TGA Quality Standards for Cultivated Turf

These standards apply only to cultivated turf produced by members of the Turfgrass Growers Association (TGA) and supplied with a declaration that it meets set criteria. The intention is to set a minimum standard for good quality cultivated turf for use in general landscape situations. Turf intended for some uses on sports facilities demands a more rigorous standard, particularly in relation to soil type, which this standard does not address. Turf consisting predominantly of agricultural or wild grasses cannot by definition meet the TGA quality standard.


The results of the following assessments, together with a statement that the turf has been grown from good quality turfgrass cultivars on a suitable soil type are to be recorded on a declaration form completed by the turf grower or his agent on the day of lifting and made available to customers.


Properties of turf meeting the TGA Standards


The dimensions of the turves in the consignment are to be declared. The most common type of cultivated turf in the UK is the roll, 1 square metre or 1 square yard in area, and those parts of the standard relating to strength refer to this material. ‘Big rolls’ in a variety of dimensions (most commonly 25 square yards in area) are increasingly popular for large scale landscape projects. Turf may also be supplied in rectangular pieces of other sizes to be agreed with the customer in advance.



General health of the turf

The sward must be visibly free of commercially and economically controllable pests and diseases.

The Association is working with the wider industry to bring new control methods to the market in line with current legislation.





Cultivars of turfgrasses used for cultivated turf production should be shown in the edition of ‘Turfgrass Seed’[1] current in the year of sowing the crop and listed in the declaration. The turf is to be composed of the sown turfgrasses which should occupy at least 95% of each turf. Any other species present and their approximate % cover are also to be listed in the declaration.

The content of plants in the turf (grasses and broad-leaved weeds) is to be objectively assessed with the appropriate quadrats using the techniques described in ‘Methods’.

In the first instance a rectangular quadrat, such as the standard TGA 75 cm. square quadrat may be used, but in the event of a dispute or for a more accurate ground cover assessment the more precise “New optical point quadrat”[2] should be used. This is a more accurate instrument for the assessment of ground cover in close mown turf and the results of an assessment conducted as described in the ‘Methods’ (section B.1.b) will be final.

[1] Obtainable from The Sports Turf Research Institute, Bingley, West Yorkshire, BD16 1AU.

[2] Laycock and Canaway (1980). J. Sports Turf Research Institute 56, 91-92.



Cutting height

The height of the sward when harvested should not exceed 35 mm as measured using the technique described in the ‘Methods’ (section. B. 2. i)



Thatch or fibre thickness

The thickness of uncompressed thatch should not exceed 10 mm as measured using the technique described in the ‘Methods’ (section B. 2. ii. a and b).



Thickness of soil

The soil layer beneath the thatch should be between 5 and 15 mm deep as measured using the technique described in the ‘Methods’ (section B. 2. iii) and this thickness should be uniform within a consignment of turf.




A declaration must be made as to whether sod netting is incorporated in the turf. If it is present at point of sale it should be embedded in the turf and must not project above the thatch layer. (This statement does not apply to removable netting wrapped around pallets or “big rolls” to protect the harvested turf.)




To demonstrate strength, it should be possible to lift 1 sq. metre or 1 sq. yard turves clear of the ground by their shortest side. At least 15 out of 20 turves tested in this way should remain intact.




Rolls of 1 square yard or 1 square metre in area must weigh less than 20 kg. unless the turf is very wet due to rain on the day of harvest.



Delivery and Laying

For delivery, turves should be packed to avoid drying-out in transit and should be rolled or laid flat (grass to soil). Turf should be delivered to the site within 24 hrs of lifting. In spring and summer this period should be reduced to ensure that turf is fresh and green on delivery. Care should be taken whilst transporting, to avoid deterioration due to bad stacking, covering or excessive temperature. Turves should be stacked on cleared ground and to a height of not more than 1.4m. Turf should be laid on the day of delivery.




  1. Large areas of turf – whole fields or parts of field

To enable the whole area to be sampled, the conventional ‘W’ pattern of sampling as used in soil sample collection should be used with no less than approximately 5 stops for sampling for each hectare of field area. Thus, for example, a 5 ha. field would be assessed in at least 25 separate locations. It is the responsibility of the assessor to ensure that the number of assessments gives a true representation of the turf.


Areas where different plant associations are obvious, such as in wet areas or headlands of fields, should be assessed separately from the rest of the field and the harvesting teams made aware of them so that the appropriate declaration can be supplied to customers.


To introduce an element of randomness into choice of the location of the sampling position when used to assess a field of turf, the quadrat should be allowed to fall onto the ground, rather than being carefully placed. With the quadrat laid on the turf the area of each species present should be assessed as described in section B. 1 below.

  1. Individual turves or consignments of harvested turf

The TGA 75 cm. quadrat should be placed on two turves laid side by side and the assessment performed as described below.


  1. Quadrats

Quadrats are used to estimate the area of turf occupied by bare ground and plant species in the turf. The number of quadrats used determines the accuracy of the final value for % ground cover which should add up to 100%.

a. Rectangular quadrat

The TGA 75 cm. quadrat contains 100 square subdivisions, each of which is equal to 1% of the total area of the quadrat. To estimate the area occupied by species which occupy more than the area of one subdivision square, the assessor should imagine the separate plants are placed into one part of the quadrat and count the total area they occupy. Species which are present but occupy less than one square should be noted by a ‘+’ on the recording sheet.

b. New optical point quadrant

This apparatus is more accurate than other types of point quadrat because of the effect on the results of the size of the points used. Ideally a point of zero diameter (such as an optical cross wire) should be used when studying plants with leaf blades as narrow as those of turfgrasses. Using a point with a relatively large area increases the number of “hits” and exaggerates the % cover of species present, depending on leaf width. The “New optical point quadrat” combines the convenience of a conventional point quadrat as used in agricultural and ecological research with the accuracy of cross wires.


Each frame consists of 10 pairs of points which are sighted down and the plant species immediately in line with the tips of the points is recorded as a “hit”. Ten frames thus involves 100 hits. To assess a consignment of turf ten frames should be used on each of 10 turves taken at random from the consignment and the result expressed as % ground cover for each species.


  1. Ruler

The ruler used to measure sward height should measure from zero and have a pointed end so that it can penetrate to the top of the thatch layer of the turf without resting on blades of grass.

2 i. Measuring sward height

The height of the sward to the nearest millimetre should be measured in twenty places in the field and the average height recorded on the declaration.

2 ii. Measuring thatch thickness

a. In the field

A triangular sample of turf of side approximately 10 cm. should be removed using a sharp knife and the perpendicular distance between the base of the crowns of the grass plants and the top of the soil layer measured after a period of at least one minute has elapsed to allow for any compression of the thatch caused by sampling to disappear. Twenty such measurements should be taken in the area to be harvested and the average recorded on the declaration.

b. In harvested turf

The thatch thickness as defined above should be measured on the cut edge of 10 turves chosen at random and the average shown on the declaration

2 iii Measuring soil thickness of harvested turf

 The distance between the underside of the turf and the base of the thatch layer should be measured on 10 turves chosen at random from the consignment and the average shown on the declaration.