Carl White, Botanical Garden

Lime should be applied to established lawns every two years (in late May) to keep the soil pH in a favourable range for grass growth. If the soil is too acidic the grass plants can't assimilate nutrients very well and much of applied fertilizer is wasted. Lawns prone to becoming mossy should be limed every year.

Thatch is a layer of dead stems, roots and grass blades mixed with the living plants on the surface of the soil. About one-alf inch or so of thatch is fine as it provides a cushion for falling children/foot traffic and can help insulate the lawn against extreme cold and heat. When the thatch layer becomes thicker than an inch it can cause problems (shallow roots, drought susceptibility) and should be removed. There are gadgets and mower attachments for this but on the average size lawn a gravel rake works just fine.

Mowing is more important than people may realize: too short and the grass roots can burn during hot, sunny weather; too long and the turf doesn't thicken up as it should. For most turfgrasses 2 to 2 1/2 inches is about right with a mowing interval of 10 to 14 days. Keep your mower blade sharp so it makes a clean cut, not a ragged tear. There is no need to remove the clippings; just blow them in the same direction and keep running over them on the next pass. By the time you finish you will have mulched your lawn as well as cut it. The clippings are high in nitrogen and since they are the youngest and freshest part of the plant they decompose quickly and you will save on fertilizer.

Fertilizer should be applied one to three times a year depending on the type used and what you want from your lawn. A general rule of thumb is that the cheaper the lawn fertilizer the more water soluble it is and more often it will need to be applied. Slow release lawn food is better and one application can give 10-12 weeks of constant feeding (the best part of our growing season). Grass fertilizer is high in nitrogen so look for a high first number on the bag. A ratio of 2:1:1 (14:7:7) is good for early season and 1:1:1 ( 7:7:7) for late season applications.

The best weed control is a good, thick, healthy lawn. The healthy, dense grass will exclude light to the soil level and weeds will not readily develop. Those that do establish themselves can be dug out (try and get the whole root) with a weeding tool or a long shafted screwdriver. Many lawn herbicides are available for the chemically inclined but I never use them and my lawn looks fine to me. Insect control is another matter and if you have chinch bug you will have to ‘spray and pray'. Visit a local garden centre for advice on this.

Watering (if needed at all) is best done in the early morning when evaporation losses are minimal. One good, deep watering is better then several light ones as it encourages the roots to go down in search of the moisture, not hang around the surface where they can be more affected by drought and temperature extremes.

Important: Apply lime and fertilizer when the grass blades are dry (so it doesn't stick to them) and when rain is in the forecast to wash it into the soil. Remember you are not treating the grass but the soil under it. When applying anything (lime, fertilizer, pesticides) read and follow the manufacture's rates and safety procedures that are on the bag. These rates are the results of extensive research and to achieve the desired result should be followed closely.

The Memorial University Botanical Garden is open May - November, seven days a week, from 10 a.m. to 5 p.m. Come on up and visit your Botanical Garden.