Ditch the gym and get gardening - your body and brain will thank you

Head out into the garden instead.

Every decade or two someone comes up with the same research result: for physical and mental health, long life and less cognitive decline as you get older, become a gardener. Now, or as soon as you have finished reading this.

Gym junkies exercise certain muscles. So do joggers, jarring their knees and their spines as they go. Gardening exercises every part of you, from your brain to your stomach muscles, toes and fingers. An 80-year-old gardener looks as sturdy as a backyard dunny, with solid shoulders, hips and knees.

I learned gardening from elderly people. Mr Doo was in his 80s, Jean in her late 70s, and all the others well past retiring age too. It's only just struck me that this wasn't coincidence, nor was it because old gardeners are wise gardeners. People who garden live longer, and keep greater mental clarity.

A garden needs so many kinds of jobs, from mowing and whipper-snipping to trimming the hedges or pruning the roses or grevilleas . Yes, do prune your grevilleas and other native shrubs. They may grow happily with no human help in the bush, but they'll look twiggy and scrappy in the garden if not pruned once or twice a year. How much of each bush needs to be pruned off ? There's a different answer for each species - which is another reason gardeners do so well. Gardeners accumulate knowledge every day. They also learn to notice their surroundings, and the changes in their surroundings, living in the present rather than vicariously via a screen.

It is quite possible to have a gorgeous designer garden of "low work" bulbs, agaves, succulents, tree ferns, dwarf magnolias, crab apples, flowering plum trees, non-invasive bamboo or agapanthus, grasstrees and groundcover roses that needs nothing but watering and the attentions of a paid gardener once or twice a year - spring and autumn are best - for pruning, replacing and slow-release feeding.

That's not gardening. It's exterior decoration, and I'm all for it, especially if your passion is to go bushwalking or teaching kids dance at weekends instead of mulching the camellias. The world needs more greenery, which is an excellent reason for paying someone else to transform your plot of land.

But do-it-yourself gardening gradually accumulates odd bits of knowledge. Put tea bags in the pond to stop algae. Feed the lemon tree with tea leaves, coffee grounds and a weekly "tree wee" by any male old enough to toilet train. Put metal collars around tree trunks, rose bush stems and pergola posts to stop possums munching and rats nesting. A spray of milk fortnightly from midsummer to autumn will stop downy mildew curling up your grape leaves. Bleach will kill the slippery moss on paving. Don't bother planting tomatoes till Melbourne Cup Day, or carrots after Easter, and complete winter plantings by the end of March.

This accumulations becomes 'cognitive reserve'. If/when if your brain declines, it will be so dense and complex that you'll need a decade of decline before it's noticeable.

Most gardeners become bird watchers, too. Bird watchers also have resilient brains. I love watching the blue wrens and yellow robins follow Bryan around the garden, hoping he'll dig or pull up weeds so they'll find worms for lunch. Gardeners notice where the kookaburras nest. They tend to become best mates with the local magpies.

We become possum watchers, too. One of my joys last week was watching Possum X try to eat a particularly succulent bunch of crepe myrtle blossom. The branch wasn't sturdy enough for him to get to the blossom. Every time he tried, it bent, and he'd leap back to the trunk shrieking like a mob of feral pigs. In fact I thought the noise was feral pigs, till I went outside with a torch, realised the shrieks were coming from the treetops, and saw Possum X.

Gardening is fun. It can be solitary, or as a couple, or communal. Gym and golf club memberships cost money. A garden can save you money, or even make you money, or at least get you a free coffee at the café you supply with bunches of blooms. Gardeners also tend to be great cooks. Let's see what we can do with all this tarragon, and does adding a bay leaf really make a difference to the deliciousness of chicken stock? (Yes.)

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Consider giving grandma a raised garden bed for her next birthday, so she doesn't have to bend or kneel, or a garden kneeler, kind on joints but also with sturdy handles to help her on her feet again.

Give her some giant ornamental tubs of wood or pottery. Do not use pottery if you have lyrebirds, bouncy dogs or wombats. They'll try to climb up them or dance on them, which may overturn and break the pots. Add garden gloves that go all the way to the elbow, as older skin is thinner and more fragile, and slower healing too, plus gumboots if her garden is close to bushland and snakes regard the garden as home too, plus a broad-brimmed hat. On no account let grandpa wear a short-brimmed orange towelling hat. Give him a good gardening Akubra instead.

Many gardeners lose their passion when they move to a smaller unit or retirement village. The gift of a raised garden or patio pots can get them planting again, "borrowing" seedlings and cuttings to start a new garden, and possibly even organising a new garden club or community garden, both fulfilling.

You may even be the recipient of baskets of luscious tomatoes, plentiful snow peas or fragrant sweet peas as grandma scrubs the dirt out of her nails to make pumpkin scones, pumpkin soup and pumpkin bread, to use up her garden surplus, and feed you.