Clover is a major headache for many lawn owners. During the dry days of midsummer the bright green patches stand out against the dull and pale grass. This patchy effect is an eyesore, and control was difficult until the discovery of the newer-type selective weedkillers.
The clovers you are most likely to see are white clover (Trifolium repens) and the smaller yellow-flowering species known as lesser trefoil. As with all clovers, they are encouraged by both water shortage and nitrogen shortage. So wherever clover is a problem you should feed with a nitrogen-rich fertilizer every spring – never use a phosphate- or potash-rich fertilizer at the start of the season.
White clover control
If clover has become well-established use a combination of techniques. Rake regularly before mowing so that the creeping stems are brought up to meet the blades. Also water the lawn during drought, or clover will spread rapidly! In addition a chemical attack is needed. Lawn Sand is a useful treatment in spring – top growth is burnt off and vital nitrogen for clover control is provided. Apply a selective weedkiller which contains two or more ingredients in June or July – repeat the treatment six weeks later.
Black medic and lesser trefoil control
Black medic (Medicago lupina) and lesser trefoil are less sensitive to selective weedkillers – a repeat treatment after about six weeks will be necessary. These weeds are an annual, so hand weeding of small clumps is practical. Use a grass box when mowing.