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Horticultural Database Introduction
Lawns are an almost essential part of British gardens, one that is greatly admired by visitors from warmer and drier parts of the world. Important for recreation, a lawn can also provide a foil to more colourful plantings, and a unifying theme to a garden. Many enquiries about problems of lawn care are dealt with by the Members' Advisory Service , and several have featured in the series RHS Help & Advice, in The Garden .
Drought
Lawns may begin to suffer after one week of dry weather. Raising the height of the mower will reduce drought stress slightly. Water lawns thoroughly to saturate the top 10 - 15cm (4 - 6in) of soil. Wetting only the top few centimetres will encourage surface rooting, making the lawn more drought-susceptible. Most water companies apply regulations to sprinklers. Scarify in autumn to remove thatch build-up. A thin thatch layer can act as a mulch, but a layer greater than 1cm can impede water penetration. Regular aeration is also important for moisture penetration to the root zone. Aerate in autumn, concentrating on worn areas.
Weeds
Most lawn weeds can be controlled by using suitable lawn weedkillers, but cultural measures may also be needed to improve the growth of the turf and reduce the likelihood of infestation.
Further information on lawn weeds is available in the Advice section click here .
Moss in a lawn
Mosses become established in lawns when grass vigour is reduced, under conditions of poor drainage, compaction, shade, excessively acid soil or close mowing. Treatment can be carried out at any time of year when weather is mild and the soil is moist, particularly during September and February or March. Moss killers are based on dichlorophen, cresylic acid or ferrous sulphate. They are contact in action with little or no residual effect, and moss will usually return if cultural measures are not implemented.
Cultural control
Hand-weeding is useful for removing a few scattered rosette-type weeds, such as daisy, dandelion and plantain. Raking will check the spread of creeping weeds such as speedwells ( Veronica species) , white clover ( Trifolium repens ), silverweed ( Potentilla anserina ) and sorrels ( Rumex species), if followed by mowing to remove the disturbed weed growth. Garden lime applied as a winter dressing can be use on acid soils as a deterrent against sorrels or field woodrush ( Luzula campestris ) that prefer fairly acid soil conditions. Avoid close mowing particularly where parsley piert ( Aphanes arvensis ) and mosses are present. Feed in late March or April to encourage vigour.
Chemical control
There is a range of weedkillers available for lawns. Fertilisers or mosskillers may be included in the formulation. They are ideally applied in spring or early summer, but can be applied at any time from April to August, when grass is growing strongly. Apply in cool conditions when there is little wind, to minimise the risk of damage to nearby plants by spray drift.
Speedwell
Do not apply weedkillers:
- in hot, sunny weather
- in windy conditions
- when the soil is dry or during drought
- during winter
- if rain is likely shortly after
- at higher concentrations than recommended by the manufacturer
Further reading
This is just one topic covered by the Society's monthly journal for members, The Garden , and recent articles of interest are listed below.
RHS Wisley staff. 1999, September. Problem Profiles: Red thread in lawns. The Garden (RHS) 124(9): 706-707.
RHS Wisley staff. 1999, February. Problem Profiles: Coarse grasses in lawns. The Garden (RHS) 124(2): 124-125.
RHS RHS Wisley staff. 1998, September. Problem Profiles: Repairing worn lawns. The Garden (RHS) 123(9): 672-673.
RHS Wisley staff. 1998, July. Problem Profiles: Dead patches in lawns. The Garden (RHS) 123(7): 526-527.
RHS Wisley staff. 1998, May. Problem Profiles: Speedwell in lawns. The Garden (RHS) 123(5): 374-5.
RHS Wisley staff. 1997, October. Problem Profiles: Lawn weeds. The Garden (RHS) 122(10): 750-751.
RHS Wisley staff. 1997, September. Problem Profiles: Thatch in lawns. The Garden (RHS) 122(9): 674-5.
RHS Wisley staff. 1996, September. Problem Profiles: Prunella in lawns. The Garden (RHS) 121(9): 588-589.
RHS Wisley staff. 1995, November. Problem Profiles: Worm casts on lawns. The Garden (RHS) 120(11): 720-721.
RHS Wisley staff. 1995, September. Problem Profiles: Moss on lawns. The Garden (RHS) 120(9): 580-581.
Links
Sports Turf Research Institute
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