Humans are happiest with growing things around them. Even office pot plants reduce the number of ''sickies'' taken each year. Schools with many trees may not get the best academic results. But where would they stand on a happiness index? I wonder.

So what makes us happy about gardens?

Green leaves

Even greenery in shopping centers cuts down the rate of vandalism.

Plant LOTS. If you can see the fence, your garden is too bare.

Add a pergola over paving, with grapes or hops or kiwi fruit that will cover the area with greenery in summer and lose their leaves in winter. Of these, hops are the least messy, as the leaves wither up and mostly blow away, and kiwi fruit the most messy - their thick tough leaves drop through autumn and most of winter and the fruit can get a bit sludgy too.

Scent

Most flower scents raise your spirits, but so does the smell of newly mown grass, wet leaves and all the million subliminal odours from a garden. (There is a theory that it's the lack of these smells as much as the lack of sunlight that may trigger seasonal depression in winter).

I can pretty much tell the season here by the scent: winter daphne, Earlicheer daffodils, a multitude of spring blossom, including wattle, then the hybrid musk and other scented roses, ripe tomatoes and apricots, the magnificence of a whole bank of ginger lilies in full perfume, the late summer scent of curry bush, ripening cumquats and tangelos in early winter, the joy if someone gives me a bunch of sweet peas …

Colour

All of us have our favourite colours, the ones we like to wear and are happiest around - and those are the colours you need in your garden.

You can find flowers and fruit in any colour if you look hard enough, even blue (Blue roses, cornflowers, the blue flowers of garlic chives). I love purples, and deep purple red. But the colours I love in the garden change with the season: white and cool blue salvia in summer (though I am married to a man who hates white flowers). Red hot pokers are too garish in summer, but in mid-winter they are deeply cheering, to us and the spinebills. I love the rich orange of citrus in winter too, and then the pinks of spring.

Water

The sound of water is relaxing, the smell of water lifts your spirits, the look of water - trickling, splashing or birds playing in it or just drinking - is one of the joys of a good garden.

We have a tiny pond - well, I say it’s ours, but the wombats, wallabies and birds would debate that. Or not bother, as it is so clearly theirs. After all, when was the last time I drank from it, or bathed in it? It’s fed with a single, small dripper, just enough to keep it full after it’s drunk from and some has evaporated.

Something to eat

Humans feel secure with food about them, especially kids. Have at least something you can eat growing nearby, the easy care kind, like mulberry trees, passionfruit vines, kiwi fruit vines, Vietnamese mint, or a fringe of garlic chives to edge the garden. They are flatter and coarser than common chives, but great in stir fries, sandwiches and salads where you want an onion/garlic flavour.

Plant some easy herbs like oregano, rosemary, peppermint, pineapple mint, winter savoury, marjoram and thyme and you've got scents as well as tucker, and green leaves.

Your fantasy

Mine is wombats out the window, and kids laughing down at the creek as they kick a ball around, or lie in the shade eating mulberries while they read a totally fascinating book.

What garden do you dream about? Formal roses? Whimsical topiary? A backyard cricket pitch?

It makes you happy, the birds happy, the world in general just a little happier … plant it!