Why Some Plants Just Don't Grow
Check the roots before you plant.
You think you did everything right. You purchased a healthy tree or shrub, picked the perfect spot, dug a nice, big hole, planted it, watered it, mulched it, and even fertilized it. But it just sat there all last year. Oh, it might have added a new leaf or two, but still seemed frozen in time. After nearly a year in the ground, it's no bigger than when you planted it. Why?
Maybe you should have checked the roots.
Many plants grow in the same pot for months before somebody buys them. The pot doesn't get any bigger, but the root system does. Pretty soon the roots wrap around each other to form a solid pot-shaped block. After planting, the roots keep on strangling themselves and don't grow out into the surrounding soil. So you get a stunted plant that seems to want to stay small forever.
That's why you should slip a potted tree or shrub out of its container – if possible – before you buy it. Finding that the plant is rootbound doesn't mean you shouldn't buy it. It means you should loosen the roots before you plant. There are two ways to do this. One, use a pencil, screwdriver, or a stick to gently loosen the outer roots, so you can pry them away from the ones inside and have roots growing in every direction. Two, lay the plant on its side and use a trowel, knife, or shovel to cut through the middle of the root ball, cutting one-third of the way up from the bottom. Use your fingers to pull the two halves a couple of inches apart, set the plant in the hole, and plant.
WATCH: Planting Azaleas with the Grumpy Gardener
"Oh great, my stunted plants are already in the ground!" you scold, seething with resentment. "Guess it's too late for them now, huh?" Oh, ye of little faith! If you suspect your plants were root bound when you planted them last year, dig up them up now while they're still dormant and check the roots. If you find they are, loosen the roots and replant in a hole twice as wide as the original but no deeper.
Another mystery solved! I should get paid big bucks for this.