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In the past high quality seed has not been readily available. Remnant stand harvests are not reliable as purity and germination percentages are often low. A recent test by Native Seeds of some Wallaby grass harvested from a remnant stand showed not only around 15 other species included, but also only a 4% germination of the Wallaby grass present. Good knowledge of the ideal germination conditions has not been widely available and is only now becoming more widespread through groups such as the Stipa Native Grass Association and the SA Native Grass Resources Group.
It is often assumed that as native grasses are very hardy and able to withstand drought and other hardships that the seed will be able to establish on hard, dry soils with no attention whatsoever. Unfortunately this is not the case and our grasses require every bit as much attention as the exotics.
Indeed for many of our grasses seedling recruitment is a relatively rare event and only occurs when conditions are absolutely perfect. This may be as infrequent as one year in ten when the lucky co-incidence of plentiful rainfall, appropriate temperature and sunlight are able to promote a flush of germination of the desired grass.
There are a number of factors that contribute to a successful result when sowing native grasses.
1. Have good weed control prior to sowing
Native grass seedlings are slow to establish and will not compete well with many exotic weeds which establish far faster and spread more rapidly.
2. Have good soil preparation at sowing
The better the soil to seed contact that is maintained, the higher the rate of germination of seeds. So a fully prepared seedbed will always give higher establishment rates than an unprepared or partially prepared seedbed. Even if the area being sown is very small, then a well prepared seedbed will yield better results
3. Sow them at the most suitable time of year
For all species there is an optimum temperature for establishment. It varies from species to species but usually it is from autumn to spring for cool season species and from spring to early summer for warm season species. The exception to this comes when irrigation is available as this then allows the sowing of cool season species in summer (albeit with much more effort). The key factors we have found are firstly, to sow the cool season species when moisture can be guaranteed to remain around the seed for 3 to 4 weeks after sowing, and secondly, for warm season species to focus on times when temperatures are above 25oC and try to provide a wet-dry-wet watering regime with pronounced periods of dry soil conditions.
4. Sow with appropriate equipment
The most suitable equipment is that which sows the seed to the preferred depth (usually 10 to 15 mm or about ½ inch) and which can meter it out regularly and evenly. With our new pelletized seed becoming available almost all pieces of conventional equipment can sow native grass seed successfully.
5. Apply irrigation if necessary
This might seem odd for native grasses, but they do respond to irrigation or rainfall at appropriate times. It may be that for some high value jobs it is best to establish the native grasses with temporary irrigation systems that are removed once the grasses become established.
6. Maintain good weed control through the early seedling stages of growth
As stated earlier native grass seedlings are not usually strong competitors against weeds. They are normally tolerant of broadleaf herbicides once they reach the 5 leaf stage so this method can be used for broadleaf control. Grass weeds can be more difficult, but the slow growth rate of the natives can be of some benefit here as wick-wiping of the taller growing exotics can be quite selective and mowing to remove the seedheads of annuals can reduce the number of seedlings in the following year.
7. Be patient
Please be patient. These grasses are wonderful long-term competitors once they are established, but are slow to get established and have many slow growth stages during their development. Frustration will set in at various times, but if you can be patient, the results will be there.
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