What obsessive gardener Marjorie Harris has learned from a lifetime of growing

As I head into old (old) age, I tend to think more of my garden's future and its future without me. Current plans are to let the trees and shrubs grow so damn big that no one will be able to remove them.

I once interviewed Amy Stewart, one of the greatest of all Canadian gardeners, who told me two incredibly important things: "You can't have everything," (I was too young to understand that at the time); and "My garden goes when I die."

She was right about both. In those days, I wanted every enticing plant I clapped my eyes on, never mind the provenance. I did learn to even things out, but it took time. And I know that when we move on or move out, the garden will disappear too. I do not despair, it has been a glorious 40 years of effort and much reward.

My ultimate plan is to make a notebook (if we sell the place) to help the new owners look after it. Should they intend to trash the garden, I will invite all my plant-loving friends to come by and dig up what they'd like. Why anyone would take a garden out is totally beyond me, but people are unpredictable and it will inevitably happen, despite the fact that my garden takes very little care to maintain and is, to my eye, one of the most beauteous places on Earth.

At this stage, I keep thinking there's no new news about gardening, but of course that's not true. Things are changing radically with weird fluctuations in weather affecting just about every spot on earth. Still, I will say what I've always said:

Plant natives — as many as you can.

Think of your garden as a hedgerow — make it both solace and habitat for birds and animals seeking sanctuary. Provide them with food (the right plants) and water (freshened regularly). Now you are stewards, and not just landlords.

Think sustainability. A term used much too casually, yet it is crucial that we gardeners pay attention. A garden with nothing but annuals is not sustainable, nor is a garden with only exotics. Sustainability is about balance between what nature needs and what we would like to see and do in our own garden spaces. The controlling hand should have a light touch.

Last year I had a water system installed, something I now recommend most people do. We need to manage water wisely, and use only enough to keep the plants going. I also mulch heavily at least once a year, usually in autumn, never scrape the leaves off the ground (just push them into the borders), and add compost regularly in small dabs around the plants if they're looking poorly. Larger amounts blanket the soil every two years to keep it healthy and thriving.

I prune endlessly. Well, not me, but my friend Monique (who has a great eye) hoovers her way through on an as-needed basis, and Derek Welsh (my favourite arbourist) comes in every once in a while to take out trees and fading giants I can't handle anymore. I pretty much leave it alone except for the occasional walk-through and pull out the odd annoying weed.  

So it's the same old/same old — use your brain, and the garden will tell you what to do. When plants look crappy it's because there's something wrong — too much water is as bad as too little water. A good hit of compost will help as much as an aspirin helps a headache — somewhat, but not entirely.

I have looked for and tried just about every formula going to improve plant health. Some are okay, but most just make you feel better, because you've done something. Unless the plants have sunk into a gloom-ridden miasma of powdery mildew or some other horror, they will chug along pretty much the way I do — slowly, and sometimes with help.

I'm also getting pretty cold-blooded about some plants. If they die, I will replace them once and then it's quits. Gone. Out. Time to try something that makes more sense. Years ago, I tried to grow Betula pendula 'Trosts's Dwarf', on three, maybe four occasions and it would croak every time. A divine plant to be sure, but not meant to be in my garden. Now I pay attention to things like that. Which is not to say that my sense of adventure is gone, but only that my sense of sanity is prevailing.  

In a few weeks I will be out in the nurseries along with the rest of you, buying beautiful choice things for clients and slipping the odd exquisite thing into my own basket. But I won't be going wild with excitement, and instead will use more caution, as I have no idea how hot/cold or wet/dry the coming seasons will be. I am also reluctant to take a chance on things — new hybrids or unfamiliar cultivars.

Last year, we watched plants fry in front of our eyes. Now, I'm asking a lot more questions, like "Should I be planting this at all?" "Is it appropriate for this particular ecosystem, or should I think long range, bigger stuff?" In extreme weather, the bigger the plant, the more likely it will be able to withstand some temporary aberration. In the past I have always advised in favour of smaller plants that will acclimatize on their own. Now? I dunno. Be guided by your budget, and your knowledge of the kind of space you have.

If you decide to get involved with the Front Garden Vegetable Movement, bear in mind how far car exhaust can travel, and how much of it there is. I wouldn't plant vegetables across from a school or a community centre, where everyone lets their vehicles idle for far too long.

If you do get on the native plant trend, find out what kind of natives work for your particular conditions. In some cases they can take over, become invasive and downright pernicious. I think of the lovely Trumpet Vine, Campsis radicans. It seeds, it spreads its roots underground and birds drop it all over the place. A plant I wouldn't go near in my area of Ontario. Yes, it attracts hummingbirds, but so do a lot of other plants with deep tube-like blooms. It's the Year of Making Better Choices.

It pays to do a bit of research, and there is a lot of good information out there. Ask around. Check on your neighbours and see what they are growing and what's thriving. Creative stealing is always a good way to manage a garden. Or hire an expert.

We have a responsibility to leave the planet in better shape than we found it. So get outside as soon as you can and get growing.

Marjorie Harris has been gardening for the past 40 years in her own backyard; written 15 books about Canadian gardening including Botanica: North America: An Illustrated Guide to Our Native Plants, and most recently Thrifty Gardening From The Ground Up. She is a garden and plant consultant, garden writer and columnist for the Globe and Mail. She lives and makes gardens in Toronto. See: www.marjorieharris.com and marjorieharrisgardens.ca. Follow her on Twitter: @Marjorie_harris.