Cutting costs on the seeds you use is a dangerous game to play
Let us assume that we are renovating a surface on a golf course, it could be a green, tee, fairway or even a traffic route … each has its own set of problems, although the desired end result is usually the same – to establish a full cover of grass or improve the quality of the grass surface. In each instance the process of approaching the works needs to be the same, which starts with a simple question: How do I optimise my chances of reaching my objective?
When undertaking seeding there are some additonal questions to consider before deciding on aeration tactics:
1. Which aeration technique will prepare the ground to ensure the best conditions for seedling grasses to establish after germination?
2. Which aeration technique will give the best chances of seed contacting the soil and germinating?
(The emphasis on the above is the order in which these questions are asked. Too often it is easy to see greenkeepers adopting the first question without a thought to the second, leading to failure of the seedling grasses as they establish in unfriendly ground.)
3. When should I carry out each operation?
4. How am I going to follow up the aeration and seeding works?
Let’s look at each question in turn:
1. There is no single answer. It could be the ground is very compacted or thatch laden at 50mm depth and hollow coring may be helpful. Deeper compaction may require ‘spike and heave’ techniques, for example with a Verti-Drain, Terraspike or Soil Reliever. Shallower compaction might be best targeted with the Sisis Aer-Aid machine. To get the answer will require some site investigation by the greenkeeper and / or agronomist. Whatever problems are found, the right tool for the job will enhance establishment. Remember: choose your weapon! The good news is that the investigations may reveal that no treatments are required and, let’s face it, not deep spiking all your greens when it is not necessary will help avoid political flak caused by unduly disrupting playing surfaces, and allow a faster renovation.
2. Again, assessment is required of the area to be seeded. The outcome from treatments is to ensure that the seed comes into contact with the soil to enable it to germinate successfully. In most instances, sarrel rolling / micro-tining are good options. However, do not overlook the benefits of the impact of scarification, especially deep scarification (which in some circles is dubbed ‘linear aeration’) as this seems also to be especially good at aiding seedling establishment.
The aeration technique used at overseeding should try to enhance the uniformity of results from seeding activity as a primary objective rather than be used to overcome some underlying issue. This is the downfall of hollow tine aeration being used in renovations as seed establishes and ‘tufts’ out of the holes to give surfaces a speckled, measles-type appearance, which contributes to bobbly putting surfaces on greens.
Also to be considered is the type of seed mix being used. Some species such as perennial ryegrass and tall fescue will push their way up from 12mm or more, but others, usually those with smaller seeds such as bent grasses, smooth stalked meadow grass and so on, cannot tolerate deep burial. For these small seed species, intensive verticutting / scarification may be the best approach.
Very thatchy or poorly draining surfaces throw up a number of problems for grass seed germination and establishment. Thatch and seed make poor bedfellows and overcoming the presence of thatch is normally required before good seeding results are obtained. If poor conditions exist it may be better to concentrate on overcoming difficulties with thatch, poor drainage, shade and so on, rather than waste money on expensive seed that will fail.
3. This will be determined by the techniques selected in question one above. On fine playing surfaces such as greens, such treatments will normally be part of a renovation process therefore following topdressing works will minimise surface disruption and cover the loss of uniformity that comes with most aeration treatments.
As I mentioned above, hollow tining is especially prone to creating speckled greens if followed with overseeding and it may be preferable to carry out an initial topdressing after treatment and follow on with a pre-seeding aeration treatment a week or so later before applying a second topdressing to help dust in the seed.
4. This sounds such a silly question for some greenkeepers where budgets remain high enough that changes to a topdressing regime is not really an issue. However, currently there will be many clubs (including some in the historically prosperous south east region) where budgets are under pressure and cutbacks will be demanded. If there may be restrictions on follow-up work, the answers to the first question may be affected – after all there is no point in carrying out hollow tining to ‘soil replace’ a green when there are restrictions on a topdressing budget and / or hiring in a hollow tiner in the first place.
The choice of seed will depend on:
• The type of surface being seeded
• The environment at the course
• Timing of operations
• Particular difficulties encountered at the course / location, such as shade, waterlogging, disease, colouration and so on
• Soil type and maintenance inputs
• Any management / agronomic objectives regarding species’ populations.
There is no point in discussing specific seed mixes in a magazine article as these should be developed from site-specific needs. However, acknowledging general principles is worthwhile. I never fail to be astounded at how little thought is put into overseeding or primary seeding of a new site, particularly in areas such as species’ choices in the seed mix(es), sowing rates and depths, and cultivar choice … it’s almost as if the grass and the seed are two distinct and unrelated things!
In areas such as walkways and heavy traffic routes, the main species are likely to be based around wear-tolerant species such as perennial ryegrass, perhaps with proportions of smooth stalked meadow grass, sheep’s and strong creeping red fescues and so on, if there is a reasonable chance of them establishing.
On fairways it is usual to avoid ryegrass where possible and use traditional low-input species of fescue and bent grasses that demand less nutrient input and have greater drought tolerance.
On tees, overseeding is usually most successful with ryegrasses (plus perhaps some smooth stalked meadow grass), chewings and slender creeping red fescues and brown top bent.
On greens, overseeding choices are varied depending on the type of course you have. Creeping bent greens will, of course, be oversown with creeping bent. Poa annua dominated greens may not be oversown at all – although there are longer term downsides to this. Most club courses will overseed with a mix of bent grasses and fescue (chewings and slender creeping red) or just bent grass.
Reputable seed companies spend about 15 years or so bringing each new cultivar to the market. This represents a huge investment in our industry and although not all new cultivars perform better than their old predecessors, the overall trend is for better performance. When greenkeepers come to buy seed it is price, more now than ever, that seems to be the driving force in the purchasing decision-making process. This is false economy usually – if you are buying seed, look at the performance of the grasses in the seed mix before you look at the price. Remember it is your raw material and quality that counts! It may be your job to explain to the greens’ committee why cutting budgets is a false economy. Cheap seed is usually seed no one wants, it usually represents poor quality cultivars or old stock seed that has reduced viability and as a norm is best avoided. Never buy seed unless you have information on the cultivar content and valid certification.
Overseeding forms an essential element of the maintenance on any intensively used turf surface and failure to constantly re-introduce the desirable grasses in the form of seed to compete against the ingress of other less desirable species is asking for sub-optimal playing surfaces. Introducing new cultivars of species into the sward should enhance the resistance to disease and recovery response under wear pressures, and increase aesthetics and even green speed in the longer term.
Overseeding needs to be undertaken following suitable mechanical treatments to prepare the soil environment to make both the germination and subsequent establishment of the grass as successful as possible. Failure to prepare the ground properly will waste the seed to the point it might as well never have been bought in the first place. However, well prepared ground that allows good establishment of seedlings can only benefit in the medium to longer term.
Noel Mackenzie is the principal consultant at Sports Turf Consulting