Sowing and Nutrition - for Seed Sown Zoysia

This question is a perennial one that is regularly asked by those developing a new turf area.  While there are some guides about how to sow seed, the nutrition aspects are not widely available particularly for conditions outside of the USA.  

Zoysia from seed is effectively established with modest nutrition – we suggest 2 applications each of 200g / 100 sq m of a good mixed NPK fertiliser with trace elements, applied evenly to dry soil before sowing and raked into the soil, and at 3-4 weeks after sowing which can be irrigated into the ground.  Suitable products include Yara Hydrocomplex NPK 12:15:10 [or similar as many blends are close to this] plus trace elements and iron.  Others potentially available include Crop King 55 and 88, Nitrophoska Blue and a range of other suitable all-purpose fertilisers used at sowing depending on availability at your local supplier.

Follow that by switching to a slow release fertiliser eg Scotts  - [ or other brands that may be available from many garden shops incl Bunnings and BigW in 2kg and 4 kg  bags, but do not use any with herbicide while the area is so young], applied at about 6-8 weeks  from sowing and thereafter at 12 week intervals in year 1 – you can use about one half of the recommended rate for zoysia – the recommended rate is broadly based for use on couch.  After that maybe 2-3 times a year is enough -August to October [depending on location], early March and [maybe in warm areas] May. for larger areas, sometimes a 25kg bag is a sensible buy - store it in a secure lidded plastic pail and it will be okay for several years. 

Slow release fertiliser is strongly recommended for all zoysia turf areas.  Avoid excess fertilising and non-slow release nitrogen fertiliser – that encourages thatch development.

If more green colour is needed for your turf – apply 0.5% - 1% iron sulfate solution [no stronger please] – great colour can be achieved but not too much growth! 

We strongly suggest additional potassium in September/October and March each year [ southern hemisphere areas] – use potassium sulfate [sulfate of potash] at 1kg / 100 sq m, and avoid muriate of potash.  This potash product is sold in 1.5 and 2.5 kg pails from many major garden stores and also is available in larger sizes [25kg] if required.

At sowing, a very light mulch cover can be helpful to manage and assist with holding moisture close to the surface during the vital early few weeks.  Light materials are best including sugar cane mulch and mature fine compost or similar, with a very thin cover helpful – no more than 1-2mm that holds moisture close to the surface where the seed is germinating.  

After sowing, irrigation during the day, for a few minutes each time, is needed to dampen the surface but not make it too wet.  As to the number needed - suggest 2-3 times each day at late morning and early afternoon as a start………but need to adjust as needed, and it will be temperature and wind dependent.  This can be reduced once seedlings emerge – some individual judgment is needed on this issue, as all sites and conditions are different.  The need is for SURFACE DAMP not SURFACE  DROWNING.

Seed emergence can be sped up with seed priming – soak seed for up to 36 -48hrs in warm [definitely not cold] water at around 20C eg and keep inside where it is warmer, then drain and lay out seed to surface dry in the sun next morning………..can speed emergence by a quite a few days [ see info from Pickseed].

Weeds can be troublesome at some, often older or renovated sites.  Make sure the weed is identified correctly before rushing to use any herbicide. Often repeated mowing will aid removal of the weeds as the turf species develops and strengthens often choking out the weeds. 

DO NOT use glyphosate / Roundup® or similar products on zoysia – it is quite sensitive to this type of product!  There are some products that may be useful; with an MCPA /dicamba mix often well suited for broadleaf weed control [one trade name is Kamba M – there are some others].  Try to avoid use of herbicides when the area is very young, unless you really understand what you are doing or have sought professional advice.  If in doubt ask us – there are often solutions available.

Prepare in advance, be organised at sowing and be prepared to invest time and effort then – it will be rewarded with a great lawn nearly always achievable [If in doubt, checkout the You Tube videos].  Most poor outcomes are traced back to problems at sowing and site preparation.

For larger zoysia seeded areas – eg over 1000 – 2000 sq m, often using hydroseeding may be a suitable option.  It works very well with the mulch used at sowing acting as a very good surface mulch and erosion management tool.  For smaller areas costs of cleaning equipment before hand  can make using hydroseeding too expensive, even though results are generally very good.

Zenith Zoysia Seed to Develop a New Oval in the Tropics - Part 4 - Maturing the Grass

It always take some time to develop an oval to the stage where it is getting ready to use.

