straw bale gardening. It gives bales a chance to “cook” and decompose just enough to provide a warm, ideal environment for plant roots.
Set bales where you will be gardening in them in the yard, at the edge of the patio, or on your driveway if the neighborhood allows it. The site should have access to water and receive a minimum of six to eight hours of direct sun per day. Put bales on their sides, so cut edges of straw face up. Leave strings or wires holding the bales together intact.
Once bales are in place, soak them slowly with water. A specialty hose called a soaker hose may be helpful. Then add high nitrogen fertilizer. (Nitrogen is the first number in the three-number ratio found on all fertilizer.) Use three cups of fertilizer per bale every other day for a week (three applications total). Spread the fertilizer on the side that is facing up and soak it in with water. Water bales on nonfertilizer days too during the first week.
The second week, apply 1.5 cups of fertilizer per bale three days in a row. Water the fertilizer in each time. Keep watering every day. At the end of the second week, apply a fertilizer that contains phosphorus and potassium (the second and third numbers in the three-number fertilizer ratio, respectively). If you are using organic fertilizers, you may need to use two separate fertilizers to get both phosphorus and potassium.
After two weeks, check the temperature of the center of the bale with a soil or compost thermometer. If the temperature is above 80 degrees, wait a few more days for the bale to continue decomposing. Otherwise, start planting.
Planting and maintaining
To transplant small plants such as tomatoes, peppers, etc., use a trowel to wedge out a hollow in the bale and insert the plant like you would put it into the ground. Fill around the plant roots with high quality potting mix. Two plants per bale is the maximum to allow for adequate root space.
To plant seeds, spread potting mix in a row or in mounds over the top of the bale and plant the seeds to the depth and spacing described on the package. Water gently and add more potting mix as needed if it disappears into the bale.
After planting, water and weed the straw bale garden in a similar manner to a regular garden. Pay special attention to water needs as the bales may dry out quickly.
Trellises, cages and other supports can also be added as desired.
In the fall, compost leftover straw and plant material or mix it into garden beds to improve the soil.
For additional tips and support, check out one of the many books, videos, podcasts, and/or websites on straw bale gardening.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation. She is the host of “The Garden Show.”