by Tom Stebbins
Give Your Plants a Pinch
Pinching plants will not put you in jail for cruelty to petunias. Pinching is a form of pruning that experienced gardeners use to their advantage. The term “pinching” comes from the fact that gardeners actually use their fingers to pinch off the tender new growth at the terminal end of the stem. The index finger and thumb are used to crush or pinch off the growing tip. About an inch or less of the tip is removed. Usually a sharp fingernail helps in the pinching process.
Why pinch
Plants are naturally trying to grow taller. They stretch toward the sun for their survival. Gardeners don’t always like tall lanky plants. They often prefer more compact and fuller looking plants. Call it discrimination if you want. Cheers for the short stocky individuals. Pinching plants forces the plant into a fuller form. One pinch causes the plant to grow twice as many stems. For herbs like basil, pinching back can help the plant produce many more desirable leaves.
Pinching also keeps a plant compact. It forces the plant to focus on regrowing lost stems, rather than growing height. Sometimes nature performs a natural pinching. A late spring freeze nips off the tender growing tips. This causes the dormant buds to open up and replace the lost leader. Insects chewing and leaf diseases can cause the same thing to happen. The plants have these extra buds in reserve just in case there is damage to the terminal buds.
Plant hormones
Similar to humans, plants have many hormones which regulate growth. Two primary plant hormones are auxins and cytokinins. Auxins are produced in leaves and stems. Cytokinins are produced in the roots. Knowing how these chemicals work enables gardeners to do magical things with plants. The rooting hormones sold at garden centers often contain auxins which will stimulate rooting in leaf or stem cuttings. It is the high natural auxin concentration in the tip which causes a plant to grow tall. This is called apical dominance. Pinching temporarily reduces auxin which takes away the apical dominance. This enables the side buds to start growing.
Proper pinching
A plant should be pinched back before it is begins to flower. For example, gardeners can pinch back chrysanthemums in midsummer. Start by pinching back the tip of each shoot when the plants are four or five inches tall. Pinch back the plants every time the side shoots grow four or five new leaves–about once every few weeks. Stop after around the first of July. Once the days become shorter mums will form flower buds. So the plant will grow more lateral branches that will produce more flowers.
Other pinches
Pinching out is also the term used when small side shoots are completely removed. This is done when single stems are desired instead of multiple shoots. Now is the time to pinch out soft green side shoots on dogwood, crape myrtle, maple and many other woody plants. Once they grow tough and woody these shoots will have to be pruned out with metal tools.
On grafted roses, any green stems that grow below the graft union are called suckers. These should be pinched off or rubbed off because they sap energy from the plant.
Deadheading is a form of pinching. It happens after blooming. Deadheading removes spent flowers and developing seed pods. This causes the plant to stop expending energy on old blooms. It redirects nutrients to new growth and eventually more new flowers.
Insects can often be controlled without pesticides if careful scouting and removal is immediate. In many situations the critters can be pinched with your fingers or pushed into a can of soapy water. Wearing gloves during this pinching operation is optional.
Fingers are amazing gardening tools. In many cases they are the only tools that can accomplish delicate and precision operations in the garden. So go ahead and pinch your plants. They won’t scream too loudly.
For more Hamilton County gardening information and calendar of events go to www.mghc.org