As with all types of gardening, for container gardening it’s important to start with healthy plants. This helps your container plants reach its full potential earlier in the season. Healthy plants bounce back faster after the inevitable traumas they encounter when moving from their small, temporary cell packs or pots to roomier quarters. Healthy plants also have more resources to muster if they need to thwart pests or diseases.
Healthier doesn’t necessarily mean larger or more mature. Sometimes older, larger plants take longer to recover from transplanting or they may be potbound, which slows a plant’s growth. However, we need to balance these considerations with our desire to have full, lush containers as soon as possible after planting. Therefore, you may want to use plants in four-inch or larger pots, rather than plants that have spent too long in cell-packs. Larger plants are also preferred for spring or fall containers, which will have shorter runs.
What to look for when buying plants
When buying plants grown in cell packs (shallow, plastic rectangles divided into four or six sections), look for stocky, well-branched plants with flower buds, not full-fledged flowers. Plants already in bloom in these small cells are expending a lot of energy, which you’d rather they expend after they’re planted in their permanent location. If you’re concerned about getting exactly the right color of pansy or petunia, find a flat that has a few specimens in bloom just to verify that it’s the color you’re after. Don’t rely on labels because the plant tables at garden centres in early spring are chaotic, and labels get jostled into the wrong spot.
Pass on tall, gangly plants, or those with dull, grayish leaves. They’ve probably been stressed by drought, crowded growing conditions, deprived of light for too long or experienced sudden extremes in temperature during transport from wholesale grower to retail shop. Obviously, plants with spotted, chewed, yellowing or dropping leaves aren’t a bargain, either.
Sometimes cuttings are rooted by inserting the cut end in a small cube of florist’s foam, which is then planted in a small pot. Check to make sure the cube isn’t half exposed and dried out; the cutting may have too few roots to sustain transplanting or have suffered from drought.
With large plants, check the bottom of the pot. If a matted mass of roots is struggling to escape from the drainage holes, the plant has probably spent too long in a small pot, and its growth may be stunted. If this is a must-have plant, however, you can salvage the situation by running a sharp knife down the sides of the rootball, slicing it in three or four spots, before planting. This bit of tough love helps stimulate new roots to grow. Trying to untangle the root mass by hand usually creates too many jagged tears in the roots, which invite disease.