Strawbale Growing Systems

The strawbale growing system is one that has been in practice for many years. If you like the idea of growing warmth-loving plants such as tomatoes, melons and cucumbers, then strawbale growing system will definitely be of interest to you.

Two Basic Strawbale Systems

Strawbales work as a soil replacement because a wet strawbale provides everything that a growing plant needs in abundance – air, moisture, and a slow release of nutrients. However, damp and wet strawbales that have started the decomposition process also generate a fair amount of heat, and it’s this that makes using strawbales perfect for plants that are most successful in warm or humid conditions.

If you’re keen on using strawbales as a no-dig, so-soil growing alternative, there are two basic approaches. Firstly, you can actually construct a ‘greenhouse’ from strawbales; use the bales in place of glass and bricks, stacking to a two or three tier structure and covering with a makeshift polytunnel roof.

However, this article focuses on using the bales as the growing medium inside your greenhouse – ideal if your greenhouse has solid concrete or paved flooring. Strawbale growing is also ideal if you have persistent soil-borne disease problems, or if space is at a premium. The other strawbale option is to actually construct a ‘greenhouse’ from strawbales; use the bales in place of glass and bricks, stacking to a two or three tier structure and covering with a makeshift polytunnel roof.

Using Strawbales in Your Greenhouse

If you would rather opt for the smaller-scale option of using strawbales in your greenhouse, then the good news is that this method of greenhouse growing is actually quite easy and straightforward. However, what you’ll need to know beforehand is that the preparation aspect of strawbale growing can be a little lengthier than growing in soil. It’s vital that you create the right conditions for your plants to grow; otherwise you could be looking at a less than successful outcome!

Bear in mind that before you begin preparing your strawbales for growing, the ambient daytime temperature should ideally be above 10 degrees C/50 degrees F. This is partly because decomposition to take place at the right rate, it needs to be sufficiently warm. You also need to get your strawbales in place, because once they’ve been watered they’ll be significantly heavier than dry bales. If placing the bales in a greenhouse or on diseased soil, you can line the bottom with black plastic, or used compost bags to stop the roots growing through the bales. This also helps to retain moisture in the bales.

What Type of Straw do I Use?

It may seem a strange question, but the type of straw will affect the heat output and growing success rate. Wheat straw tends to be most popular, as other types of straw tend to decompose much faster and may contain more weed and grass seeds.

You should also make sure that, as with growing in pots, you have growing canes to stake into the strawbales to support your growing plants.

Prepare Your Strawbales

To prepare your strawbales, you basically need to do two things – water them for around 3 or 4 days, and fertilise them. You can use liquid compost extract if available in your garden (although the smell often isn’t too pleasant!), or another ‘free’ alternative is human urine – possibly an easier method for men, and also dependent on the privacy of your greenhouse!

Another more conventional option is shop-bought blood or bone meal, or failing that, organic fertiliser. If dry, mix the organic fertiliser with water and water onto the bales. After a week or so you can add another helping of general fertiliser to the bales, and monitor the heat production. The temperature should initially rise, but once it falls to around 38 degrees C/100 degrees F you can begin planting.

Growing Plants in Your Strawbales

It’s probably best to limit the number of plants that you grow per bale. Three small plants or two medium plants will usually suffice. You can dress the top of the bales with a general compost, and make two or three holes in the top in which to plant. Place and stake your plants, and water in as usual. Provided the bales are damp enough, you will probably find that your plants are more stable and less ‘leggy’ than plants grown in grow bags.

You can also do some companion planting to help ward off pests – nasturtiums and marigolds should all grow successfully along the edges of the bales and can add an attractive touch too! Once you’ve finished with the bales, simply break them up and add them to your compost heap.

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