Pros And Cons Of Straw Bale Gardening

Straw bale gardening has a small but steady following. Historically, it has been used for a long time, but fell out of favor as more traditional gardening practices developed. In recent years it has seen increased interest but so far it is mostly a novelty form of gardening. Is this a technique we should all be using?

In this post I'll look at the claimed benefits and examine the pros and cons of the system.

What is Straw Bale Gardening?

In short, you take a bale of straw and condition it for a couple of weeks by adding fertilizer and water. Then you plant in it. It is used mostly for vegetables, but anything could be grown in it.

The straw slowly decomposes providing nutrients for the plants and an airy environment for the plant roots.

It has been discussed on social media for a number of years and I have kept an eye on many such discussions. Each one has a small number of people who use the technique and a larger number who have tried it and stopped using it because it produced poor results.

When faced with claims of poor results, experts are quick to comment about the fact that the straw bales were not conditioned correctly. Apparently, this conditioning step is a critical part of the process, and I'll have a closer look at it below.

The straw bales are only used for one season since the amount of decomposition is too high for them to be used again and diseases are more likely to be a problem the second year. Gardeners who only do straw bale gardening will then have a pile of old straw to get rid of.

Conditioning The Straw Bales

When I started the review of straw bale gardening I assumed that there was a "preferred correct" way to condition them. This is mostly because experts make such a big deal about doing it RIGHT!

Garden Myths book by Robert Pavlis

One of the early promoters of straw bale gardening is Joel Karsten. I reviewed several of his videos and blog posts containing his quotes, describing his technique and in every one, the conditioning process is a bit different. What is very odd is that the NPK formulation of the fertilizers used are not even mentioned. Instead you get some generic comment like, "add the organic fertilizer for several days".

I ended up with a dozen different "conditioning" procedures. The following procedure is based on the most common approach.

Water the straw bale
Add 1/2 cup urea and water it in until water runs out of the bottom
Day 2, water the bale
On day 3 and 5 repeat step 2
On days 4 and 6 repeat step 3
On days 7, 8 and 9 add 1/4 cup urea and water
On day 10, add 1 cup of 10-10-10 and water
Plant on day 11, provided the temperature is warm, but not hot (about body temperature)

Another way to condition straw bales, photo by Marina

The goal is to add nitrogen and water for about a week to start decomposition. Then add a more balanced fertilizer for the plants. After 10 days, this process is complete and you can plant.

Organic gardeners can use blood meal instead of urea, and compost in place of a balanced fertilizer. Some say you should not use manure, other say you can use it. Some use urine, and others use compost tea.

Soil Science for Gardeners book by Robert Pavlis

Lots of people recommend adding bonemeal on day 1. Bonemeal is mostly calcium and some phosphate. It breaks down very slowly so there seems to be little point in adding it.

Some people fertilize every day, others every second day. Some water twice a day.

As you can see there really is no right conditioning process.

Does Straw Bale Gardening Work?

It does work. We know that because some people use it and get vegetables.

But that is not really the important question. The important question is, does it offer some benefits over and above traditional gardening, such that it makes sense for gardeners to switch?

Claimed Benefits

Here are some of the claimed benefits I found.

No weeds
Inexpensive
No digging required
They generate their own warmth, extending the growing season
Straw bale gardening lets you control the nutrients
Instant, rather inexpensive raised bed
Garden without soil
Less bending
Eliminates soil borne diseases
Works were there is no soil, or soil is contaminated

Lets have a closer look at each claim, and compare straw bale gardening to traditional gardening done in soil at ground level.

Building Natural Ponds book, by Robert Pavlis

No Weeds

This depends to some extent on the source of the bale. Many do contain weeds, and reports from users make a point of complaining about the weedy environment they make.

Soil also has weeds, but mulching with straw eliminates almost all of them. Done properly, weeds are not a problem in traditional gardening.

Inexpensive

The cost of the bales depends on where you buy them. They certainly are not cheep in garden centers. I get my straw from a local farmer and they are not expensive, but I use it as a mulch and one bale covers a large area. In straw bale gardening you don't get much surface area from one bale since they are used on their side, not laying flat.

For most city slickers, straw bales are not easy to find in spring and they are difficult to transport in cars.

The other thing to note is that they are usually replaced every year, so it is an annual cost. The soil in my garden is used for many years and cost nothing.

No Digging Required

This is a valid point point. But if you use traditional gardening and follow best practices for maintaining healthy soil, it also has no digging. I have not dug my vegetable garden for 15 years. I do dig a small hole to plant seedlings, but you have to do that in straw bale gardening as well.

This is not a valid benefit.

They Generate Their Own Warmth, Extending the Growing Season

When you condition the bales, you do get heat from the decomposition process. The following chart is published in Gardening with Straw Bales, by Dustin Blakey, University of California, Cooperative Extension.

You can see that there is a huge increase in temperature during conditioning. At the two week mark, the temperature drops to just above day-time air temperature. This second phase can last from 20 to 37 days, after which no extra heat is produced.

The above data is probably from California, were the author is located. The low night time temperatures are all above freezing in early April.

It is not clear what this chart would look like in colder zones and how quickly you can start the conditioning process. In this report for a northern garden (April 20), the decomposition process did not start due to cold temperatures.

In order for this technique to allow you to start earlier, it needs to be started about 4 weeks before your normal planting time. Two weeks for conditioning and two weeks to get an early start. I am not convinced that the composting process will occur that early.

The inside of the bales does stay warmer than air temperature and this may allow plants to grow quicker, early in the year, but this will only work for cool season crops. If you plant tomatoes in warm straw, and you get a frost, the tops will still be killed off. The bales do not keep the air above them warmer.

Since there is no heating after about a month, straw bale gardening will not extend the season into the fall. In fact, since the bales are above ground, they can be expected to cool down sooner than the ground.

