Gardeners, a horticultural pal of mine has always said, are an inherently thrifty bunch. Some of us will pay a hefty price for a particularly good pair of secateurs or boots, but in general, the car boot sale spade can be a trusty companion, certain perennials exist to be divided, and seeds are to be saved, swapped and sown. I think that’s why all the plastic tat sold in garden centres – often with a tenuous connection to gardening, at best – winds us up. As one particularly old-school garden writer once espoused, plonking annuals in a window box isn’t gardening, it’s shopping.

Still, there are certain commercially minded events that I look forward to with the same fervour I did the Clothes Show at Birmingham NEC as a teenager (if you know, you know); this month is particularly good for them.

This weekend is the Great Dixter spring plant fair. The flamboyant and experimental East Sussex garden – initially created by Christopher Lloyd in the 50s and now masterfully looked after by Fergus Garrett – is modest about what it calls a “small plant fair”, but it’s one that many plant-nerdy designers and gardeners I know carve space for in their diary. Dixter gathers offerings from specialist nurseries, and this year is even offering to test your soil under a microscope while you’re at it.

Next weekend, many of the same nurseries will squeeze in and around the Garden Museum in London for its spring plant fair. Advance tickets always sell out but there is room for those prepared to queue at the door.

Sadly, I won’t be going to either, as my garden’s about to become a building site, but I guarantee I’ll be there next year. A bit like navigating an antiques fair or a foreign supermarket, shopping at a plant fair, can be as overwhelming as it is exciting. It’s easy to be led astray.

I like to make a list of pockets of my garden that need new planting. Perhaps it’s that tricky dry shady patch under a tree, or the boggy corner where everything dies, or a new sun-kissed terrace. Take note of how much space you need to fill and what else is growing there; these are questions you’ll likely be asked if you speak to the stall holders (which is crucial: there is so much expert knowledge to be absorbed).

Keep your colour scheme in mind. If you’re not sure of what your colour-scheme is, think about your favourite plants in the garden and use those as a guide. Never buy just one of anything. Buy in odd-numbered multiples: threes, fives, for rhythm and repetition in your beds. Finally, acknowledge that you will break most of these rules for a really remarkable find. That’s part of the joy.