Post category: Feeding
The removal of the mown grass from a lawn gradually reduces soil fertility because the nutrients in the removed grass are not recycled. Plant nutrients are also removed by rainfall. Feeding is necessary to replace lost nutrients, to encourage healthy grass growth and to allow the grass to compete with weeds and moss.
Feeding is essential
The first spring feed of the year is the most important because the grass will be hungry and weak after winter. Apply fertiliser in March or April to set it up for the growing season. Use a spring lawn feed, which is specially formulated for lawn grasses.
These fertilisers contain the nutrient nitrogen that the grass badly needs but, also, phosphorus and potash for balanced growth. General fertilisers such as 10:10:20 or 7:6:17 are not really suitable for a lawn, because they do not contain enough nitrogen. But they may be used, especially on light soils that are low in nutrients.
Use fertilisers at the rate recommended on the pack. Do not use more fertiliser than advised, or apply it when the grass is already growing strongly, as it only increases mowing. Apply fertilisers evenly to moist soil when rain is expected, or water them in on small areas. Scorching of the grass can be caused by uneven application, particularly in dry conditions.
Feeding can be repeated at least twice, at two-month intervals, using the specially formulated lawn fertilizers. Sulphate of ammonia (containing nitrogen only) and other agricultural high-nitrogen fertilizers, such as urea and CAN, can also be used if large areas are involved, because they are cheaper.
But there is a greater danger of scorching the grass through over-use of these because these are more concentrated, quick-release fertilizers and they can cause a very sudden burst of vigorous growth, and a lot of mowing!
There are also slow-release fertilisers which release the nutrients slowly over a period of months and this avoids the rush of growth after feeding with the normal fertilisers. These are more expensive than farm fertilisers but less effort in mowing.
Lawns can be fed in autumn as well to supply phosphorus and potash to toughen the grass before winter. Autumn lawn feeds should be applied in September or October.
Sulphate of iron can be used in autumn and winter to toughen grass, give it a good green colour and to reduce mowing the following spring. Apply 300 grams per 100 square metres every 6 to 8 weeks from the end of August to April. Spray it on, diluted in 5 litres of water, or apply it dry mixed with about 20 parts sand. This will control lawn moss too.
Wild flower lawn
In September/October, or March/April, a very good quality lawn should get a top-dressing of fine soil mixed 50:50 with peat. One bucketful per 4 square metres will give the grass new rooting material, and boost growth. It is quite a deal of effort to mix and spread a top-dressing, but very effective. A very good lawn should get this each year, but top-dressing can also be used once-off to boost a thin lawn, especially on poor soil. Some fertiliser and seed can be added to the mixture in the latter case.