Plants need to thicken and develop a dense sward above the ground surface while also developing their roots so they can effectively resist all the pressures on the grass that occurs during the playing of ball games or anything else planned for the oval  - it has to mature.

There will need to be regular mowing at about a 7-10 day interval - even more frequent in some cases - to help thicken the sward as lateral growth is encouraged, to fill any thin or bare spots.  Fertiliser is applied - normally at about 4 week intervals [ that is about how long normal agricultural type fertiliser can supply nutrients, particularly nitrogen, although other types [ phosphorus, potassium, trace elements] may be available for longer] for about 12 weeks,

Weed control is vital during this phase, to ensure the favoured grass is encouraged and impediments to growth removed.  Disease management and control may also be an issue in some cases.

In the period from around 45 days through to around 95 days after sowing the Zenith Zoysia area had a second application of fertiliser at about 8 -9 weeks [ 56+ days from sowing] and will be due for another at 12 -14 weeks, except this time it will be a slow release fertiliser, better suited to ongoing turf growth and with an availability period of 12 -16 weeks, thus preventing rapid growth, yet continuing to provide adequate nutrition for the turf for many weeks.

Weed control was instituted with several applications of herbicide.  The earlier applied residual herbicide continued to provide annual grass and some broadleaved weed control, but was boosted with two applications of a product that gives excellent knock down, but not very much residual weed control of broad leaved weeds - Kamba -M, applied at around 70 days after sowing and more recently at approximately 95 days from sowing.  Ideally the latter one would have been sooner, but a 48 hour dry period after application is needed for best results - and it continued to rain every few days!  Makes that a bit tricky.  The second application seems to have been very effective.

However, there have been issues with grass weeds.  While some grass weeds can be controlled with selective herbicides, the real culprit has been Bothriochloa spp plants - a particularly hard to control grass weed, and with few options for herbicide use.  The area did have a lot of these plants initially and were controlled with glyphosate before seed sowing, but the residual seed in the ground has germinated around the same time as the zoysia seed and slowly developed into a problem that requires hand removal.  The dense turf as it develops will eventually prevent most, if not all, future germination from the residual seeds, as well as the seed in the ground dying.  But in the meantime seedlings of it have to go...........  Resorting to hand weeding is almost inevitable in fine turf development, but it is labour and time intensive.  And requires many revisits to the same area to ensure it is all gone, as you can often miss small plants.

By mowing at 7-10 day intervals the weedy grass has time to put up a seed head between mowing periods, allowing easy identification, yet if removed in that 6-10 day time frame it is short enough to prevent any more seed development as full flowering has not started.  A real problem also exists in that the same species is all around the outside of the oval, and could easily re reintroduced to the oval area through mowing, especially if careless mowing of the oval surrounds is carried out.  Not an easy situation to rectify.  Although low levels are present initially, good progress in eliminating the Bothriochloa spp on the oval is progressing okay, but may require a few more weeding / mowing cycles, and ongoing vigilance.

Before mowing - 90 days from sowing

Before mowing - 90 days from sowing

Before mowing - 90 days from sowing

Before mowing at 90 days from sowing

before mowing - 90 days from sowing

After broad leaved weed control 98 days from sowing

Very effective broad leaved weed control at 98 days from sowing

At 98 days - Bothriochloa spp - grass weed in dense Zenith zoysia turf - note emerged seed head 7 days after mowing

Sowing Compadre Zoysia Seed - Starter Fertiliser

The starter fertiliser we suggest is Nitrophoska Blue , Yara Mila [ sometimes sold as Yara Hydrocomplex] , Crop King 55 or Crop King 88.  All are okay and have slightly different NPK blends, and different retailers sell them,  so you need to see what might be around in your area through Bunnings, Elders, Landmark etc.

Companies such as Lesco and Scotts which specialise in turf products and equipment, also have small prilled, turf starter fertiliser with some slow release nitrogen.  Quite good to use but can be more expensive and may be more difficult to source.

 

Commonly the NPK ratios are around 20: 12: 15, often with 5-10% sulfur as well, plus trace elements, for these starter fertilisers.

 

There are other brands as well, but many other brands are less well known and less available for smaller users.

 

Use what is available and attractively priced in your region.  These products are soluble fertiliser and can be mobile ie leach, and need additional fertiliser within about 4 weeks of application.

