I live in West Texas and I've been at my current place for 3 years. The first year I tried a standard garden but didn't get out of it what I had put into it because the ground is quite hard, which makes it hard for me to till and the plants to set roots. That winter, my wife found a book on straw bale gardening and we tried that for the second year. Even 'tho we started in late April, several weeks after we should have, we had cherry and grape tomatoes until the first freeze in November.
The picture above is the garden for 2016. 8 bales of wheat straw. We plant 2 started plants per bale so we have 16 growing positions, unless we want to plant some seeds. Currently the thought is 6 tomato plants, a couple bell pepper plants, a couple zucchini, a couple cucumber, and a couple watermelon. One bale will be used for seeded plants, probably a leafy lettuce that worked out well last year. The poppies are from a wildflower mix my wife spread a couple years ago. I left them there because they won't take away from the plants in the bales and also they keep the pollinating insects around.
You want wheat straw bales. Not hay of any kind. In case you weren't aware of the difference, hay is any grassy plant who's sole reason for being grown as a crop is to make hay. Straw is the leftover stalks of a seed bearing crop, in this case wheat. The combine threshers they use these days are very efficient, taking all of the wheat grains and leaving the straw behind. This is important because you want a few volunteer plants as possible. Since you are making the bales able to support plant life, any seeds in them will sprout.
Step 1: Conditioning the Bales
The first step is the same as any garden, plan it out. What do you want to plant? Does it need full sun or partial sun? How much space do you need to leave in between the plants? Arrange the bales according to the plan, with the bales sitting up on their long narrow end. The cut ends of the straw stick out the sides and those straw straws will get the water all the way into the bale.
The second step is unique to straw bale gardening. You have to condition the bales, get them ready to support plant life. It's very easy. Go pick yourself up some fertilizer that is high in nitrogen. Fertilizer has it's own nutritional information label, it's a series of 3 numbers separated by a dash. I found some lawn fertilizer that was 30-0-0 for this year. Last year I used 15-15-15. Spread about 1/2 cup per bale and water it in. Use enough water that it's coming out the bottom of the bale. The second day, just water the bales, same amount of water as the 1st day.. Third day, water and fertilizer. Fourth day, just water. Water every day and fertilize every other day. In 2 weeks it should be ready to go. Take your garden trowel and stab it in, cutting out a square the size of the trowel. When you pull that square out, the inside of the bale should be much darker, warm, and maybe a little sweet smelling. That is the straw decomposing. Adding the water and the fertilizer makes that happen quickly.
Added some pictures showing the fertilizing of the bales. The shaker holds about 4 cups which works out well with our 8 bales @ 1/2 cup per bale. Just shake it on evenly as seen in the second and third pick. Then water it in. I just water until the white nitrogen granules have melted into the bales.
Step 2: Planting Starter Plants
Now for the fun part, the planting. You'll still need some garden or potting soil. I had a full bag and a partial bag from last year. Set our your plants to see where you want them. Where you see two plants together, one is a squash or melon and the other is a marigold. Last year squash bugs killed off my melons and squash so I'm seeing if the marigolds will keep the squash bugs away. I read about it on the Internet, so it must be true.
Cut in a hole so the plant in the pot just sits in it.
If your plant came in a decomposable pot, remove the plant and set it aside for a moment, then tear up the pot and put the pieces in the bottom of the hole. Toss in a handful or so of your soil, enough to cover the bottom of the hole.
If your pots are plastic now you remove the plant from the pot and place it into the prepared hole. Spread a handful of potting soil around the plant, just like you were planting in a traditional garden. Don't forget to break up the root ball a bit to promote growth.
Water the garden as appropriate for your area. Last year I watered for a couple minutes every hour. It gets hot around here and the humidity is often low.
Updated on April 24th, 2016
Step 3: Planting Seeds
Planting seeds is bit more traditional. Start by spreading a half inch thick layer of potting soil over the bale covering the area you wish to use side to side. Lay down your seeds, I used seed tape which makes this very easy, and then cover the seeds with soil as per the seed packet directions. It was a little windy, so I wetted the seed tape to help it stay in place.
Now, water the garden as appropriate for your area. Last year I watered for a couple minutes every other hour. It gets hot around here and the humidity is often low. The straw will drain that water quickly from the outside surfaces of the bales, but it will also keep water inside which will attract the roots of your plants.
Step added April 24th, 2016.
Step 4: Midsummer Update
So here is the overgrown garden and a couple cups of yellow cherry tomatoes. I harvested that amount twice a week by that point and it kept up until the frost came in early November. There were still blossoms and green tomatoes on the vines so they would have kept producing for quite a while.
Before that 'tho, there was a bountiful harvest in late May. Way more tomatoes than we could eat and I ended up taking a 5 quart container, packed full, to family . There are also squash, bell peppers, and watermelon in the front row. The root vegetables were in the middle row and being overtaken by the tomatoes. That fence in the background is 6 feet tall. All the tomato plants would have been that tall or taller, but the tomato cages collapsed. This year, I'm putting in a 3 wire fence in front to get the plants to grow up and make harvest easier. And not as many tomato plants.
Despite my valiant efforts, the squash and watermelon plants got eaten by squash bugs. This year, the squash and watermelon plants are getting separated and marigolds will be planted around them to try and keep those bugs away.
Step 5: Final Harvest
Here is the final harvest. The yellow cherry tomatoes had slowed but the red grape tomatoes were still going strong. The peppers were picked to finish ripening inside, away from the coming frost. It was about August that I recalled making a harvest bucket out of an empty gallon milk jug. Just cut around the lid and remove the half opposite the handle.
But the real final harvest is yet to come. Your bales will have collapsed onto themselves by this time. They will decompose further over the winter and in the spring, you'll have a garden of topsoil. And probably a few volunteer plants.
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