It's time to scratch the planting itch. Before you run out to the garden center and hand over your plastic, it's a good idea to have a buying strategy. Here are some suggestions.

Get to the root of it. Before buying a plant, especially a pricey perennial, gently pull it out of its pot and check the roots. Are they plump and white, or brown, rotted, and stinky? You can expect most plants to be root-bound in their pots by now, so that shouldn't put you off from buying, as long as the roots look healthy. On the other hand, if you're considering a larger–and more expensive–container, checking inside the pot will tell you if you're actually paying for more plant, or if the plant's roots only extend a couple of inches into a big pot. In the trade, they call that "buying dirt", and it's certainly not a good value.

Pick your day carefully. Most garden centers gear up for big weekend sales by bringing in fresh inventory mid-week. That usually means that early in the week, pickings will be slim, and at the big box stores the plants probably won't have been watered for several days. Lots of casualties out on the shelves, the dead and the dying wilting in their little pots. On the other hand, going plant shopping on a weekend is garden masochism, just you and a thousand desperate gardeners fighting over the Big Daddy petunias. Best bet: go on Fridays, when the shelves are fully stocked and the inventory is in prime condition.

Check the cottage (garden) cheese. Careful shoppers at the supermarket check products for their expiration dates. Although plants don't carry expiration dates–if they did, they would most definitely be three days after you planted them–there are fresh plants and not so fresh plants. All those parched, leggy impatiens left over from last weekend stays on the shelf, supplemented by new shipments. Just like at the supermarket, it pays to shunt aside the weary products in front and go digging for the good stuff. Look around you; sometimes the newer plants are on the ground or the lower shelf below the display table, or they may be on a large cart off to the side, awaiting shelf space.

Size matters. Usually, you get what you pay for (but see "buying dirt", above). Given my druthers, I'd rather buy several four-inch pots of lobelia than a flat of little cells. The root systems are better developed, and in the interest of Time is Money, you will save a lot of time and effort in transplanting 6 larger plants rather than 48 little seedlings. While this is true of annuals, it is even truer when it comes to perennials. If you've ever mail-ordered a hosta, and received a 3-inch tall plant that took four years to attain even dwarf status, then you know what I mean. Not only is it esthetically disappointing, but given our potentially harsh temperature range, perennials planted in Chicago need to be sturdy in order to survive. Buy the biggest plant you can afford, now.

The Beijing rule of shopping. Years ago I went on a three-week trip to China. The first stop was Beijing, and the very first day there our government guides herded us into an enormous government-owned shop, where you could buy anything from Great Wall snow globes to fur coats to room-size silk rugs. A lovely gold necklace caught my eye, but because it was Day One and I was certain we'd be visiting a dozen more government-owned shops with identical merchandise, I stifled the urge to buy it. Of course I never saw that necklace again. At the garden center, there's little risk that you won't see red petunias or yellow marigolds coming and going, but maybe not the odd plant that makes you smile. When you see that really unusual begonia shaped like a snail, or the variegated abutilon that would look just perfect in your patio urn, go for it. Tomorrow–maybe even in ten minutes–it may be gone.

The Shanghai corollary of shopping. You've estimated that you need two flats of impatiens 'Elfin Coral Sparkle with Purple Eye' for your front yard, so that's what you buy, right? Wrong. Buy an extra dozen plants, at least. If matching up colors is important for your space, don't cut it too close. Some cells in the interior of the flat may be empty, some plants may bite the dust tomorrow, your spouse may have underestimated, and in any event you'll always find a place for the extra seedlings. Tomorrow, that one color of impatien will be the only one that has sold out, guaranteed.

Read plant tags carefully. No matter what the helpful little sign on the display table says, pull a plant's tag out of the soil and read it, every single word. You're looking in particular for highly technical buzz words such as "sun" and "water". Like real estate, gardening is about location, location, location. If you have shade, then don't expect miracles from lantana. If your soil is soggy, plants like pelargonium (aka geranium) will refuse to deal with wet feet. Beware of certain stock tag phrases, like "heat and drought-tolerant" (don't plant it before the temperature turns tropical, or it will perish), "needs constant moisture" (needs more water than any of us will ever give it), "fast-growing" (invasive), or "potentially invasive" (don't even think about it). When buying perennials, check the zone information, and even if it says hardy to Zone 5 (most of Chicago), give it pause. The more expensive the plant, the more reason you should go home first, google it, and then decide, Beijing or not. Or if you're lucky, the garden center's perennial expert will truly be an expert.

Nip it in the bud. Don't be seduced by plants full of blooms. In fact, those are the ones that you do not want to buy. Root-bound annuals start putting their energy into producing flowers, because there is nowhere else to go. Tomato and pepper plants will do the same thing, flowering and even fruiting on the store shelf. What you will end up with is a stunted plant with the dreaded leggy growth and few more blossoms. Large-flowered bedding plants like pelargonium can be slow to rebloom, so the plant you take home covered in rosy petals will be pretty for a few days, then will be naked for a few weeks hence. I look for plants whose flowers are just starting to bud out, with perhaps one or two blooms. (The blooms are useful if you are concerned that the garden center has been playing it fast and loose with its tags, and that the allegedly pink Wave is suspiciously close to its purple siblings on the shelf.) If you absolutely have no choice and every plant is in full bloom, then pinch off the buds when you get home. Not only will the plants put down healthier roots, but also you will be rewarded with fuller, bushier plants later.

MaryAnne Spinner, Chicago Master Gardener

Do you have a gardening question? Email the Extension's Electronic Plant Clinic at rwolford@uiuc.edu, and our Master Gardeners will be glad to assist you.