 

We recommend 2kg / 100 sq m at or before sowing, another 2kg/100 sq m at about 4-6 weeks [after emergence and when small seedlings are present] and then to switch to a slow release turf product at about 8-10 weeks, and then repeat every 12 weeks after that, until cooler months [say May or June].  From the next year in September / October restart the slow release fertiliser and repeat at 12 weeks intervals.  From midway in the next year, cease fertiliser application when cooler weather starts, then recommence with a 2 or 3 times per year schedule of slow release turf fertiliser from September /October,  omitting mid-summer and mid-winter periods. [more details on product in an earlier post] 

For zoysia use half of the recommended rate on the bag, so normally use about 2kg/100 sq m [ usual recommendation is 3-5kg/100 sq m, which is based around couch - do not need as much for zoysia.]

 

It is very important to spread fertiliser evenly.  Use a push type spreader or a small hand applicator for smaller areas.  Lightly water into the ground after application, aiming to avoid burning the small seedlings.  In hot weather, apply fertiliser late afternoon or early evening to avoid burning plants.

 

 

Which Fertiliser for Compadre Zoysia?

Choice of fertiliser is always a bit of a conundrum these days with so many types and blends available.

There is some benefit in using organic fertiliser for example pelletised chicken manure , or DPM - densified poultry manure.  It adds organic matter and some nutrients but the nutrient level is relatively low, and it can be more expensive if freight costs are an issue eg in rural and remote areas.  It can be short in some nutrients as well.  It can be useful if the turf is growing on light sandy loam soil or sand.

Conventional inorganic fertiliser is modestly priced, and there are blends that mostly meet criteria for use on turf, but all have generally rapid availability of nutrients and they can often leach quickly.  Because they are mostly readily available you get rapid lawn growth = more mowing, then the nutrients disappear and you need more, maybe in 4 weeks.  And more mowing still!!  Not the best choice at all.

Slow release turf fertilisers are ideal.  They release the nutrients, especially the nitrogen, over an extended period [often 10 -16 weeks, but longer release period products are also available].  The result is less mowing, a better appearance lawn and better availability of plant nutrients.  Many are available in small bags through garden stores and chain shops - 2-4kg sizes, but for best cost effectiveness, buy a 25kg bag and store it in a sealed plastic bin, in the bag.  It will stay usable for 2-3 years at a lower cost.

Domestic Compadre zoysia turf - Darwin area, 20 weeks after sowing seed

The blend is important, and a general use product has around 15- 25% nitrogen, 1-3% phosphorus and 10 -20% potassium, plus some sulfur [ 5-10%] , trace elements if possible, and most importantly a small amount of iron - 0.5 -1.0%.  The iron boosts the lawn colour to a lovely green, without much effect on growth.

The potassium level is important, particularly in wetter and /or warmer climates.  Potassium is mobile so can leach out in wetter periods but its role is to strengthen cell walls and provide better stress resistance, hence the need for decent potassium levels in hot weather.  Modest to low phosphorus is better, assuming the soil does have a reasonable base P level.  With more P you tend to promote legume growth [ essentially a weed in turf].

For zoysia, which is not a prolific growing lawn, the iron is especially important as mowing is less frequent and that delightful green colour is impressive for many weeks, without being cut off.

The other question is always how much.  We suggest halving any recommendation on a fertiliser bag if applying to zoysia, of any type.  Many products recommend 3 - 4kg/100 sq m for slow release fertiliser for eg couch lawns.  For zoysia - 1-2 kg/100 sq m is usually enough.  The exception may be on new lawns less than 1 year old, when you are building up a store in the soil when the recommended rate may be okay in peak growth periods.

And of course in cooler months - applying fertiliser is really not needed as the lawn is not growing very much anyway.  And not too much in wet summer conditions - it means more mowing!

If one of the common types of slow release turf fertiliser is used with a nominal 12 week release period, for zoysia of any type - twice a year is okay, once established.  Nominally apply in Autumn and Spring [or late wet season and late dry season].

The fertiliser question is always tricky and individual areas may require a slightly modified approach in areas where particular nutrients are in short supply or even may be in abundance.

But the above maxims apply in many areas, and are a suitable starting point.

Enjoy your zoysia turf.....and apply a bit of TLC!!