Straw Bale Garden vs Traditional In-ground Garden – A Critical Comparison

Straw bale gardening seems to be an “in-thing” to try and I have written about it in Pros and Cons of Straw Bale Gardening. I see people on line praising the technique, but I also see a lot of people reporting failure. What is rare is any side-by-side comparison of straw bale gardening to traditional in-ground gardening. Even proponents of straw bale gardening don’t provide evidence for their claims by making a comparison.

I wanted to see for myself how well it worked, so this year I decided to do a comparison between my traditional vegetable garden and straw bale gardening. Here is what I found.

Straw Bale vs Traditional Gardening – Experimental Setup

I set up two straw bales and planted the same things, at the same time, in each one, as well as directly in soil in my normal zone 5 garden.

After conditioning, the Control Bale was treated just like my soil garden. It was fertilized and watered whenever I did the same to my soil garden. I wanted to treat this bale as closely as possible to my normal garden practices to do a proper comparison of the two techniques.

The Test Bale was also conditioned but after that it was treated according to the suggestions made by happy straw bale gardeners it was watered whenever it started to dry out (which was daily on hot days) and it was fertilized every week.

Both straw bales were conditioned as described in my previous post. All three gardens are within a few feet of each other so they all get the same amount of light and air temperature.

The Straw Bale Conditioning Stage

Traditional Garden

I raked last years straw mulch off in early April to allow the soil to warm up. That’s it. Nothing else was done.

Straw Bales

Conditioning started April 5, which is about 2 weeks before I normally plant cool weather crops. Early April this year was unusually warm with daytime temperatures in the low teens (centigrade).

Conditioning ended April 14. April 13 to April 17 was very cold with daytime highs of 3-5 C (37-42 F).

I followed the advice to water daily, but this did not seem to make much sense to me. Once the bales were wet, they never dried out and probably only needed to be watered every 3 days. All this extra water probably washed a lot of the fertilizer right out the bottom of the bales.

There was no visible decomposition during conditioning and the bales never got warm to the touch, even in the center of the bales. I suspect that conditioning has to wait until warm weather, but this is never mentioned in the procedures for this technique.

By June 28, the straw was turning darker, showing some signs of decomposition. Conditioning took about 10 weeks, not the 2 weeks claimed by many.

Planting Cool Weather Crops

Sugar Snap peas were planted in the ground early April but none were planted in the straw bales because they were still being conditioned. This is a major drawback for straw bales. The peas in soil were an inch tall by the time the bales were conditioned and ready for planting.

The first planting in straw took place on April 22. An inch or two of soil was placed on top of both straw bales. Both bales and my normal ground were planted with a row each of carrots, beets and lettuce. A few radish seeds were also added to the beet row.

Germination of Early Planting

The first half of May turned out to be quite cold and by May 9 we had nights of -4 C (25 F).

Lettuce was poking out of the ground by May 1 and by May 7 beets and radish were also showing in the ground.

Nothing germinated in either straw bale.

I suspect that the straw bales were colder than the ground which slows down germination. The other problem is that watering the bales washed the soil down the sides of the bale and into the bail. A week after sowing, I could see radish seeds siting on the straw which would make it hard for them to get their initial root into the bale without drying out.

Soil on the straw bales also dried out much quicker than the ground. Everything was watered daily, either from the tap or by rain, but it might not have been enough water for the bales. The soil on the bales dried out very quickly and much faster than the ground.

Carrots, beets and lettuce were harvested normally from the ground but these crops were a complete fail on the straw bales.

Late Planting of Peas in Straw Bales

I had germinated some sugar snap peas in pots for another experiment and these were about an inch tall, so I decided to plant one in each location on May 8. The peas were in 1/2 gal pots which were easy to plant in the ground.

Planting in the bales was more difficult. Since the straw still had not decomposed, it was hard to dig out enough straw for all the soil in the pot. So I removed half the soil from the seedlings and planted them in the straw.

The pea plant in the control bale started to grow a bit, and then died. I think its root system never get established.

The test bale did much better. Growth was as good as in the ground, and the first flowers showed at the same time as the plant in the ground. Unfortunately, chipmunks cut off the stem a few days before harvest time, so the peas never fully developed. However, I am sure the production would have matched that of the same pea plant in the ground.

For comparison, the early planted peas that were planted in the ground were 5 feet tall by harvest time. At the same time, this late planting was only 2 feet tall in both soil and in the bale,  and were not ready for harvest. The early planted peas also produced more pods. Early planting of peas in cold climates is very important.

Growing Beans in Straw Bales

Blue Lake pole bean seed was planted early June in both bales (2 seeds per bale) and in the ground. Only one of the seeds sprouted in the test bale, while both sprouted in the control bale. The ones in the ground showed normal green coloration. The one in the test bale was a bit darker, due to the higher fertilizer rate. The ones in the control bale were very light green, almost yellow, probably due to a nitrogen deficiency.

