Fielding Questions: Cutting back geraniums, pinching tomato blossoms and fall tree pruning
Q: I attached a picture of a planter containing old-fashioned red rose, apple blossom and tulip geranium plants that are really large. They’re 2-year-old plants that I grew from cuttings. Can I cut back these mother plants back to about 3 inches after I harvest the cuttings for next year’s plants? Would I need to cut them back again in February? — Dick Cuddihy, Moorhead.
A: You’ve got some wonderful, precious, old geranium varieties. The red rosebud, apple blossom and tulip geraniums are heirloom types with beautifully unique flower forms. These types, like all geraniums, can be rooted from cuttings in early September and grown through the winter for fresh new plants ready for next spring’s pots and planters.
The mother plants can also be saved, of course, and are best cut back in fall as you take the plants indoors for winter. Cutting them back to about 3 inches is ideal, as it removes much of the old summer growth and stimulates fresh new sprouts that will keep the plants vigorous. In February, pinching back the winter growth makes the geraniums well-branched in time for mid-May planting outdoors once again.
Dick continues his geranium story: “Last winter I started over 125 new plants in 6-inch pots that I was going to give to friends in spring. The geraniums did great over winter, and I moved them outside last spring. On the third day I put them in a spot under my outside deck, but one night the deer ate every one of these new plants, roots and all! All that work and care down the drain. Luckily, I had the mother plants on top of my deck and the deer can't get up there. I have a cool room facing south that has 12 feet of windows and that is where I put the geraniums for winter growth. Next spring I’ll be sure to protect from deer.”
Q: My tomatoes are still flowering. Should I be pinching off the flowers now that it's September? — Ron Boe, Fargo.
A: In early September, large-fruited tomatoes probably won’t make it from flower to ripe fruit, especially now that temperatures have cooled. Cherry tomatoes might ripen, if the rest of the season is warm and frost is delayed.
Pinching off the blossoms and pruning off the tips of vines to prevent new growth will help divert the plant's energy into ripening the fruits that have already formed, instead of spending energy on fruits and foliage that have little chance.
Q: I hate mowing around the low-hanging branches of our apple tree. Can I trim up now? — Don Jelinek.
A: Most tree pruning is better delayed until early next spring before new growth begins. In fall, tree cell growth is slowing, as trees instinctively slow down in response to shortening days as trees ready themselves for winter. Slower cell growth means pruning cuts are less likely to heal rapidly, leaving open wounds going into winter.
Pruning fruit trees during summer and fall can also create open wounds through which bacteria and fungi can enter, increasing potential of spreading diseases like fireblight and fungal rots. Bacteria and fungi are easily spread from cut to cut on unsterilized pruning shears. Pruning during late winter and early spring, while organisms are still dormant, decreases the likelihood of spreading these pathogens.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at firstname.lastname@example.org or call 701-241-5707. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.