GTI Lawn & Garden Letter

Entertaining advice for home gardeners with a focus on lawn and garden care and the outdoor gardening lifestyle. Suitable primarily for people living in northeastern North America and similar temperate climates in other parts of the world.

Thursday, June 01, 2006

What's Happening in the Garden

If you are in Ontario, I hope the heavy rains and winds that followed the heat wave didn't wreck too much havoc in your garden. Time to stake the peonies although they probably should have been done a few weeks ago. I use steel rebar for poles, nicely rusted to blend into the garden, and brown jute twine. The fancy prefab wire supports look nice but are a bit of an investment.

One of my favourite plants is a type of peony that typically doesn't require staking, the tree peony. More of a small woody plant than a herbaceous perennial, the tree peony is slow growing and rarely reaches a meter in height. The flowers are significantly larger than herbaceous peonies reaching pie plate proportions. They are beautifully scented. The foliage is attractive and the large finger-like seedpods provide some additional interest into the summer and fall.

Tree peony blossoms

Another of my favorite spring plants is the old fashioned bleeding heart - Dicentra spectabilis. Very tough and hardy spring flowering plants that fade away in the summer. Good for planting around later flowering perennials. Shade tolerant and available in pure white (Alba) or pink flower colour (species). See if you can pull a flower apart and make a tea setting from the various bits and pieces.

White flowered bleeding heart.

Pink bleeding heart

'Lanai Purple Mosaic' Trailing Verbena

The feature plant from the GTI Annual Trial Gardens is 'Lanai Purple Mosaic' trailing verbena. A great container plant this new variety bred by Goldsmith Seed has excellent powdery mildew resistance and good bloom performance during the heat of summer.

On the Lawn

Crabgrass are beginning to germinate making it too late for the use of materials like corn gluten meal that prevent seed germination. If you are concerned about crabgrass development at this point, talk to a lawn care professional about what options may be available to you. increasing your mowing height and providing adequate nutrients to keep your lawn thick and healthy will help prevent crabgrass infestation.

Crabgrass seedlings on a bare spot in a lawn.

The larvae of the European Cranefly (called leatherjackets) and European Chafer (called white grubs) are approaching full size and damage should be tapering off as they move into their pupal stage. Hot spots of white grub damage may be treated after adult flight is observed a little later in the season. Parasitic nematodes can be applied in August or September or a material called Merit can be applied earlier in the season to control the grubs while they are still small. it can only be applied by a licenced lawn care professional. There are no registered controls for leatherjackets in home lawns.


A great way to start a lawn or repair your damaged lawn, particularly at this time of year, is to use nursery grown sod. Ontario has some of the best sod producers in the world and a competitive market that keeps sod prices low. If you are interested in how sod is harvested in the 21st century, check out this machine.

You may question whether sod harvesting removes too much soil from agricultural fields. A study conducted several years ago showed that sod production is one of the most soil conserving crops you can produce. Grass is a great groundcover that prevents erosion from the fields through most of the production cycle. Grass also catches soil that may blow in from adjacent areas. When sod is harvested, it leaves behind a significant amount of root material that adds organic matter to the soil. Also, if you look closely, you will see that there is actually very little soil on a roll of sod. It is mostly grass crowns and leaves with a thin layer of soils and roots.

Sod needs to be kept well watered until it begins to root into the underlying soil. It provides a quick cover that suppresses weed development. Lawns seeded at this time of year will tend to have very high weed populations. Seeding is best left to the late summer/early fall. That's when most sod farms reseed.

Sod cross section.


I had a few questions about my recommended perennial ryegrass overseeding rate of 10 pounds per 1,000 square feet which is above the normal recommended rate of 3-5 lbs. per 1,000. There is some evidence, which we are currently studying in more depth, that high overseeding rates of perennial ryegrass will actually help to suppress weeds in a lawn or sports field. I would encourage you to experiment with different rates on your lawn to see what works best in your situation.

Lawns and gardens are complex communities of various organisms with many variables. A single cookie cutter approach rarely works for everyone. Try different things, keep written records rather than rely on memory and most importantly, enjoy your lawn and garden. It should be a place of recreation and relaxation.

I'm going to polish up my bocce balls for the weekend...