Off With Their Heads

Continuing from last week with our look at disbudding and deadheading—it’s at this time in the gardening season, the dog days, that the violas and pansies are looking a bit ragged and stretched. If they’re growing in a spot where they are protected from afternoon sun and the “spent” flowers are pinched off religiously, they may bloom all summer. However, give them a hard pruning with a shears or scissors and remove about half their growth, and they may rebound with surprising vigor as long as you keep them watered. There can be a downside here that has to be a consideration when deadheading some plants. I depend on my violas to self-seed between the cracks in the pavers on walkways and patios. If I continue to disbud them they won’t drop seed, and there will be fewer plants showing up next spring from this summer’s dropped seeds. One solution is to leave a few leggy stems so that the seed will set, then drop to the ground for reseeding.

Other annuals, such as cosmos, salvia, snapdragons, zinnias and non-hybrid marigolds and petunias and geraniums—especially the hanging types—will also perform at their best if they are deadheaded regularly and not permitted to set seed. Again, if they are F1 hybrids they are often sterile and it’s not necessary to deadhead, so knowing your annual’s lineage comes in handy. Conversely, if they are not hybrid and are allowed to drop seed you can find your patio, garden beds or pea stone driveway covered with petunia seedlings the following year. This can be a very interesting effect, but it can also drive the anal retentive type of gardener to become suicidal. It also results in my getting emails about perennial cosmos that “overwintered” when in reality they just dropped seed that germinated the following spring.

Perennials like lupines, foxgloves and delphiniums may (may being the key word) also rebloom if deadheaded. In the case of delphiniums they may even try to rebloom in early fall, but it’s my experience that delphs that are encouraged to flower late in the season are the ones most apt to overwinter poorly. Digitalis (foxglove) seed allowed to fall to the ground and not get covered by soil or garden debris can result in these plants self-seeding and thus perpetuating though they are short lived. But lupines will germinate only if the seeds are buried below the soil.

The practice of cutting back is probably best demonstrated with catmint (Nepeta). This perennial will bloom prolifically through the spring and early summer, but the taller varieties do tend to get leggy and eventually topple over or cascade into a stringy tangle of fragrant but untidy foliage. When this happens you can get out the shears or scissors and cut the plants back to 6 to 10 inches above the ground. Several weeks later the plants will fill in again and rebloom, though this bloom is not as heavy as earlier in the season. If left unpruned this perennial may also self-seed and show up next year in the lawn and garden. Gaura and Aegopodium can be handled the same way.

The most common example of disbudding is done to the perennial chrysanthemums. From the time they first set buds until the Fourth of July the buds can be gently pinched or rolled off. This encourages bushiness and masses of flowers instead of taller plants with fewer flowers. Commercial nurseries do this with chemicals that stall the formation of the buds, and many of the newer varieties claim not to need this, but in the home garden disbudding is the preferred method. Disbudding, however, will delay flowering, so if you have been in the habit of seeing a particular mum bloom in the end of September and you disbud one year, don’t be surprised if it blooms later. Mums are also very sensitive to day length, and some of mine grow in partial shade. I disbud them to keep them “tight,” and while the shade makes them want to bloom earlier, the disbudding makes them bloom later. But disbudding of mums too late will simply result in no flowers at all.

Those who grow mums and tuberous dahlias for show and competition will disbud the stems so that only one bud is allowed to develop. The result is a single flower that is much larger than if several buds on the same stem had been allowed to grow on. There is also a relatively new series of mums call the Igloo series. Many of these will bloom in late July and again in late September—but not if they’re disbudded.

Many rose growers will disbud their plants in the spring and some through the season in order to produce fewer but larger flowers. This is most common on the hybrid tea roses, where the side buds are removed, while on floribundas and grandifloras it’s the terminal buds that are often removed. Disbudding on our rugosa roses down along the beaches and bays is not done, as these plants are grown for high flower numbers, not larger flowers. Pruning roses during the growing season is another topic though and should be considered when you decide on what types to plant. Some are actually carefree and don’t require disbudding or pruning during the growing season.

Now, if disbudding works so well, why not use it on vegetables and fruits? Well, to some degree we can and the principle is the same. If you remove one or more of several flowers the fruit or vegetable that develops as a result will be larger, sometimes. Disbudding a cherry tomato plant will not cause the remaining buds to develop into beefsteak-type tomatoes. Disbudding doesn’t change genetics, it only allows a particular bud to grow to full potential. Having said that, though, I know gardeners who will remove some of the flowers on zucchinis and cucumbers so that fewer and better fruits develop. This is also a common practice among those who try to grow competition-size pumpkins. Here they are looking for seed from genetically superior parents that have exhibited largess in earlier crops. The ability of the vines to produce the largest possible pumpkin is then enhanced by reducing the number of buds on a vine so that all of the plant’s growth potential is focused on the one pumpkin rather than the several that might have otherwise developed on that vine.

Fruit trees are often “thinned” either manually or chemically so that fewer but higher quality fruits develop, and among herb growers cutting back the early growth of a number of herbs results in bushier, more productive plants with more foliage. While this is more akin to pruning it’s usually just considered “cutting back” and discussed along with pinching, disbudding and thinning.

It’s a bit late for some of the plants we’ve discussed, but take a walk around the garden to see what you might be able to work on now and make a mental note of what needs to be done earlier next year. And no matter what you do … don’t remove next year’s buds that are now forming on shrubs. And of course, keep growing.