April 18, 2019
There will by now be some broad-leaved weeds present, many of these will be perennials or biennials that have overwintered, one of the most common early weed that is very visible especially under trees are celandines. These have a pretty flower but quickly disappear without much human intervention.
There are many selective weed killers available although most are only available to professionals. These are manly hormone acting and won’t work very effectively whilst we still have cold nights, so it is worth waiting a week or two until the nights begin to warm up.
With this high pressure, we have had very little rain so the soil is quite dry, where renovation works have been carried out, especially where we have included overseeding, water will be required to get the seed to germinate. There is moisture in the soil but in the top few millimetres where the seed is will be quite dry. Watering should be carried out at the latter part of the day and not too much, we just need to dampen the surface and then this will stay damp all night.
As the soil temperature start to rise, grass will start to grow and by now we will be cutting on a fairly regular basis. This means we should be applying spring nutrition. Nitrogen is the most important element as the plants try to put on significant leaf growth. We should also be applying potassium which is an important macro nutrient relating to root growth. Trace elements such as magnesium and manganese are also important at this time of year.
Scarifying can continue through April although we need to be careful with the dry conditions. We need to be gentle if water is not available, otherwise the lawn may well not recover. If there is a heavy layer of thatch, is really needs to be dealt with next autumn as it is unlikely that the lawn will recover if warm/dry weather appears in the near future.
With the dry weather, the soil has begun to dry nicely underneath and as we move towards the end of the month, it will be a good time to aerate. The idea of this activity is to form cracks in the soil which allow air and water movement and also give roots an opportunity to better access into the soil. If aerators are used in wet conditions, all that happened is the soil structure is damaged and the tines cause a smearing effect within the soil effectively sealing up the holes they create. This then means that water and air are not able to penetrate.
When mowing, the cut height can be reduced towards the end of the month but don’t cut below 25mm. Try to avoid cutting the grass is frosts are still forecast.