In rose growing water is the most important factor for good growth and flowering. It is obvious that any material that helps conserve moisture in the soil would also help to grow good roses so mulch is essential.
Mulch can be anything from slabs of clay pavers through to the best mulch of all, Lucerne. So long as the ground is covered by a material that will allow moisture to flow through yet reduces moisture from evaporating is fine yet there are degrees of efficiency.
On top mulch is Lucerne straw. This product allows moisture to flow through, if laid out thick enough will stop much of the water evaporation and will feed the soil with high levels of Nitrogen. Cost per bale varies but would be around $8.00 to $10.00.
Not too far below are Pea Straw and Bean Straw. These products are similar to Lucerne but at slightly lower levels. Advantage is a bale can be found for as low as $5.00 but normally $6.00 to $9.00 is normal.
One bale applied deeply enough should cover 8 plants or 8m2.
Our next levels of mulches are still organic material and moisture holders. These products are Old Potting Mixes, Soil Improver Mulches, Garden Compost and fine wood or bark chips. They can still keep moisture in the soil yet do not provide nutrient vital for healthy new growth of a rose bush. These products may need added fertiliser to add Nitrogen and other elements.
Next are hard products. These can consist of Scoria, Gravel, Coarse Bark and Marble chips. These products can maintain moisture in the soil but do heat up in the summer making evaporation occur quicker than with more organic material. One aspect of these products is there is no benefit to the soil so extra fertiliser must be added twice a year.
Our last products are not necessarily the worse, paving slabs. Although a solid slab of material sounds bad in fact it is better than the gravel products. It allows moisture to penetrate through the gaps between pavers and greatly reduces evaporation as moisture is held under the paver’s surface. I have seen a myriad of rose roots just under the surface of a paver when removed. Only major problem is heat build up so consider light coloured pavers and choose heat tolerant rose varieties.
Mulching in all Australian gardens should be compulsory as its benefits are enormous. There is a mulch type for nearly all gardeners and although I will always seek organic do put something on the ground to hold in moisture. I am not a fan of weed mat material under mulch as this stops worms from moving the material through the soil. If weeds are a problem apply mulches thicker and consult your garden centre for either pre emergent weed sprays or selective herbicides