March is a good time to make your first lawn fertilizer application unless you applied fertilizer last September or October. If so you can probably wait until late May for your first application. The carryover effect of fall fertilizer application is enough to give grass a good start
If you did not make a fall application of lawn fertilizer, you have several choices. If you have a lot of dandelions and other broad leaf weeds, a weed and feed combination fertilizer and weed killer is a good choice. You accomplish two jobs with one application. The difference in price between regular lawn fertilizer and weed and feed is usually only a couple of dollars. Grass should be wet when weed and feed is applied so that it sticks to the weed leaves. The weed killer is absorbed through the leaves and carried down to kill weed roots.
Another choice if you have few or no weeds is to apply Natural Guard Soil Activator. The active ingredient in this product is humic acid, or sometimes referred to as humates. It is a naturally occurring mineral which stimulates earthworm and micro-organism activity. They quickly decompose the thatch (dead, brown leaves and stems). This process releases nitrogen, which stimulates grass growth.
Another choice if you have few or no weeds is to apply a regular lawn fertilizer. There are many brands and formulations of lawn fertilizer. I prefer a balance of 3-1-2 nitrogen-phosphate-potassium. An organic fertilizer might have a 6-2-4 analysis. Most chemical lawn fertilizers have at least 15 per cent nitrogen, giving a 15-5-10 analysis. Many lawn fertilizers contain a higher percentage of nitrogen and smaller percentages of phosphate and potassium. They are also satisfactory. These numbers are prominently displayed on the bag. If you look at the guaranteed analysis label, you can see exact percentages and sources of each nutrient element.
Organic fertilizers are naturally long lasting. Chemical fertilizers often have a combination of quick acting and slow release nitrogen. Methylene urea is a common slow release nitrogen compound. Sulfur coated and poly coated nitrogen is also slow release. Sometimes granules are coated with both sulfur and poly. If slow release nitrogen is included in the fertilizer it will usually indicate what percentage on the analysis label.
Iron is another important nutrient element for lawns. Very small percentages of iron (often only one or two per cent) are adequate. Iron also controls moss. Iron content of at least 4 percent is necessary for moss control. Organic fertilizers naturally contain iron and other micro-nutrients, but not enough for moss control. Moss control or “moss out” can be purchased separately or in combination with a lawn fertilizer.
If you make your first application of fertilizer before April first, a second spring application which contains slow release nitrogen (organic or chemical) should be applied in May or June (normally about 2 months between applications).