Just add water

Sunday, 16 February 2020

One of my borders that has come back to life over the past week

Just like adding water to those weird 'sea monkeys' advertised on the back cover of comic books in my youth (what were those sea monkeys??), the rain we received last weekend in Sydney has brought our gardens almost instantly back to life. Parched lawns that were on their last gasp only two short weeks ago during one of the horrific heatwaves, have now sprung into mad, vigorous growth. Lawn mowers, in hibernation over summer, have suddenly all been fired up in a cacophony of roars, and the fresh, sweet smell of cut grass once again fills the air. If ever there was any doubt as to the need for sufficient water for optimum growth, the proof is in. Our garden plants, seemingly dormant for the past few months, have surged into jungle-like growth, expanding in every direction and making up for lost time. Street trees and plants in public parks are also rejoicing in the rain; so many of these were doing very badly through December and January.

Bizarre fungus that appeared this week in a pot plant in Sydney; photo by Lyn Cox

The earth is saturated. Enormous weeds have appeared overnight. Strange fungi are flourishing in pots, in the ground and on plants, reminding us that Sydney never is actually going to turn into a Mediterranean-style climate and we must stay vigilant to ensure we have good drainage in our gardens and avoid planting specimens that dislike humidity. Because humidity, one of the trademarks of the Sydney summer, is back with a vengeance and will kill off susceptible plants through the growth of fungal diseases, especially in plants with a low basal rosette of leaves. Check your plants for signs of such fungal diseases and put them into the green bin immediately, and remove some of the surrounding soil, which might harbour spores, and get rid of it too.

Salvia Amistad

This seems a perfect time to do some light trimming of your plants, especially those that have been burnt or have rangy, straggly growth. I have cut back some of my long-flowering salvias, such as 'Amistad', which were looking rather gaunt, and am hoping I will get some new growth fuelled by the abundant levels of moisture in the soil. I am also planning to apply some organic-based fertilisers such as worm castings at this time, watered in well.

Grey-water tank for installation

Despite staggering rises in Sydney's dam levels, currently Level 2 watering restrictions are still in place, and may remain there. Despite our euphoria about the rain (which I must also mention caused a lot of damage and suffering throughout our city last weekend), it is very likely that there will be drier times ahead and we need to plan for this. We must not ever forget the summer we have just had! One suggestion is to apply a thick layer of organic mulch to your garden whilst all the moisture is in it, to keep it there for as long as possible. Consider investing in a rainwater tank if it is feasible in your garden. The joy of knowing that our tanks have been filled to the brim was one of the highlights of the rainfall, so we can cheerfully (and legally) hose our gardens when the heat kicks back in. Ironically enough, the grey-water system we plan to install arrived just the day before last week's wet weather, but we hope it will serve us well in the future when times get tough again, as I am sure they will.

Water pooled under my Liquidambar tree last week

I noticed how water pooled between the large exposed roots of my giant Liquidambar tree, and took a full day to soak away; this made me wonder if there are simple ways we can slow down the flow of water across and away from our gardens during rain events. It could be madness but maybe something could be rigged up to hold water for a while to allow it to soak in over time. This is the idea behind rain gardens, as well as the swales and contours used in agricultural settings to hold water on properties that would otherwise rush over the ground and into rivers. I'd love to hear from anyone who has ideas on how this idea could be developed in a garden setting!

Rhizomatous begonia, polka dot plant and other groundcovers in a dense planting in my garden

Another point is the importance of dense planting in our gardens. According to a NSW Primary Industries Agfact Sheet: 'Falling raindrops possess energy that is dissipated on striking bare soil by breaking down soil structure and detaching and transporting soil particles. The detached particles typically form a surface seal that reduces soil infiltration rates and increases run-off. Plant cover protects the soil by intercepting raindrops, impeding run-off flow and dissipating the associated energy. Without adequate groundcover, up to 85% of the rainfall from individual storms can run off into creeks and streams rather than soak into the soil and be available for plant growth.' (Agfact P2.1.14, January 2005, p. 1). Food for thought, and not something I had ever really thought about before; and it adds another dimension to my previous blog on close planting. Run-off from our gardens can carry chemical fertilisers and pesticides into rivers, creeks and oceans; another good reason to avoid these chemicals in our gardens!