Featured Gardening

Growing Vegetables in Straw Bales

ONSIDER the humble bale of straw. Think beyond its reputation as a Halloween decoration and picture it as a productive part of your garden. The concept is simple: As the straw begins to break down, it turns into a rich, compostable planter that’s ideal for growing vegetables.

Although the practice of gardening in straw bales dates back to ancient times, I learned of it only a decade ago during a chance encounter with a local straw-bale guru, Kent Rogers. When my publisher asked me to write about straw-bale gardening, I tested the techniques in my own gardens and was quite impressed with the results.

Benefits of Bales

  • The ability to place an instant garden wherever the sun shines
  • A way to avoid poorly draining, hard-to-work or diseased soil
  • A far less laborious gardening experience, eliminating digging and weeding

Think of the straw bale as a large container with a volume of 40 gallons. Unlike a planter filled with potting soil, the bale begins life as an essentially sterile medium. By season’s end, it is transformed into a partially composted mass of organic matter that’s teeming with life. After the crops are harvested, the material makes a perfect top-dressing to garden beds or a valuable addition to the compost pile.

Where to Start

My advice to beginners: Start small. That way you can see if the technique works well for you. My first year involved a dozen bales, planted with tomatoes, peppers, eggplants, summer squash and cucumbers. In the second year, I expanded to 40 bales, adding lettuce and other greens, leeks, garlic, carrots, beets, radishes and herbs.

You can find bales at garden centers. Wheat-straw bales are ideal, though other types such as alfalfa and buckwheat, are reasonable substitutes. Avoid hay bales, which are often quite a bit cheaper. They often include dried grasses with lots of seeds. In addition, they break down too quickly and become weedy. Pine straw does not work well either. It isn’t absorbent and it composts too slowly.

Where to Put the Bales

Vegetable crops need at least eight hours of sun a day. More is better. Make sure you have easy access to water, too. I use bales in my garden and on my concrete driveway. A wet straw bale gets quite heavy, so consider that if you are a rooftop gardener. Wooden decks can be damaged by the constant wetness.

What to Grow

You can grow crops from seed or plant seedlings — just as you would in a raised bed or in the ground. For seedlings, consider tomatoes, eggplants, peppers and spring greens. If you’re planting from seed, start with beans, cucumbers and squash. Carrots, beets, sweet potatoes and potatoes can be grown well but are a bit trickier.

How to Prepare the Bales

Before you can plant in the bales, they need some special preparation, so buy the bales at least two weeks before you want to plant. Place the bales where you want to grow; once they are prepared, they will be too heavy to move.

Nitrogen Sources:

Conventional lawn fertilizer (29-0-4 NPK). Make sure it doesn’t include pre-emergent weed-killer. Use 1/2 cup per bale, per application

Blood meal. Use 3 cups per bale, per application.

The First Week

  • Water the bale thoroughly, until water runs out the bottom of the bale. Sprinkle the surface with a nitrogen source (see box), applying at the recommended rate.
  • Every other day, add more of the nitrogen source; water thoroughly. Do it a total of three times during the first week.
  • On the days you don’t apply nitrogen, just water the bales thoroughly.

The Second Week

  • For the next three days, apply the nitrogen source daily at half the original rate. Follow up with thorough watering.
  • After three days of adding nitrogen, water daily.
  • At the end of the week, sprinkle each bale with 2 cups of balanced fertilizer, such as organic 5-5-5. Water thoroughly.

Why so much nitrogen? It jump-starts the composting process and creates an ideal environment for plant roots. Over the course of the two weeks, the bales heat up considerably and can reach temperatures of 125 degrees F or more.

After the two weeks of treatment, the bales are ready for planting. The internal temperature should be about 75 to 80 degrees F, which you can verify with a compost thermometer. Probe from side of the bale, about halfway down. Low-tech option: Use your finger. The interior should feel warm, but not hot. If the bale still feels too hot, wait another couple days and check again.

How to Plant

To plant seedlings — tomato, pepper, eggplant and greens — make a gap or divot in the top of the bale and set the roots in place. Fill in around the roots with a good-quality, peat-based potting soil, ensuring that the seedlings are well-seated and level with the surface of the bale. Water gently and, if needed, add more soil to fill gaps and stabilize the seedling.

Care and Troubleshooting

Bales can dry out quickly because they are above ground and permeable. Be sure to water regularly. Drip irrigation or a soaker hose, draped across the top, work well.

Similarly, regular feeding is important, because frequent watering will lead to nutrient loss more quickly. Feed your crops once a week with a balanced, water-soluble plant food.

Because the bales are elevated, it helps deter certain critters, such as rabbits. I’ve found slugs to be a bit of a bother to bush beans. A sprinkling of diatomaceous earthhelps with this issue.

By the end of the season, the bales will break down, the extent depends on the crops grown in them and the weather. Some hold up well enough to plant garlic in the fall. Others collapse into a rich mound of compost, perfect for adding to containers, amending garden beds or tossing in the compost pile.

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