Winter Lawn Care

So winter, with its lower temperatures, is an ideal time to catch up with important lawn care. Which lawn care treatments will depend on whether you have a cool season or warm season grass.

Cool-season grasses continue to grow in cool weather even after their top-growth stops. This continued growth occurs in the root system. Developing a good root system will help the lawn to survive the heat and drought of the next summer. If there is a good root system, there will be good top-growth as well. An important function of grass roots is to store extra food in the form of carbohydrates that will be used later by the plant. These carbohydrate reserves are drawn on to produce the new growth that is experienced in the Spring. This reserve continues to supplement the plant through the heat of summer.

Scarifying is the process of raking the lawn to remove dead material. It is also a technique used for removing thatch. For warm season grasses this is best performed in the Spring, because the time taken for the lawn to recover will be less in the warmth of spring. Cool season grasses are generally scarified in the Autumn.

After scarifying or aerating a top dress of a mixture of sand and decayed vegetable matter (e.g. Peat, Compost etc)

Herbicide labels will  invariably indicate the times of the year to apply selective (post emergence) herbicide. But here in the Mediterranean, it is frequently possible to take advantage of the milder winters to apply selective weed killer. This can be a period when a lot of seasonal weeds appear.

The rules for application of the herbicide become more important for best results:

1) Do not apply too early in the day if there is dew.

2) Do not apply if it is windy.

3) Do not apply if there is rain forecast. (sprayed herbicides)

4) Do not apply to drought stressed weeds. Only apply if weeds are growing. Hint - water the lawn day before.

5) Do not apply if the temperature is below the min temperature specified on the label.

6) Only apply if there is going to be at least a few hours of clear weather before sunset.

7) Do not apply on a cloudy day. 

If you are interested in killing weed seeds (e.g. Oxalis), then apply the pre-emergent weed killer a few weeks before the first signs of the weeds.  

This is a great technique used in colder areas of the Mediterranean where the Warm season grasses change colour or turn shades of brown in the winter. Overseeding is done in the Autumn with a cool season grass which dies off when the heat of the summer arrives. If you overseed, make sure you choose an "Annual" type of grass and not a "Perennial" as you don't want any unwanted perennial grass competing with your summer lawn for water and nutrients.

If you have a cool season grass lawn, it will be doing just that - growing in the cool season. So it will need feeding. Actually after the stresses of the summer, the Autumn/Winter is the time that reserves are rebuilt.

Warm season grasses that do not hibernate during warm winters, can also benefit from a general purpose fertilizer to keep them looking green and healthy. Be careful not to apply Nitrogen based fertilizer in the winter as Nitrogen promotes new growth, which could be dangerous if a cold snap occurs.

The fertilizer label should contain three large numbers, which are the fertilizer analysis. The numbers represent the concentration per bag of the three macro-nutrients, Nitrogen - Phosphorus - Potassium, (N-P-K ). The analysis numbers are the percentage of nutrients by weight. High analysis numbers don't identify a fertilizer as a better product than one with lower numbers, it just indicates a higher concentration. 

There are many tools for aerating lawns, but a garden fork dug in to 3" or 4" will do the job, albeit a little more slowly.

Warm season grasses in mild winters will continue to grow. So they may need a little watering - maybe once a month or so. Cool season grasses, because of their shallow roots will also need watering, but more often, generally when the soil shows signs of drying out.