Getting to the Root
of a Healthy Garden
May 5, 2004
Overwatered plants are much less likely
to survive a drought, says Arboretum gardener
Lenore Ross of the Arboretum spends her days caring for thousands of plants, including these in the greenhouse behind the Hilton Centre.
Photo by Martin Schwalbe
Sprinklers and watering cans seem to be as synonymous with gardening as pruners and trowels, but a watering hose can rarely be found in the hands of arguably one of Guelph's busiest and most prolific gardeners.
Lenore Ross, the Arboretum's gardener, is working in high gear on the facility's gardens and on germinating all the seeds for the Arboretum Auxiliary's annual plant sale in September. Although her days are spent caring for thousands of plants, she spends little time watering them once they leave the greenhouse and shade complexes behind the R.J. Hilton Centre on College Avenue.
In fact, apart from hoses in three specialty gardens, there is no irrigation system in the Arboretum.
“All of the gardens get watered when they're first installed, but that's about it,” says Ross. “Sometimes during a long, hot dry spell in August, we'll water new plantings with a water wagon attached to a tractor, but it's infrequent.”
The large number of hardy drought-tolerant plants in the Arboretum is one reason an irrigation system isn't necessary, but Ross says that in general, people overestimate how much water plants and lawns actually need.
“People overwater their gardens far more often than they under-water them,” she says.
City water restriction guidelines and the desire to conserve our natural resources and avoid high water bills aren't the only reasons people should cut down on their watering habits. Overwatered plants are much less likely to survive a drought, says Ross. Plants need oxygen as well as water, so if you give them too much water and the soil is saturated, the roots have to come up higher to get more oxygen.
“In the event that you stop watering, you have roots very close to the surface and they're going to dry out faster. If you're watering less frequently, those roots are going to be deeper, still have the oxygen and be able to withstand the drought when you stop watering.”
Watering infrequently and deeply is the key to healthy plants, says Ross. It's also best to water in the morning to give the plants' foliage the entire day to dry off.
“If you water in the evenings, the foliage is wet all night long, and there's a greater chance of diseases developing.”
Putting plants with the same water needs together also helps cut back on water use because plants can have a greater mass of soil that's damper, says Ross. And creating shady areas in the yard cuts down on the intensity of the sun and helps create a microclimate of more humid air.
She notes that when moisture is scarce and temperatures climb above 30 C, most of the lawn grasses in Ontario go dormant. Watering helps a little, but a better, longer-term solution is to add a mixture of clover and other more drought-tolerant grasses throughout the lawn, she says.
Ross holds two U of G degrees — a B.Sc.(Agr.) majoring in resources management and an M.Sc. in rural planning — but she accumulated her immense knowledge of horticulture from experimenting with gardening on a large property she and her partner owned in northern Ontario.
“Like many people, I started gardening because I had two young children and wanted to spend time with them outside.”
She started out with only a few plants, but the number kept growing. People soon began admiring her gardens and asking her for advice on their own landscape designs. She opened a landscape planning business called Gardens by Design that she still runs today.
Ross and her family moved back to Guelph in 1998, and she began working at the Arboretum in 2001. She maintains the Gosling Wildlife Gardens, the David G. Porter Memorial Japanese Garden, the Edna and Frank C. Miller English Garden, the Italian Garden, the OAC '56 Park in the Garden and many smaller ornamental garden areas throughout the Arboretum.
She's also one of the big muscles behind the Arboretum Auxiliary's plant sale. Ross spends one day a week helping the many auxiliary volunteers plant and transplant some of the more than 10,000 woody and herbaceous plants that will be offered for sale Sept. 11 from 9 a.m. to 3 p.m. at the Hilton Centre.
It's time well spent because last year's sale drew about 2,000 people from as far away as Ottawa and Windsor who bought $43,000 worth of plants in six hours. The funds generated enable the Arboretum to maintain the grounds and implement improvements and new developments.
Now in its ninth year, the sale has grown through word of mouth and through articles and mentions in Gardening Life and Canadian Gardening, as well as smaller gardening publications.
“The gates open at 9 a.m., but people are already lined up before I arrive at 7,” says Ross.
The sale includes many native plants that are known to be hardy in the Guelph area, but she also grows more obscure plants that appeal to collectors. “I know that if something is rare, it will sell.”
One of the rarer plants she's been growing for this year's sale is Acanthus or bear's breeches, a large plant that has a flower similar to that of a foxglove or snapdragon, but it's purple and grey in colour.
Ross gets the seeds from seed exchanges offered through partnerships with international botanical gardens and specialty societies the Arboretum belongs to. She says there is definitely a trend towards bold, bright colours and textures.
“I think as a generation of gardeners is maturing, they're also becoming more confident in their gardening abilities, so they tend to move away from the soft pink and purple flowers and have fun combining hotter colours like acid green with purple.”
In the dozens of talks Ross gives at the Arboretum and for horticulture clubs around Ontario, she finds that people often want to be reassured that they're doing the right things with their gardens.
“I think a lot of people have an innate ability to garden, but they don't feel confident to do what they know might be right. People think there are rules, but that's simply not true. I tell them to trust themselves and draw on their own experience.”
She also gets a lot of technical questions about diseases and insects. People should look at the whole of their garden when trying to assess their problems, she says.
The Arboretum offers a variety of workshops on plants throughout the year. Upcoming sessions include “Plant Propagation” June 8, “About Trees” June 22, “Fern Identification and Propagation” July 8 and “Growing Native Plants From Seeds” Sept. 21 and 23.
For more details, visit the website www.uoguelph.ca/arboretum.