DON'T PLANT TREES ON PLANET ARK'S NATIONAL TREE DAY

July 27 is Planet Ark's National Tree day but it's the wrong time of year to be planting trees in south west WA. A date in late July was selected by Planet Ark more than 10 years ago to best suit tree planting in eastern Australia but it's a totally inappropriate time of year for most of the south west of this state.

I make this call in my capacity as an environmental consultant based in the south west since 1976. I'm also president of one of rural WA's largest and most active conservation groups, the Busselton Naturalists Club.

The end of July is mid-winter in our Mediterranean climate and it's usually the coldest part of the year. Plants put in the ground in late July will generally just sit there and hibernate, waiting for the warmer temperatures of spring in September and October.

They then just have a few weeks of warmer spring weather to get their roots deep enough into the water table to survive our hot summers.

So the best time of year to plant is right now - June - after the first heavy winter rains have fallen and while the ground is still warm.

Planting in late July also means that seedlings miss out on the 4 to 10 weeks of root development that could have been achieved if they had been planted in the period from mid-May until the end of June. These few weeks may be the difference between life and death for the seedlings when the rains stop in spring and our hot dry summers cause water tables to drop by a metre or more.

If seedlings can get their roots down into the water table early in the growing season, they have a better chance of following the water table down into the subsoil as summer evaporation takes hold.

Spring is an important time to plant seedlings into wetlands, as the receding water levels allow plants to be placed into damp but freshly exposed soils, allowing good root development to sustain the seedlings over summer.

In heavier soils in the wheatbelt where soil moisture can persist late into the spring, plantings in late winter can make some sense.

But the sandy soils of the Swan Coastal Plain where most West Australians live dry out very quickly in springtime, so a July 27 planting is risking the loss of most seedlings.

I've previously spoken with Planet Ark about how unsuitable their National Tree Day is for much of the south west of WA. I've suggested that they should select a more suitable date in late May or June and call it WA Tree Day or similar but my pleas have been ignored.

While I was the member for Vasse, I also approached the state government and urged them to promote Arbor Day as the south west's tree planting day. The Department of Environment and Conservation's website doesn't show when Arbor Day was scheduled for 2012 but it's usually in middle to late May or early June which is often ideal for most of the south west.

I'm urging school and community groups, as well as individuals, to get out and get dirty now, with planting through to the end of June preferred.

I'm also urging people to buy local plants that are well suited to our climatic and soil conditions.

And buying from local nurseries makes a lot of sense, especially from the Geographe Community Landcare Nursery on Queen Elizabeth Avenue who specialise in seed collected locally and whose staff can provide excellent advice on the plants best suited to your garden or farm.