Autumn feeding: high potassium, low nitrogen

Why a different feed in autumn

In spring the goal is leaf growth and color, so the feed is high in nitrogen. Going into winter the goal changes: strong roots and tough, hardy grass. Potassium (the K in NPK) strengthens cell walls and improves resistance to frost and disease. Nitrogen late in the season does the opposite, pushing soft new growth that frost damages and that is prone to disease such as snow mold.

When and how much

Apply between late September and the end of October, at 25–30 g/m² (about 5–6 lb per 1,000 sq ft) of an autumn lawn fertilizer that is high in potassium and low in nitrogen. Check your product's label rate.

How

• Set the spreader to its calibrated setting and make two passes at right angles.
• Water it in, unless rain is due within 24 hours.
• If you have just overseeded, give the new seed a starter fertilizer instead; save the autumn feed for established grass.

Do not skip it

An autumn feed is one of the cheapest ways to get a lawn that greens up early and evenly in spring. Pair it with scarifying and aeration for the most complete autumn renovation.