Gardening 101: store bought plants
In a few weeks gardening stores will have a wide selection of plants for you to take home. For most gardeners this is a chance to get a vegetable or flower garden started without the hassle of buying seeds and potting soil. But, stop and think for a moment. Are you really going to plant six zucchini plants? Twelve tomato plants? Twelve or eighteen pepper plants? What about the condition of the plants? Do they look healthy and hale? Are they thick and strong or tall and leggy? Do they look as if they are overflowing from the pot or is there adequate space?
When inspecting the plants, especially early in the season, take a careful look at the leaves. If the tips look slightly curled and white, the plant may have seen a touch of frost on its way to the store. This will retard its growth for a few weeks. If the plant has been under watered and has dried out, and the leaves look a little curled around the edges, plant growth has slowed and it will also take a few weeks to regain its normal growing rhythm. Cold weather and drought tell the plant to slow its growth and it usually takes six to eight weeks to get back on track again. So look for plants that have been sheltered at night, well watered, and are not too tall. Taller plants may not have had enough sunlight (or artificial light) and have stretched toward the light. That's ok with tomatoes, which you can bury up to the first set of true leaves, but most other plants don't like to be deeply buried. Also, when buying tomatoes, don't buy plants with flowers or tomatoes on them early in the season. The flowers or tomatoes will usually drop off because night time temperatures are not warm enough to sustain the fruit. Tomatoes need a night time temperature of around 55 degrees to set fruit and you want your plant to be large enough to grow the fruit when temperatures are warm enough.
Take a look at the pot the plants come in. Most seedlings for sale are started in what is known as a "six-pack." This puts six plants in an easy to carry container. However, most cells in each six-pack measure about 1 inch by 1 inch, which is not a lot of soil for growing pants and is only intended for the first six or eight weeks of the plant's life. When you buy plants in a six-pack, immediately move them into larger pots or plant in the ground or growth will stall and you be faced with slow growing plants.
Now we come to the subject of hardening off. Typically seedlings are started in greenhouses under artificial light (in the north), or they are trucked in from southern states. Plants need to be hardened off before they are set out in the ground. Hardening off means that the plant is gradually acclimated to our colder spring weather so that it will continue to grow at a steady rate. Unfortunately, most plants move from greenhouse to truck to garden center without much in the way of hardening off. It's you, the gardener, who pays for this with plants that grow very slowly for the first six or eight weeks in your garden. The best way to harden off store bought plants is to set them in cold frame or very sheltered spot for a few days, then transplant them into the ground. Fortunately, I am told that the plants that Secret Garden has on sale in the spring are hardened off and I know that they are well watered.
Later in the season, you may be tempted to buy bargain plants that are being cleared out. Often these are taller and have roots growing out of the pot. If they are perennials, that's fine. They'll die back over the winter and should be perfectly fine next season. You are buying these plants to last several seasons, so don't overlook a bargain because it looks ratty this year. If the bargain plants are annuals and are in flower, unless you want instant flowers, their beauty is fading and you are wasting money. If they are leggy tomatoes, as I said above, plant them a lot deeper. Tomato stems turn into roots when planted deeply. They just take longer to grow.
Finally, no matter what plant you buy, it should grow larger, so make sure you give it enough space, especially shrubs and trees. If you are unsure how much space a plant needs, go to the library and look up a full size plant, or find another mature version. Too often plants are crammed in too small a space.