Irises are among the top favorites for garden enthusiasts due to their appealing blooms which come in a spectrum of colors, and a pleasantly mild floral aroma. Generally, most iris variations start to bloom from late spring up to early summer, adding an aesthetic pop of color to garden spaces, and also make a superb choice for flower vases.
Irises may require minimal care compared to other flowers, but understanding the right time and the correct method to trim them is crucial for the plant’s wellbeing and longevity. Cutting back irises is a key gardening practice that garden enthusiasts use for optimum plant health and top performance.
Cutting back irises has several valuable benefits. It encourages abundant blooming and provides a significant control measure against diseases and pests. Fungal and bacterial pathogens, such as rust and leaf spot, are known to affect irises, leaving their mark on old foliage. In addition, a notorious iris pest, known as the iris borer, often lays its eggs on the leaves to endure the winter.
There are several instances that necessitate the cutting back of irises. The most common ones are after they bloom, before winter, during division, and when the leaves start to wilt or turn brown. It is recommended to clean your shears with warm water and soap or wipe them down with an alcohol rub to prevent disease spread before you start the cutting process.
Directly after the flowers fade, trim the flower stalk at its base on an angle using a sharp pruner. Ideally, avoid cutting back healthy foliage until it’s fall. The foliage plays a crucial role in processing sunlight and carbon dioxide into glucose and oxygen. This conversion process helps to make larger rhizomes. A rhizome is actually a horizontally thick underground stem that can store the food produced by the plant’s leaves; the larger the root, the bigger the iris bloom and better the vitality of the plant in the next year.
Right after a frost but before winter begins, prune the iris foliage back 6 to 8 inches above the ground. Making an angular cut rather than a straight cut, similar to a fan shape, allows water run-off which prevents diseases initiated by excess moisture. The process also shields the plant from certain pests and diseases such as the iris borer.
When the foliage is unhealthy, it’s best to cut off leaves that are brown, yellowing, streaked, or spotted as close to the ground as possible. Unhealthy leaves can be a sign of lurking pests or disease. After discarding unhealthy leaves, make sure to inspect the rhizomes. If they appear soft, slimy, or unusual, it’s best to remove them and discard them in the garbage as they can potentially spread disease.
Iris leaves should also be cut back one-third of their length before digging up the plant or after dividing it. The ideal time to divide the iris plant is within 4 to 6 weeks after they bloom. This gives the plant ample time to grow a strong root system before winter.
During late summer, iris plants can appear messy and might even flop over. If that happens, it is best to cut the entire plant back. This promotes better air circulation around the rhizomes and prevents potential rots.
Keep in mind that healthy irises multiply rapidly. To prevent overcrowding, you should plan to divide your irises every 3 to 5 years. Overcrowded irises may lose vitality and stop blooming. Moreover, proper cutting back is necessary to prevent the iris plant from producing fewer blooms and becoming susceptible to diseases and pests. Lastly, it is best to trim your irises after a hard frost, which typically occurs in October. Doing so is key to maintaining your irises’ abundant blooms and overall health. Proper cutting ensures that they remain the star of your garden.
