Growing Vegetables and Flowers in Straw Bales

 If you have a small yard or prefer not to bend over to work a garden, consider growing your flowers and vegetables in bales of straw.      

Straw bale gardening is catching on across the country and many people have found it the perfect way to grow vegetables and flowers in their yard.  Basically, gardening in straw bales is as simple as purchasing bales from a local farmer, setting them up in the spot where you want them, soaking them with water, and then poking your plants right into the bales.  Sound too simple?  Well, I may have over simplified the process a little, but gardening in straw bales is still pretty easy.

I am not talking about outlining the garden area with bales of straw and then filling in the space with a garden soil mix.  That is a totally different garden system.  I am talking about growing plants in the bales themselves.

To successfully garden in straw bales, it is necessary to start with a fresh, solid bale of straw.  Straw is defined as the left over stems of wheat, barley, and other grains after the seeds are harvested.  The straw is generally baled and sold for livestock bedding, mulching, construction, and other uses. Bales for gardening can be purchased from local grain growers.

I would not recommend just any straw. The first requirement is that it must be clean and without weeds or other litter.   If there are weeds in the bale, the bales  may also be infested with weed seeds and you just do not want that kind of a hassle.  The bale must also be bundled up firm and tight.  A tight bale will lose less water through evaporation and will give better support to the roots.

Some bale gardeners warn against using hay bales because of the danger of weeds but most of our hay in Pinal County is of pretty good quality so weeds concern me less than the heaviness of the bale.  I would stay away from old abandoned bales of any type.   They will not hold water as well as fresh bales and probably would not hold up well in the garden.

Here at the Cooperative Extension office, we have been experimenting with wheat straw bales.  We really do like them for all of the reasons mentioned above, plus they are relatively easy to find locally.  I would like to experiment more with alfalfa hay, barley, and maybe oat straw if I can find it, before I make any recommendations about using those types of bales.

How many bales does it take to grow a garden?  That depends upon how big you want your garden to be.  You could conceivably grow a garden in just one bale, but you wouldn’t get much produce.  Our demonstration garden at the Extension office is made up of two bales end to end.  Last year we grew vegetables and this is the year for flowers.  Our small garden has been so successful that we are thinking about a larger experimental garden with more bales.  The Master Gardener volunteers stationed at the Maricopa Agricultural Center in the City of Maricopa have a demonstration made up of six bales stacked side by side.

A typical bale is about four feet long and will generally support two tomato plants, three peppers and one to two squash plants.  Flowers can mostly be planted a little closer together but in ours, we have three sets of plants growing in one bale.  Using these guidelines you can estimate how many bales you will need for your garden.

Bales can be arranged in whatever pattern that best fits your needs.  They can be set singly in various parts of the yard, lined up end to end, or placed side by side in one location for more surface area.  The arrangement of the bales is a matter of taste and preference.

When considering bale placement, you will want to consider the issue of water.  The more surface area exposed to the air, the greater the loss through evaporation.  Single bales, and bales lined up end to end, will generally require more water than bales that are packed closely together side by side.  To prevent or at least greatly cut down on evaporation, many have found it beneficial to cover the outsides of the bales with plywood, metal roofing sheets, or black plastic.  The top of the bales can be mulched with compost to help cool the bales and prevent water loss.

The next question is whether to arrange the bales so that the strings on the bale face out to the sides or up and down.  While both arrangements work well, I like to stand my bales on their sides, so that the strings face out and not up and down.  This arrangement makes it easier to insert plants into the bale.  Also, water tends to soak down through the bales easier because the cut ends of the straws in the strings-out arrangement are pointed up and water follows the straws down into the bale more easily.

Selecting the correct site for the garden is also important.  You will remember that many vegetables and flowers do best in full sun while some require filtered or late afternoon shade.  Your final decision of where the bales will be placed will be dependent upon what you want to grow.  Give this a little extra thought before you soak the bales.  Once they get wet, you really do not want to be pushing their heavy, dead weight around, I guarantee you!

Once the bales are in place, they need to be prepared for planting.  The first step is to soak them completely with water.  The easiest way is to pull the hose over and thoroughly soak them.  The addition of water begins a decomposition process inside the bales.  This breakdown is natural and will leave the bales inside with a loose array of fine mesh compost that is healthy for the plants.

Before irrigating, it is a good idea to add some nitrogen fertilizer to the bales to aid the decomposition process.  If you want to garden according to organic procedures, use two cups of blood meal or fish emulsion.  Spread it on top and the water will take it in.  Be sure not to over soak the bales so that water runs out the bottom.  Your fertilizer will leach out of the bale with it.  If you are not concerned about organic gardening, one-half cup of ammonium sulfate will do the trick.

Once the bales are prepped and soaked, wait about two weeks before planting.  The break down process will generate heat and we want the bales to cool down inside a little before we put the plants in place.  This will result in less damage to the new plants.  However, I must say that we did not do this in our demonstration garden.  We just soaked and planted.  The tomatoes and strawberries did just fine.  I am not saying that this is the best way to do it but we got away with it.

The next step is to figure out how to keep your garden wet.  A drip system is a good way to go, especially if it is hooked to a timer that will turn the water on and off.  Otherwise you will need to be handy to water every day, especially during the warmer months.  I hand carry water to our two bales in a watering bucket.  I just have to remember to do it every day.  On the days I am gone, I have to find a willing volunteer.  Otherwise, the plants will suffer.

Because the bales do not provide a lot of nutrients, we need to fertilize on a regular basis through the growing season.  Many of the required nutrients are only needed in small amounts and come to the garden free of charge in the water and from the dust storms that blow through.  However, nitrogen, phosphorus, and potassium will need to be added regularly.

For straw bale gardening, I select a complete fertilizer that will add all three nutrients.  A complete fertilizer is one that has a number in all three spaces on the fertilizer bag, like 16-16-16.  The fertilizer must be worked into the bale with a trowel, digging tool, or fingers.

Once the bale is prepped, it is time to plant.  I recommend transplants, or plants that are already growing, because they are easier to handle and results are quicker.  They  can be set into the bale in either of two different ways.  You can excavate holes down into the bale and fill the holes with composted organic matter or straw, or you can gently pry apart the sections of the bale and insert the roots down into the bale. When planting, carefully remove the plants from their nursery containers and gently insert them into place.  Cover the base of the plant with a layer of compost added to the top of the bale and you are done.

If, during the garden season, you begin to see weeds sprouting from the bales, they can be gently removed by hand.  Just pull them out.  Don’t try to spray them with weed killer.  Check for insect and mite pests like you would do in any garden.

How long do the bales last?  We are on our second year here.  After the first year I found that the entire inside of the bales were composted down into a loose layer.  To make sure that we had good root support, I filled the hollow gaps with potting soil.  Our second year crop is doing just fine.  Although possible, I doubt that we will get a third year out of the bales.

If you are dealing with difficult soil problems, or are physically unable to work in a regular garden, the straw bale garden may be the perfect way to grow healthy vegetables and colorful flowers in your own yard.

If you have questions, you can reach one of the Master Gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande.  The telephone is (520) 836-5221, extension 204.  The author’s email address is gibsonrd@ag.arizona.edu.

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Rick Gibson
Extension Agent, Agriculture
University of Arizona Cooperative Extension
820 E. Cottonwood Lane, Building C
Casa Grande, Arizona 85222
Voice:    (520) 836-5221
Fax:    (520) 836-1750
email:    gibsonrd@ag.arizona.edu