Sowing Seed of Zoysia Turf - The Weather!

Timeliness is critical in many parts of the Australian mainland for successful sowing of zoysia seed for a turf area.

Not too hot, and not too cold is a good theme.

In northern areas above the Tropic of Capricorn, it is,  in a broad sense okay to sow most times of the year, except for cooler highland areas and inland where nights can be awfully cold in those winter months........avoid them!  We also caution about sowing in most years after April [last year was an exception as it was still very hot at that time] as with cooling and shortening days, while germination and establishment will be okay, it is almost impossible to easily develop a lawn due to cooler conditions with development often delayed until the weather warms after August.

As a best practice guide, sow from early to mid August onwards, when days are warm [above 25C] and nights around 18 -20C, or more.

The amount and quality of light is also important, with the much shorter days prior to August also slowing plant development, even slowing germination as zoysia is very light sensitive at germination.  As days lengthen noticeably from August it provides a boost to young zoysia growth, especially in combination with the arrival of warmer weather.

By October, storm rains are approaching and erosion can be an incredibly tricky issue on a bare site just ready for sowing, so some erosion management on the site is often needed, with a light soil mulch cover often a possible solution. However, it is warmer and germination is often a little quicker.

Ideally, a balance between August through September is mostly the best time to sow, striking a balance between warm enough but also when irrigation to establish the area is most effective and the weather is not so hot that applying water to a new area is often a problem.  It can be that there may even be water restrictions late in the dry season in some locations.

With suitable site management plans in place sowing through to December is certainly feasible, especially using hydroseeding that offers surface protection from the mulch placed on site with the seed.  Avoiding monsoonal weather months is sensible, unless there are very pressing needs, eg experienced landscape professionals.  Even then, more care is needed, and often inter monsoon periods may offer opportunities to get the planting done with less chance of failure.

Elsewhere around Australia in more temperate and sub tropical areas, later sowing is more sensible with September and October more likely to be the appropriate early sowing months.  Avoid late summer [March] and into autumn - there may not be enough time to fully develop the lawn before the cold weather arrives.  Remember that all sites do vary, even with some local minor quirks.

Help is available though,  to allow some strategic planning.........the BOM has excellent long term records for climate statistics for almost everywhere around Australia.  Get online and check your area.

You need daily average maxima to be near or above 20C and minima to be in the 10 - 15C range or more.  If your area is outside this range..........wait until it warms up more.  A prudent two week wait for warmer weather can pay off! 

While these are averages suitable for planning, daily records are also available for the past 24 months, giving a more accurate near term idea of temperature and rainfall trends.

If the weather is still cold........WAIT.  Zoysia is cold tolerant once established, but small young seedlings can be affected by cold weather.

Seed priming may help speed germination.  Read about it in a recent blog post.

Zoysia Boost for Golf Courses and Fine Turf in the Tropics - Professional Support

For northern Australia the most effective direction to seek out better options for turf quality and performance might just be to head offshore to Asia.

Enormous improvements  in turf management are occurring in Asia especially Thailand and China, with the emphasis in China on the southern warmer areas, where year round turf growth is possible.  Zoysia is already the preferred grass for many sportsfields used for football in the region.

The stand out grass for Thailand is zoysia - in a number of flavours, while China may require a few options depending on location and altitude, but zoysia is in the species mix.

More recently - early in 2016 - the organisation that is the effective comptroller of all things golf - The Royal and Ancient organisation has been sponsoring a series of seminars around Asia to enhance course management, with a number of distinguished speakers both from within and outside of Asia.

Seminars have been held in Beijing, PRC and in Thailand, both in March 2016.

Both have some relevance to Australia, but the one in Thailand offers better guidance for areas of Australia that are north of  Brisbane or Perth, including Darwin and Cairns.

Zoysia turf gets a big plus for Thailand and may offer a lot of potential for these similar areas in Australia.  And that includes domestic use as well as commercial areas - sportfields, golf courses and other managed grass sites.

Zoysia is strong in a number of areas relevant to current directions of concern for turf management, offering less water and fertiliser use as well as reduced disease incidence.

Zoysia matrella was 22% more efficient in water use and 25% more efficient in N use than couch. It does not require as much water or nitrogen to produce a dense sward and many courses can be operated on much lower inputs.  However, potassium can be often required in areas where clippings are removed.

A case is also made for using tropical carpetgrass in densely shaded areas eg under trees where it continues to show how it is the stand out performer in shade.

A more detailed overview is available here - www.randa.org/Thailand and there are nine free downloads available for those interested in golf course management, with zoysia turf a major discussion point.

These offer some very thoughtful ideas for anyone involved in turf management across north Australia.

And of course we can assist you with professional support, more information and seed of some high quality seeded zoysia varieties - with Zenith outstanding  - which we offer,  a significant part of many of the newer improved sport turf areas in Thailand.  

[Unfortunately Compadre variety is currently unavailable in Australia - maybe it will be later in 2016].

Developing a Zenith football field 2015 at a Darwin school, sown by hydroseeding.

     

Improving Germination Speed of Zoysia Seed - Seed Priming

When I first started research and development on zoysia the germination of the seed was a very tricky process.......low germination was common, especially with fresh seed.

Then a few scientists, including myself, began work to see if this could be improved.  Some work on related species showed that quite a few tropical grasses had tightly oppressed covers [glumes] around the seed [ caropysis], and that removal or damage that allowed moisture to penetrate improved germination.  Zoysia also exhibited this trait, and germination could be improved by piercing the glumes.  It worked in the lab, but a practical larger scale option was needed.

A process devised by a Chinese scientist showed that seed treatment with potassium hydroxide was effective in dramatically improving germination as it seemed to both soften the hard glumes and allow water to penetrate as well as overcome dormancy in the embryo.

This then became a commercial treatment, and is used today.

Light is also required and best germination in the laboratory is achieved with light [ and remember that seed is sown very close to the surface for that reason] -   no light and germination is much lower in the lab.

The other technology that relies on the inherent physiology and biochemistry of the germinating damp seed is a technique known as seed priming.  

Short term wetting of the seed starts the physiological and biochemical processes leading to germination........but if you then dry the seed along the way.....that process stops.  When you re-wet the seed, the process continues,  but restarts from the point you redried the seed, so the second time germination and seedling emergence process is much shorter.

For zoysia these processes are now being looked at  as a means to reduce the time from sowing to emergence, which can be normally up to 14 or more days, especially in cooler conditions.

You can prime the purchased seed ie the seed ready to germinate as having been treated to soften the glumes - overnight is currently recommended - in water.  Then the next day the damp seed is washed and spread out and dried in the light or even sunshine which provides a light stimulation.

This technique is now being recommended in the US for improving the time between sowing and seedling emergence.

While exact times and water temperatures are not stated in technology leaflets, the recommendation is a dark period soak eg overnight followed by draining and then drying out in light / warm sunshine.  I would be cautious about the temperature of tropical sunny days, but the principle seems clearcut - with this recommendation by one of the major seed producers of zoysia seed in the US.

Once the seed is dry, it is then sown normally, with an expected shorter time to germinate in the field. This potentially is a great boost in agronomic management options including irrigation, and allows seedlings to be established in the field much quicker.

We have not evaluated this here in Australia but the scientific principles are sound and broadly work for a range of other species, although timing of the soak period does vary among different species.

If you try the technique we would be interested in hearing of the experience.