Straw Bale Gardening Lets You Control the Nutrients

Besides the fertilizer you add, the nutrients will come from the straw. I don't see how you control these?

As far as the added fertilizer goes, you can also control the fertilizer you use on soil.

Instant Raised Bed

I guess this one is true if you compare making a raised bed to a straw bale gardening. But when compared to using traditional soil, I see no benefit. In fact you have to make the garden each year.

Even a raised bed will last for 10 years. How does that compare with annually hauling straw bales for 10 years?

As I have discussed before, you can easily make a raised bed without walls in a very short period of time and it will last forever.

Garden Without Soil

Even in straw bale gardening this is not always true. Many add some soil or soilless mix before planting seedlings, and you need to add soil on top for germinating seeds.

I really don't see much benefit for gardening without soil. One person did claim that it saves them from washing the vegetables!

Less Bending

This one is true. The top of the straw bale is much higher than ground level and this would be a benefit for some.

What happens when the pea, bean or tomato vines get to be 8 feet tall? When grown in the ground I can still reach the fruit, but if it started 3 feet above ground level, it is now at 11 feet and I need a step ladder.

There may be some benefit here.

Eliminates Soil Borne Diseases

This is a common claim and it seems quite reasonable. No soil, no soil-borne disease.

But one evaluation, growing tomatoes found that even in straw bales, the tomatoes got Fusarium a soilborne disease.

Some people place the bales on top of plastic separating the straw from the soil. This may help reduce soilborne diseases.

Mulching the ground will also reduce the transfer of soilborne diseases in traditional gardening.

Works Were There is No Soil, or Soil is Contaminated

Straw bales are used on driveways and concrete, where there is no soil. They can also be used on contaminated soil, or soil with high salinity.

Straw bales hold water and nutrients better than very sandy soil and may be a good option in such conditions.

This is a clear benefit to those who don't have soil that can be used for a garden.

Downside of Straw Bale Gardening

The above lists some positives, but there are also negatives.

Starting The Garden Over Annually

Spring is here and all I do is walk out to the garden, and plant my pea seeds. The garden is ready to go. I removed the straw mulch in fall so the soil heats up quicker in spring. I can plant a short row of peas in 5 minutes.

With straw bale gardening, I have to drive to get the bales, haul them to my garden, set them up, condition them for 10 days and add soil on top. It is then time to plant my peas.

I also have to drive to get my straw mulch, but it usually lasts several years. I have a truck so moving them is easy, but most home gardeners would need to get the messy bales into their cars.

More Frequent Watering

The proponents of straw bale gardening don't really mention the extra watering, but people who have tried the system report that it needs a lot more water than a normal garden – one report recommends watering twice a day. This is just extra work even if you add a drip system.

Mulched soil needs much less watering, reducing the work and cost.

More Fertilizer?

It is not really clear how often you need to fertilize the bales. Some don't mention it and say that the decomposing straw provides the nutrients. Others casually mention that some extra fertilizer is required. Some people say that you have to fertilize weekly, pointing out that you are essentially growing in a soilless mix that provides no nutrients.

A lot of this may depend on how much you water and how much rain you get. If you water a lot, it will wash nutrients out of the bale just like any container garden. In that case you need to fertilize constantly and especially after heavy rains.

I usually don't fertilize my vegetable garden. I might add some compost or manure as a mulch every couple of years. Fertilizing weekly certainly is a lot more work and expense.

Killer Straw

Straw may be contaminated with persistent herbicides like Dow Chemical's Clopyralid. This is a type of herbicide that is not broken down by composting. It's not clear to me how common this problem is, but it is a real concern.

What the Science Says

Rice straw is a waste product and research has been looking for a way to use it. Positive results were seen when growing strawberries in rice straw. Diseases were lower, the pH ranged from 5.5 to 6.5, less alkaline than the local soil, and crop quantity and quality were good. Similar results were found for sweet peppers.

The use of solid fertilizer can result in salt buildup, resulting in poor growth.

Understanding Straw Bale Gardening

Based on everything I have read, I feel the following is a fair description of this technique.

It is routinely compared to container gardening. The straw on the outside of the bale forms the container, and the decomposing straw in the center is the soilless mix. This container is very porous and water evaporates quickly from it. The straw itself is hollow and tends to hold water, but this water may not be readily available to plant roots.

Like any other soilless mix, it does not hold nutrients very well and needs to be fertilized regularly.

Others describe it as a hydroponic system, with no soil to hold nutrients.

Traditional Soil Garden vs Straw Bale Garden

You would think that proponents of straw bale gardening would test their system and compare it to traditional gardening. How else can you convince yourself and others, that it's better?

I read many blog posts and watched numerous videos and found only one comparison and it was from someone who compared it to her raised beds. The straw bales never heated up even though they were treated with high nitrogen. The plants did not grow well, even though they added a drip system for watering. It was a complete failure.

This summer I will be doing a test, comparing straw bale gardens to my traditional soil garden. I'll condition the bales and then treat them the same way as my garden so see which system works best. Updates will be posted on our Facebook Group: Garden Fundamentals. In fall of 2020, I'll post the results as a new blog post.

Should You Use Straw Bale Gardening?

Straw bale gardening is more work, takes more water and uses more fertilizer than traditional gardening. If you are able to grow food in soil, keep doing it.

This technique might be an option if you have no soil, or your soil is contaminated, chemically or with diseases. In these situations, place plastic between the bales and ground. If your soil is very sandy and holds no nutrients or water, straw bales might also be a good option since it might reduce water use.

If you have these soil issues a raised bed is also an alternative. It is more work initially because you have to build the bed, but long term, it's less work. It also requires less water and fertilizer, and I think it looks better. For a short term garden, straw bales are a better option.