Spring, and thoughts turn to mulch

Garlic May 2014I noticed yesterday that the stonefruit trees have budded and are about to unfurl. Despite little winter rain, the perennials (rhubarb replants, globe artichokes, strawb runners) are beginning to move again  and the annuals (garlic, broadies, greens) are adding bulk and height. Frances’s natives are on the move; a grevillea near the igloo is flowering.

Central Victoria – or Newstead at least – has a short, but very sweet, spring. Blink and you may miss its flush. Temperatures are still cool and the frosts still potent, but spring is just about upon us. Time to get the last of the ‘winter jobs’ done and think about the prolific time to come. Including the weeds!

It’s also time to think about mulching. Mulching bare soil is a good practice to:

  • prevent weeds from germinating and establishing,
  • conserve moisture,
  • protect the soil surface from crusting and drying,
  • encourage worms and microbes to hang about in the top part of the soil longer,
  • insulate and protect plant roots.

One disadvantage of mulching, particularly with straws is the slugs and snails and slaters that harbour under it. We have found they hide under the straw mulch, come out at night to feast and go back in hiding for the day, sated and happy. But as temperatures rise, the pesky slugs and snails will lose their upper hand over the plants (keep up protection with the copper tape though).

fog and frostMulch isn’t just mulch. Each type has different properties. The loose, fibrous, straw mulches can accentuate frosts because they create greater temperature differences at the soil surface. This isn’t a problem for cold loving crops like parsnip, kale, brussels sprouts, cabbage, kohlrabi, garlic and onions, but more tender plants can suffer. This time of year darker mulches will absorb warmth and benefit soil and crop metabolism (eg. rock dust, darker materials). In summer the lighter colors will reflect light and heat, but still insulate.

Beware of mulches that are very high in Carbon and ‘fresh’ (eg.spelt hulls, wood chips, or sawdust). They can ‘tie up’ any available nitrogen, preventing plants from getting it and causing starvation, or at least Nitrogen deficiency. Mulches that have some some nitrogen component are best (eg lucerne, pea straw) as they will add to the soil as they rot, besides the soil cover benefit. They are usually more expensive though. I avoid sugar cane mulch because of the ‘mulch miles’ and packaging, plus it is fairly lightweight and too quickly assimilated into the soil or blown about by the wind.

Look for certified organic and biodynamic. Conventional mulches will have usually been grown with synthetic fertilisers and usually lucerne will have been sprayed for pests such as red legged earth mite and weeds (and look for second or third cut lucerne – less weeds, usually).

digging in green manure of spelt, lentils and mustardAnd there’s always living mulch. Lucerne grown around fruit trees can be cut and placed around other garden areas or on the trees themselves. A ‘good bug mix’ of clovers, lucerne, flowers and herbs is also a highly effective living mulch. You can also grow your own version, say a mix of wheat, rye peas and mustard, Cut it off at ground level around flowering or just before, mulch with the cut portion and dig in the residue, to get double the benefit. Herbs such as comfrey or nettle make a great mulch. A budget version is just to cut and shred any crop residues or non-invasive weeds and put them on the soil surface.

Happy mulching.

And see you on Sunday at 10am for our get together with Jinette to talk about the garden.  Plus, the CWA are coming to visit the garden on September 10 – more news on that shortly.


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