Banishing weed invaders from your lawn

Weeds can be pesky invaders in your garden, but if you grow a healthy, full lawn, there'll be no place for weeds to get a hold. But here are specific tips to deal with the more persistent species, like grass weeds that are already in your yard.

Weeds pop up in even the best-kept grass. However, you can do a number of things to minimize their occurrence.

1. Lawn weeds are opportunists; they will sprout in any uncovered piece of soil, but cannot compete with a dense stand of grass. Growing a good lawn will do much to prevent their intrusion.
2. Mowing at the correct time to the correct height — so that you do not take off more than one-third of the leaf length — will help build a healthy lawn.
3. Fertilize in the fall as the grass resumes active growth. Summer fertilization feeds the weeds more than the grass.
4. Water during periods of drought, adding at least three centimetres (one inch) of water each time, so that it soaks down into the soil to encourage deep rooting.

The hardest to control are grass weeds, which are often not noticed until mature.

• Crabgrass germinates from seed each spring. One plant, overlooked, can shed thousands of seeds to grow the following year.
• It is easy to identify, but tough to pull by hand, so use a small fork.
• Bad infestations are best controlled by using corn gluten applied in early spring, about the time forsythias are in flower.
• It kills the weed seedlings as they germinate. However, it's active in the soil for several weeks, so do not overseed with desirable lawn grass seed after using it.

Weeds present in the lawn can tell a lot about the soil type and how to correct it.

• Ox-eyed daisy, foxtail grass, and yellow dock indicate a wet soil that needs to have the drainage improved.
• Mosses and wild strawberries thrive on acidic soils, indicating the need for lime.
• Plantain and knotweed will be found growing on soils that have become compacted and are in need of aerating.

Perennial broad-leaved weeds, such as dandelion and plantain, can be dug by hand. The aim is to grow a lawn that is deep-rooted so it can withstand drought, and one that has a dense texture, which will crowd out existing weeds and not allow seedlings to become established.

With a neglected lawn, it may be necessary initially to spend some time digging out the worst of the broad-leaved weeds.

• Plantain in particular spreads across the grass and leaves a big bare patch when it is removed.
• Dandelions dig out easiest in early spring before they grow feeder roots off the main taproot. They are less likely to break off at this time also.
• Weed control comes down to growing a good lawn by fertilizing at the right time, cutting to the best height for the time of year so that the grass blades shade out the weeds, and watering when required.

Moss is most likely to develop in shady places, particularly on underfed grass or where the soil has been compacted.

• To eliminate, add fertilizer, improve the surface drainage, and aerate the soil.
• Algae usually occur only where there is standing water.
• They can usually be eliminated by improving the drainage.