Or, perhaps we should say Tuin Up; I believe Tuin is Dutch for garden. By mid-summer, much of your garden is feeling a little dragged out. Hot days and warm nights are tough on plants as well as people. A little pruning back can be just the ticket to rejuvenate annuals and perennials. I’m not your guy for vegetable garden hints, I have a shady yard.
Let’s start with hanging baskets. A couple of things happen over time, both a factor of the concept that, if a plant is still alive, it’s trying to grow. (That which doesn’t kill it, makes it longer.)
Hanging Baskets: Basket plants should be sheared or selectively pinched to keep them in proportion to the pot. Petunias, for example, will trail down the side of the pot, growing and flowering from the ends of the stems, until you have flowers at the end of 18 inch long stems with few leaves or flowers at the top around the basket.
The best thing to do is selectively cut off about 20% of the stems each week or two right at the edge of the basket. As those stems recover and start to grow and make flower buds, you cut the next 20%. Over time, you keep the plant to a manageable length and it never looks like it was cut back. For an upright plant, do the same thing–just pinch random stems back from say 12 inches long to 4 inches long, once every week or two.
As the basket ages, the plants roots slowly fill the soil in the basket. The soil settles, washes out of the pot, decays…at some point you have more roots than soil. Roots don’t hold water like soil does. If you find you are watering a couple of times a day, it may be time to put the plant into a larger container– maybe no longer hanging– or in the ground.
Perennials: The best reference is The Well-Tended Perennial Garden, by Tracy DiSabato-Aust. She tells you how and when to cut back or shear plants in your perennial garden in order to control height, or to prepare the plant for another surge of bloom if it’s a rebloomer like most of the summer-blooming perennials are. Tracy is a landscape contractor in Ohio, and the book is written from practical experience and for the average gardener.
Annuals: Cut off old flower heads to encourage rebloom (deadheading) or cut back the plant part way to encourage bushiness and branching (and eventually more flowers). If you are happy with how they look, don’t do anything. Vinca and Supertunias probably don’t need any attention at all.
Herbs: Continue to pinch off the ends of the stems to encourage bushiness. With basil, remove flower buds by pinching out the flowering stems. If you have a few strong stems that have not gone to flower, take a 3-inch- or-so long tip cutting (the end 3 inches of the stem) and put it in a glass of water so that the bottom inch or so is in the water and the top is in a sunny window. It should root in about 10 days. In two or three weeks, you can plant it back outside while your older basil flowers and declines. The water glass should be dark; dark colored, or wrap it in foil. You can do that with coleus, too.
Weeds: Pull them out, they are just going to get bigger and meaner.
by Larry Hurley, Behnke’s Horticulturist