Tony writes:
"Mulching is being promoted extensively as a solution to gardening problems. And yet I wonder if it is not the cause of many gardeners being unable to grow many Fynbos plants. I have heard of people who used to have great Erica and Buchu collections, and now cannot grow them any more. Even at Kirstenbosch, many species that used to be grown in profusion can no longer be grown in the Protea and Erica beds.
I suspect that part of the problem is the tendency to use mulch. Although mulch has many positive effects, some of these are in fact also negative. It suppresses weeds! But at the same time it suppresses spring annuals. If I expect nice displays of annuals daisies or heliophilas, I wont get them with a mulch – bare soil is essential. Mulch also contains many bacteria that help maintain the soil: among these are pathogens that affect susceptible plants. And mulch, unless purchased from a reputable dealer, also contains slugs, millipedes and other denizens of tiny seedlings."
So why don't fynbos plants like mulch?
Tony says it is because fynbos plants evolved with fire, and after a fire the soil is sterilized and there are no pathogens or animals to eat the seeds. All the seedlings grow in a sterile medium, and it may take years for pathogens to build up, by which time the plants have set seed and the next generation is safely stored in the seedbank. Add mulch, and suddenly there is a moist layer that helps the growth and spread of pathogens, such as Phytophothora root rot, a fatal problem to many indigenous plants.
Tony's garden is on Cape Flats sand. The good news is that our soil is actually self-mulching in effect!
"Every summer as it dries out the soil becomes hydrophobic. Bacteria effectively coat the grains with oily secretions which stops any water from being lost from the soil. Water loss – the main reason given for using mulches – is thus effectively provided by nature free of charge. This sealing layer lasts all summer until the heavy autumn rains wash out the oils and allow the soils to soak up the winter rains. Where new plants have been planted, keeping the soil wet by watering the plants prevents the sealing layer from forming allowing water penetration into the soil only around the new plants.
Don’t expect any nurseryman to agree with this - it is provided by nature for free –it cannot be sold at a profit like mulch!
I have no problems with growing ericas and buchus: I don’t use woody mulch, but rely on nature to provide the sealant effect for me. The soil provides no home for slugs and pests, nor does it assist with the spread of pathogens by not providing a warm moist covering during summer when most Fynbos plants are dormant anyway. Sure some sand does blow around and into my swimming pool. But it is a small price to pay for seeing ericas, buchus and proteas flowering in profusion, not to mention the spring annuals that abound. Of course mulch is needed in European-style gardens and for forest species. But anyone on the Cape Flats who wants to have an indigenous, waterwise garden and who uses mulch is wasting their money!"
A buchu bush in full flower.
