Friday, April 15, 2011

How do I prepare soil for my raised garden bed?

The Melbourne International Flower & Garden Show is over for another year.  I had to step back from our commitment to The Great Victorian Hanging Basket Competition (follow this link for a list of all the winners) this year, it is just getting too big. I have to say that letting go and getting a broader range of input was the best thing I could do.  Congratulations to Don & Jennifer Rickerby and their hard working RHSV team, especially Rod & Kevin. Thanks also to James Wall, Gardenworld and Andrew Jones, Poynton's of Essendon for the work they put into a spectacular display.

Although we reduced our commitment, the Hanging Basket Competition was still the focus of our own representation at the show. We supplied 6 Magic Square Gardens to dress the display along with 3 other gardens for the Tree and Shrub Growers of Victoria's "Kitchen Garden".  The response at the show and since has been enormous! Lots of enquiry and web hits. Plus a few questions that came up consistently, especially "What soil should I use in my raised garden bed?".

My immediate response is "this is a big pot so the ideal growing medium is potting mix". Quality potting mix is carefully formulated to manage water and air availability for your plants. We offer potting mix filled Magic Square Gardens but for many people working on a budget this is prohibitively expensive. I have seen top soil from garden supplies used quite regularly, but I have also been disappointed with the plant growth. Garden supplies spruik their favourite top soil but I worry that it is hungry and prone to holding too much water for vegie growing. So what is the best answer?

No Dig Gardening! Mix the top soil up with layers of straw and animal manure to create and ideal vegetable growing media in a box. So what do you need? One Magic Square Garden holds 1m3 of soil  so here's a suggested recipe for filling your bed on a budget and still getting a great result.

Quality Top Soil.               2/3 - 3/4m3
Sugar Cane mulch           1 Bale
Horse Poo                        1 Bag
Composted garden clippings and worm castings... if you have these available, use them liberally.
 I have chosen Sugar Cane mulch because it is available everywhere in convenient bales, lucerne hay is apparently the pick of mulching materials.  I chose horse poo because there is plenty of agistment arond here and bags of cheap poop available. Dynamic Lifter is very good and available everywhere. 

We're going to produce a layer cake in a box. Start with the mulch, put about 1/3 of the bale in the bottom of your box and add 5-6 hand fulls of manure. Fill the box to about half way with top soil then add another layer of mulch (1/3 of the bale) & manure, it's a good idea to water the layers at this stage to help settle them in. Use the rest of the soil which should leave about 10cm to the top of the box from the soil surface.  Plant your vegies in this soil and dress around them carefully with the remaining mulch.  Don't use any more fertilizer in this last layer, too much manure too close to the plants can cause burning problems. Osmosis and root systems will draw the goodness up so the plants can use it. You can side dress with maure once the plants have matured and they are looking for additional food while they put energy into flowering and fruiting.

Let me know how your garden grows so I can update this information.

Thanks also to Rosie Appleton and the Berwick Viewfinders Camera Club for the great pics from the Flower & Garden Show.


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