The TGA Quality Standards for Cultivated Turf
These standards apply only to cultivated turf produced by members of the Turfgrass Growers Association (TGA) and can be 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 (610 mm x 1640 mm) or 1 square yard (16” x 81”) 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.
Deviation from the declared size shall be plus or minus 15 mm in width and plus or minus 5% in length.
General health of the turf
The sward must be green and must not be visibly affected by any pest or disease.
Suitable types of soil for turf production for landscape purposes are peats, sands (including organic sand) and loams containing less than 40% clay as determined by particle size analysis. Turf grown on soil designated as ‘clay’ is not suitable for general landscape purposes.
Cultivars of turfgrasses used for cultivated turf production should be shown in the edition of ‘Turfgrass Seed’ 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” 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.
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 turf 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 19 out of 20 turves should be able to be placed and unrolled without breaking.
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.