Visitors tour the container area of the GTI Annual Trial Gardens.

On the Lawn

July has been cool with relatively good rainfall up to this point so lawns in most parts of Ontario are still actively growing and green. There are a few areas that have been a little drier so these conditions may not apply to your lawn. The longer range forecast is calling for warmer and drier conditions. Up to this point, lawn irrigation in southern Ontario has not been a significant issue but if it does turn hot and dry, this may change.

Kentucky bluegrass, the most common lawn species, has excellent drought tolerance. This doesn't mean it stays green through periods of drought but that it has the ability to go dormant during dry periods and will green up quickly once the rains return. There has been a lot of interest in fine fescue blends which have been agressively marketted as low maintenance "ecological lawn" mixes.  They require less moisture than Kentucky bluegrass and can thin out under wet conditions, but their drought avoidance mechanism is not as good as Kentucky bluegrass and they do require some supplemental irrigation through extended periods of hot, dry weather.

We have received a lot of questions this year about weed control in lawns. Check out our page on weed management for more details about how to control weeds in your lawn under the new Cosmetic Pesticide ban. There also seems to be a lot of confusion about what you can and cannot do under the new ban. The chemical herbicide Round-up (active ingredient glyphosate) is still available on store shelves. It can only be legally used for control of weeds that are poisonous to the touch (poison ivy, poison parsnip, etc.). If you are looking for something to non-selectively remove weeds from cracks in paving stones or an area you are renovating, your only product options are horticultural vinegar or fatty acid. It has been suggested that acetic acid can be used as a spot spray to remove weeds from lawns but proceed with care as it will knock back the surrounding grass as well and you will end up with brown spots all over your lawn. Treatment is best applied when weeds are actively growing.

A more challenging lawn weed control situation is the removal of creeping charlie, bindweed and other creeping weeds from lawns. These weeds don't stand out as individual plants and become intertwined with the grass plants making physical removal or spot spraying with acetic acid virtually impossible. The bad news is that there is really no option to selectively remove these weeds from the lawn. A number of new biologically based herbicides are making their way to the market and may provide some options in the future. At the moment, your best bet would be to insure that your fertility, irrigation and mowing practices are optimized to give the grass a fighting chance in the competition with these weeds. A lawn can still look like a lawn even with a high content of these and other weeds.

 

Acceptable looking mown lawn from a normal viewing distance.

 

Up close the creeping charlie content is more evident.

 

Clover is also flowering now and providing a nectar source for foraging bees. Clover is not a completely unwelcome visitor to the lawn as it provides some colour during periods of drought as it stays green longer than grass as the soils dries out. Clover also has the ability to fix nitrogen from the atmosphere and convert it to a form that grass plants can use which is why it is often found in ultra low maintenance roadside seed mixes. You can even overseed clover into your lawn if you are converting to a lower maintenance lawn. Be sure to use dwarf Dutch white clover. Spring is the best time to overseed with clover, preferably immediately after core aerating to provide some germination sites. The next best time would be late summer.

 

Chinch Bug Management

There have been some reports of chinch bug infestation on lawns this summer. Under the cosmetic pesticide ban, there is no legally registered product for their control. Turfgrass cultivars with a high level of endophytic fungi may have some resistance. If you are overseeding or establishing a lawn, consider this when selecting the appropriate species and cultivar. Of the grasses used in Ontario, some fescues and perennial ryegrasses have endophytic fungi content.

Irrigated lawns are also more resistant to chinch bug damage. Monitoring for the insects and perhaps irrigating only the infested area of the lawn if you live in an area subject to watering restrictions may be a management option. For more information on this insect, including how to identify damage and monitor insect populations, consult this OMAFRA on-line factsheet.

 

Giant Hogweed Alert

Although not a weed found in lawns, giant hogweed is an invasive weed that is becoming more prevalent in Ontario particularly in wetter areas. It grows very tall with flowerheads reaching to 3 meters. Contact with the plant can cause a very severe rash in some individuals so approach with caution. This weed qualifies for control with chemical herbicides and eradication of plants prior to flowering is recommended to help prevent further spread. Consult this page for information on identification of giant hogweed.

 

In Praise of Unmown Turf

Outside of ornamental grasses, the more common turfgrasses are under appreciated for their form and natural beauty. A large section of my backyard is left in an unmown state for most of the season. Weeds are limited in the area although thistle is creeping in a back corner and will have to be physically removed. I leave some plants like mullein which is a wild plant that I find interesting as well. I am also experimenting with giant Scots thistle which needs to be managed carefully but is a very imposing plant in the landscape easily growing to two meters in height.

As you can see from the images below, my backyard has a recreational purpose which is somewhat enhanced by the unmown areas. However, even if you do not have a golf green in your backyard you can utilize unmown areas to define space and add interest to your landscape. Mown pathways can lead to other areas of the yard or garden. It reduces lawn mower use as well as the time your spend on lawn maintenance.

Unmown turf compliments more intensely managed areas.

Clump of naturally occuring tall fescue clump surrounding ornamental grass (zebragrass - Miscanthus sinesis 'Zebrinus').

Naturally occurring mullein stand sentry.

 

Unmown does not mean unmaintained. A single late fall application of fertilizer should suffice and you can even experiment with no fertility as the areas mature. Experiment also with transplanting desirable wildflowers or other plants into the area to provide additional visual interest as well as to attract more birds and butterflies. Cutting back unmown areas once a year, usually in the fall, is recommended to prevent them from becoming too matted with dead organic material. A string trimmer can be used although I like to practice my scything skills each fall. In smaller areas on city lots, a pair of hand shears may suffice or you can even try running your mower through the area set at the highest setting and proceeding slowly. I also mow the areas after removing most of the material to further discourage rodents from overwintering in these areas. The down side of unmown turf is that it does provide cover for rodents and other wildlife. I haven't seen any coyotes in my backyard as of yet but there are some rabbits taking advantage of the vegetative cover. Unmown grass is not for everyone but it is an option to consider if you are looking for a lower maintenance approach to parts of your property. In the interest of neighbourhood relations, you may want to discuss it with your neighbours as well.

If you have any questions or topic you would like covered in future issues of the GTI Lawn & Garden Letter, please email them to me. Enjoy your lawn and garden.