Feeding a Lawn in Spring

We all know that lawns stop growing in winter. However, growth only stops on the surface. Down below, the grass is making a brand new root system. This process begins in the autumn as the darker nights approach and continues through till late spring, with perhaps a break during the depths of winter. In late spring, root growth stops and leaf growth takes over.

This is illustrated very well by this Minnesota Sustainable Urban Landscape Information Series publication which, lower page, shows the growth pattern of Cool Season grasses, the types we use in the UK.

As you will see, the Seasonal Plant Growth is still favouring root growth at this time of year. Grass does not really start growing in earnest until mid April, depending upon the weather.

Many people are in the garden centres right now buying high nitrogen feeds which stimulate leaf growth. The problem is that, if we do this too early, the roots stop growing prematurely. So when the dry weather comes, the grass has insufficient root to provide moisture, and consequently turns brown.

As I said in my article on moss, we want to build up the grass to replace the moss. And, consistent with our theme, the best way to do this is to develop the roots; then we can later concentrate on leaf growth.

How do we do grow roots?

We apply an autumn feed at the recommended rate. These might still be available in garden centres. They are often sold off cheaply at this time of year.

However, we need to be careful here since most autumn feeds contain ferrous sulphate to kill moss. If you have a moss problem and are willing to tolerate it turning black, then there is no problem. But can I make a suggestion?

Feeds can be supplied in either granular or liquid form. Since there is no time to waste, it would be best to use liquid since this will get into the plant quicker, through the leaves and down to the roots. Granules can be used, but apart from the fact that they are usually mixed with moss killer, they take about 2 weeks to start working and might need watering in if there is a dry spell.

If you cannot get a liquid autumn feed without moss killer, I recommend Phostrogen All Purpose Plant Food, the one in the orange box. It is not sold as a lawn feed (that's the one in the green box which we may be using later), but is high in water-soluble phosphate to nourish the roots.

APPLY AS LIQUID
Mix 20mls per 2 gallons in a watering can and apply this over 4 square metres. Continue every 2 weeks until you see improvement.

This is a good way to apply feed evenly without scorching. The trick is to get a coarsish rose. Mine lets me spread the can over about 20 sq metres very quickly.

This is rather a lot of work, especially on a large lawn. What I do is wait for rain to be forecast then apply at 100 mls per 2 galls per 20 square metres. Or you could use a Phostrogen feeder on the end of a hosepipe; or attach an applicator to your sprinkler.

APPLY AS SOLID
These new hand-held spinners are really good for granular lawn feeds. I tried mine last year and was very impressed. Only problem is that it is difficult to control edges, so could not use with weedkiller or moss killer since this would trespass on borders. It should work with dry Phostrogen. Apply at 5 mls per square metre every 2 weeks. Best put on dry grass when rain is due.



If your lawn is not too bad, or you have already applied an autumn feed, then wait another month when we shall be giving high nitrogen feed.