Catalogs, magazines and online garden articles have been hounding us for a month already: Buy these plants for a better garden next season.

That message, however, puts the cart before the horse. First, plan what you are going to do for a better garden season, before deciding what to buy.

When gardens disappoint, the fault is rarely in the plants and usually in the gardening.

Purge ruthlessly: As a young plant-hugger I did not heed Vita Sackville-West’s advice that if you don’t like a plant in your garden, “hoik it out.” Perhaps I thought there would always be new garden beds when the old ones overflowed, or lots of gardening friends would appreciate my extras. I certainly didn’t just yank a so-so performer and compost it. But we should all do just that.

Why? No one can afford to tend a bunch of mediocre plants indefinitely. While perennials take at least three years to show their habits and qualities (and woody plants even longer), at some point it is clear that this plant in this location is not a winner. Either you just don’t like it or it does not work because of size, color, whatever. Move it, share it or compost it.

In case you think I’m advocating the whimsical tossing of $11.99 perennials because you don’t care for the shade of pink, I will modify this advice slightly: Location is everything. If it’s a decent plant, try a different location before giving up on it. Ideally, try a new perennial in two or three garden locations, as I once did with Rodgersia. It grew 1 foot tall with puny leaves in good soil in a lightly shaded border, but the one in the soggy bed in deep shade is a lush 3-foot giant. If I’d only planted it in the first spot, I would have hoiked it and never known the plant.

Divide and share: Frankly, plant exchanges are overrated because most people give away plants that spread too much or are now available as better species or cultivars. (Heirloom collectors and sentimentalists, yes, I know we must preserve the diversity of the gene pool and many traditional species are exquisite.)

Still, most gardeners would be better off passing on your old ‘Sunny Border Blue’ veronica or goose-necked loosestrife, and choosing a newer, bluer veronica and a ‘Miss Manners’ loosestrife.

Dividing perennials can be done wrong in two ways. Doing it too early in its life can endanger the plant or set it back severely. Garden center customers often see a pot with a full root system and ask, “Can I divide it?” Usually the answer is, “Not yet.” The plant needs a couple of full seasons to establish its root system and recover from the shock of moving from a pot to the garden.

Later, the common error is not dividing or thinning thoroughly enough. Divide a clump of perennials more severely than your inclination. I have never yet been sorry I took out too much of a spreading ornamental grass or perennial clump. Then give it away – if it’s worthy – or compost it. (Kind plant lovers, remind yourselves that the natural end of a plant’s life cycle is to decompose and become part of the soil that feeds new life.)

A soil improvement plan: This mental exercise (and eventually the real process) of evaluating, thinning and dividing garden plants has left you with blank spaces – opportunities for new plants! But first, it is time for soil homework.

Almost nobody has naturally deep, rich topsoil, or ideal planting mix, unless you have had the luxury of professionally prepared beds. So you must amend the soil every spring – and every time you move plants or add new ones. Put organic matter, usually in the form of compost, under, next to or on top of all the plant’s roots.

In the case of the recently thinned flower or shrub garden, pull back the mulch, loosen the soil around the crowns of existing plants and spread an inch or two of compost. (Put mulch back if you wish.) For new plants, work a lot of compost into bare soil, and plant into a generous compost/soil mix.

Finally, new plants!: First, choose your sources. For most gardeners, catalogs are not necessary or your best. In remote villages in Iowa, sure; you can’t find a garden center with more than 30 varieties. Plant collectors and specialists, sure; you do need the catalog to find a particular Orienpet, Arisaema or daylily.

But in Western New York we have garden centers and nurseries with CNLPs and educated professionals, who spend the winter choosing, growing or tending superior plants for this region. Tell them what you want.

Second, species and cultivars: Native plants and some tried-and-true species are often the best for many reasons. Every new cultivar is not a true improvement. Yet, for a bang-up flower garden, many cultivars are indeed better and longer performers. So it is not easy to choose plants for those blank spots in the garden.

My final advice for your better 2013 garden: Do the planning, take your time, prepare the site and choose carefully. Then, if you’re wrong, hoik them out!

Sally Cunningham is a garden writer, lecturer and consultant.