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Cutting Back Perennials

Today I have been thinking about cutting perennials back after they bloom, and doing some of it too. Over the years, I have seen a number of plants cut back before they were ready, others cut back too formally, others not cut back at all when they should have been.

Take for example, Watsonias. I have them in several colors. They are plants that resemble Gladiolus, but taller, more graceful, with smaller, less frilly flowers. After the first flush blooms, you can cut the stem back and shorter side heads of flowers will open up. This happens 3 or 4 times before the plant is finished blooming altogether. Then you wait. The outer leaves begin to turn brown, and, because it is in the iris family, they are tough, best cut with shears at their bases. From here, you have the option of cutting the whole thing down in a few weeks when more leaves turn brown, or cutting them out as they form, but still having the green ones standing. It is best for the plant to let the leaves die back on their own before you cut them, and I'd never cut them until at least a third of them had turned brown, but you have some leeway here.

Another example is lavender. Its blooms are starting to lose their color now, and so soon it should be cut back. I often see plants that were not cut back the previous year, and they look awful! To cut it back, you cut down past the bare stem, to the first or a lower pair of little shoots. When you are done, you want to have a rounded plant, so if any of the stems will be rather tall, you can cut deeper into them to improve the regularity of the silhouette. However, you don't want a sheared look, so it is best to cut each stem individually, so they won't be all the same length.

And then there is California poppy. It is a perennial, contrary to what most sources say. After it blooms out, and becomes a mass of brown stems with seedpods at the end, you can cut it to nearly the ground. Leave a couple of inches of stem, and look for green shoots regrowing near the ground. If you find any shoots regrowing, be sure not to damage them. As with watsonia, you have some leeway. Maybe there are still a few flowers on the plant, but it looks rather awful: go ahead and cut it back.

It is the beginning of the cutting back season. More will follow as different perennials have had their say. It is an important way to keep a garden looking fresh.


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