Every year I do at least one significant experiment in the garden, this year I was excited to try out straw bale gardening. I had been hearing positive reviews about it for a couple years and it seemed like a good fit for a few key reasons:
1) It’s a cheap way to increase growing space.
2) It’s a fast way to increase growing space (we didn't get back from our worldschooling adventures until May so I didn't have any time to spare, I had to rush like mad to get the warm season garden going in time).
3) It enables me to grow in a spot that has really poor soil but great sun exposure.
4) It’s noncommittal. We haven’t fully figured out what we are doing with some parts of our garden yet and so I'm not ready to commit to making nice, gopher-proof, raised beds. The bales are a good temporary solution.
5) The bales will make for great compost next year.
How it works:
Before planting, the bales--which are basically blocks of carbon-- need to go through a two to three week conditioning process. Essentially this process is adding nitrogen to the carbon so that bacterial decomposition can take place. As it decomposes the straw will turn into compost and supply enough nutrients for your plants. The conditioning process is pretty simple but you do need to follow the schedule precisely for two weeks. You can read specific instructions here.
During those two weeks you will alternate between watering and feeding the bales a high nitrogen organic fertilizer (if you're not grossed out you can save some serious $$ by using human urine). You'll know you're on the right track when your bales start cookin! By the third day our bales had gone from 70F to 110F. A word to the wise though, don't plan a garden party during this time, the smell is similar to a wet dog who has just rolled around in the compost heap.
Once the bale cools it's time to plant!
They say you can plant almost anything in straw bales, though tall crops are a little tricky and need additional support. We planted a wide variety of crops to see what thrived in the bales including: peppers, melons, cucumbers, winter squash, summer squash, flowers, collards, beets, basil, onions, sweet potatoes, cannabis, bush beans, turmeric, tomatoes, and cabbage. The winter squash were the most successful, most other crops were less successful, especially compared to the soil grown crops. That leads me to some of the downsides of growing in bales...
The Cons:
* The #1 con is that it's been hit or miss in terms of plant health. In general, the plants don't seem as healthy as my soil-grown crops, I see that in a couple ways. First, the leaves are smaller than usual on all the crops. This is true of most organic straw bale gardens I've seen around town and on Instagram too, the leaves just aren't as big and lush as they typically are. The pioneer of strawbale gardening, Joel Karsten, has gorgeous crops, but I'm not sure if he grows organically and he's been doing it for decades now so he's got everything dialed in. I believe it is possible to grow soil-sized plants but that it would take me awhile to get there. Secondly, growth seems much slower for every crop. Lastly, transplant shock seemed to last forevvvvvver; it took much longer for the crops transplanted in the bales to start growing compared to the ones I planted in the soil at the same time. Less health and vigorous growth translates to less food for us.
* The conditioning process is fairly labor intensive and precise.
* Figuring out the watering was challenging throughout the season. It takes a ton of water to get the bales saturated in the beginning. If you plan ahead and got the bales in the fall so they got soaked by winter rains, that wouldn't be a problem (though you'd have bales already degrading, so they wouldn't last as long... that's a tough trade). We got new bales and used the most water we ever have on this property during the month we set them up. We have water restrictions here so that ended up being costly to us. Additionally, because it's a temporary set up for us (one of the Pro's!) I didn't want to set up irrigation, so all the watering was done by hand. We have learned over and over again that any hand watering is a pain in the ass and much less reliable. I don't care who you are, hand watering is inconsistent. You would definitely want to set up a soaker hose system if you were planning on growing in bales every year. Once the bales are saturated they only need a little bit of water, but they need it everyday because the top dries out so quickly. It's very easy to over water and wash out all the expensive fertilizer you added.
* You have to keep feeding the bales, so we spent a lot of money on fertilizer. I've never bought so much fertilizer in my life. This is not the type of gardening I like, it's the opposite of closed loop. I don't think a top dressing of my usual compost would fill the nutritional need, but maybe? I bet if I had my vermiculture compost going and fed the bales with a worm tea brew every week that would work, but I didn't have worms this summer so I've been relying on store bought organic fertilizer. In general, I feel like I need to be much more hyper vigilant about nutrient needs in the bales vs. soil.
* There's a couple of claims about straw bale gardening out there that ended up being false for us. One is that there aren't any weeds to deal with. Well, bind weed seems to love the bales and has no problem shooting up through them (even when the bales are on cardboard). Another claim is that straw bale gardening is less labor intensive. This may be true for some people but with hand watering, fertilizing, weeding, trying to stabilize the bales, and running to the nursery for more fertilizer, it hasn't been true for us. Lastly, it is marketed as an "accessible" way of gardening. As someone who worked as a garden coordinator at a center for people with developmental disabilities, this claim really gets my goat. Bales are knee high at the start and get lower as they decompose; you still have to bend over quite a bit. If you are in a wheelchair, there's nowhere to put your legs. I don't consider this accessible. Lastly, people claim it's cheaper than raised beds, but that deserves it's own bullet point...
* With the cost of fertilizer, water, and bales and with the fact that they only last a season or two and then you have to buy new ones, I don't think this can be considered low-cost. The cheapest bales we can find here in urban Santa Cruz, California are about $9 each, I've tried many times to find older discounted ones but have never been able to. If you don't have a truck or van you'll pay a delivery charge too. Over the long-run this is definitely more expensive than building a raised bed and filling it with good, organic, bulk soil that can be continually renewed with free homemade compost.
* It's hard to find organic straw.
The Pro's:
* You can grow anywhere, including on cement
* It's fast to set up...kinda. We definitely couldn't have made gopher proof raised beds in the amount of time we had this spring, but we are very slow at construction projects. For a person that can whip together raised beds quickly, especially if they don't need to be gopher proof, it would be faster to do the raised beds since the bales take 2 weeks to condition.
* If you time it right, the bales can warm up sooner than soil in the spring, allowing you to get an early start on the growing season. Theoretically. With the prolonged transplant shock we experienced I'm not so sure it actually gives you much of a head start.
* You can get some pretty gorgeous compost material out of it.
* It's easier to harvest sweet potatoes, potatoes, and root crops. (Though the bale will be done after that, no second crop.)
* It's an interesting science experiment and definitely has a place in school gardens and demonstration gardens.
Conclusions...
I am glad we tried this experiment out. However, of the 29 bales we planted I'd say only eight of those performed to the level I'd expect if the plants were in soil. That's not very good. There's a couple of *almost* successful bales-- like the bush beans which have produced a fair amount of beans but the plant itself is half the size of the plants that I transplanted into the soil at the same time; or the melons that have produced more fruit than usual but they are all tiny, the size of softballs. Eight out of twenty-nine though, those aren't good numbers.
Here's a general breakdown of how each crop did...
Crops that were happy and comparable to soil grown crops: winter squash (6 types), arugula, and Lebanese White Bush Marrow (a summer squash that thrives in even the worst conditions).
Mixed bag, in some ways good, but in other ways decidedly worse than the same crop grown in soil: peppers, sweet potatoes, cabbage, cucumber, tomato, basil, tromboncino squash, cannabis, bush beans, melons, beets, turmeric.
Crops that did poorly: golden zucchini (the worst performing zucchini I have ever grown), peppers, onions, collards, melons, snapdragons and petunias.
I would definitely consider growing winter squash in bales again, especially in this one tricky spot I have, but otherwise I'll probably stick to keyhole beds and traditional raised beds with soil. Have you had a different experience? Or have tips or tricks? Tell me about them!
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