June 30:

Ground – the beans were already climbing and were 2-3 feet tall.

Control bale – no sign of climbing and plants were only 6 inches tall.

Test bale – same as the control bale

July 13:

Ground – beans were 4-8 feet tall.

Control bale – plants are 2 feet tall and leaves are still fairly yellow.

Test bale – plant is 8″ tall, still not showing signs of climbing, but it is darker green.

August 1:

Ground – harvested first beans and there are lots of small beans and flowers.

Control bale – flower buds showing but none open yet. They are at least 10 days behind beans growing in the ground with first flowers finally opening August 9.

Test bale – same as control bale.

Bean seed did grow in the straw bales, probably because the seed is larger and the straw was starting to decompose by the time they were planted. Growth was slower in both bales and harvesting started about 10 days after the peas in the ground. In a short season like you have in zone 5 – a 10 day delay is significant.

Growing Tomatoes in Straw Bales

Late May and early June were colder than normal, so tomato planting did not take place until mid June. The cultivar Early Girl was planted in the ground, and one plant was added to each straw bale. The straw was starting to show some decay, but not very much. The plants for the straw bale were planted in a hole about 4″ deep, along with soil from the pot. The ones put in the ground were planted with about a foot of stem covered in a shallow trench, as is my normal custom.

This deep planting is expected to provide larger plants with larger root systems but it is not a suitable method for planting in straw bales because you can’t dig a deep enough hole.

June 30:

Ground – plants were 18 inches tall and are starting to flower.

Control bale – plant has made limited growth of a few inches. It was showing flowers but the leaves were yellow-green.

Test bale – plant was growing well, had flowers and dark green leaves. These leaves were even darker than the plants in the ground.

July 13:

Ground – none of the tomatoes showed blossom end rot (BER) and I rarely see this in my garden.

Control bale – tomatoes are a bit smaller than in the other two locations and they show no sign of BER.

Test bale – the largest tomatoes are showing BER and were removed. BER is due to a lack of calcium in the fruit which is usually caused by watering issues.

Note: The BER was only a problem on the first few tomatoes of the season and only in the test bale. Later fruit was BER free in all three situations.

Aug 5:

Ground – harvested the first ripe tomato.

Both bales – plants are growing well, producing a good quantity of tomatoes, but none are ripe yet. Plants seem to be about a week behind the ones in the ground.

Because tomatoes are planted later in the season there is enough time in spring to condition the bales before planting. Growth in the bales was surprisingly good, although not better than growing in the ground and the harvest started later.

Straw Bale Gardening vs Traditional Gardening

A big issue with straw bale gardening is the extra effort needed to make this method work. You have to get the bales and then go through the conditioning process before you can plant. It is clear from the above, that the conditioning process does not work in a cold climate for early crops. It might be possible to condition the bales during the previous summer so they are ready for spring planting, but that is not normally advocated. In comparison, the soil is ready to go anytime.

Straw bale gardening requires more water and fertilizer than traditional gardening. Water is becoming a scare resource in some areas, and all that excess fertilizer will end up in local rivers and lakes causing unnecessary pollution. Not to mention the extra cost.

Once my seeds have sprouted in soil, I only need to water once or twice a week if we get no rain. Why would I want to water every day?

Crops seeded in early spring, in my climate, don’t work in straw bale gardening. They might have a chance if the bales are conditioned the previous summer, and they probably work in warm climates.

Transplants which are planted later in the season, like tomatoes, do work in straw bales but even for these the total harvest period is shortened; a problem for short season climates.

What does the straw add to the process? There is some decomposition, but the amount of nutrients this would add during the growing season is minimal. The material provides a lot of air to the roots, but also requires much more watering to prevent drying out. The bale is higher, so it does mimic a raised bed. The plants are basically growing in the water surrounding the pieces of straw, very much like a hydroponic system.

Conclusions:

1. There seem to be no benefits in using straw bales over conventional growing in the ground.
2. Traditional gardening is less work, allows for an earlier start to the season and requires less fertilizer.
3. None of the crops tested performed better in straw bales.
4. You can’t treat the straw bales like you do your traditional garden. Doing so results in plants that are stunted because they don’t get enough water or fertilizer.
5. Straw bale gardening is just a complicated way to do hydroponic gardening.

Should you use straw bale gardening? I think that it has a place where there is no soil, or the soil is too contaminated for growing food. Other than that, traditional gardening is a better option.

If you use it in zone 6 or colder, you should condition it the previous summer. That means that you need space for two bale gardens – one for this year with plants, and one for next year. Seems like a waste of space to me. Colder climates that don’t have any soil may be better off going with containers.

Does straw bale gardening work? Sure it does, and I am sure that with more experience my crops would do better, but even if that happens it is still more work and wastes resources. Growing in soil is so much easier.