Gardening with Allen: Now is a good time to feed lawn

My lawn has started to grow again but it is not as green as I would like. Is now a good time to fertilize and make it greener? Is this a good time to fertilize trees and shrubs? Can I control moss at the same time?

Lawns start their strongest period of growth in the early spring. Fertilizing now will not only turn the lawn a darker green but will also develop a strong root system for strength during our summer dry season. This is also a time when lawns grow thicker with new tillers.

Iron is an important ingredient in lawn fertilizer because it is causes the extra dark-green color that you are looking for. It is also desirable to have some of the nitrogen in slow-release form for the spring application. Use a lawn fertilizer with at least 25 percent slow-release nitrogen because it lasts much longer. Check the label to see if it contains water-insoluble nitrogen. The most common way to make nitrogen insoluble is to coat the pellets of urea nitrogen with sulfur or poly. This coating allows the water to flow through and dissolve a little nitrogen every time it rains or is irrigated.

I generally feed my trees and shrubs with lawn fertilizer or 16-16-16 at the same time I make my spring lawn application. Trees growing in the lawn are fed at the same time you fertilize the lawn.

I use a 16-16-16 fertilizer for flowers and vegetables. Perennial flowers get their first feeding in the early spring just as they are beginning to grow. I fertilize perennial vegetables like asparagus, rhubarb and garlic in March also. Other vegetables and flowers are fertilized at the same time they are planted. I often use a slow-release encapsulated fertilizer like Osmocote for container plants.

Moss growth is something that comes with the Northwest climate. The wet conditions and acid soil are ideal for moss growth, especially in shady areas.

Moss-control products for plants contain an iron compound that actually kills the moss. It turns moss black within a few days. Then it gradually dries up and becomes part of the soil. Some lawn fertilizers contain enough iron to kill the moss. The fertilizer will be clearly labeled for moss control. The strongest and cheapest moss-control product is pure ferrous sulfate. It is available from landscape supply stores such as Site One and Horizon Landscape Supply.

Lime is also effective in discouraging moss growth because it makes the soil less acid. However it takes iron to give the quick kill. It is a good idea to apply lime to lawns and other plants once a year. However, lime should not be applied to rhododendrons, azaleas, blueberries and other acid-loving plants.

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