Evergreen shrubs come in many shapes and sizes, with some bringing colors other than green to your garden. The gold thread cypress (Chamaecyparis pisifers "Filifera Aurea") is one of these colorful shrubs, with golden yellow, threadlike foliage that covers thin, graceful branchlets. Not a true cypress, it's sometimes called Japanese false cypress or golden mop. This plant has a naturally rounded, pleasing shape, but can eventually outgrow its space and crowd other plants. If you have an overgrown gold thread cypress, it's important to take the right approach to rejuvenate the plant and bring it back within bounds.
The Best Time
The gold thread cypress is called a scale-leaf evergreen because its foliage consists of flattened, threadlike needles that wrap around the thin branches like delicate scales. It's best to prune this shrub early in spring, just before new growth appears. This allows new growth to cover pruning scars quickly, avoiding the appearance of cut stubs, and also gives the plant a full season to recover from the shock of pruning. You can do additional fine-tuning of the plant's shape later, in May, June or July, while the plant is still actively growing. Avoid cutting the shrub back in late summer or fall, because tender new growth might be damaged by winter cold.
The gold thread cypress has no dormant buds that can produce new growth on older, leafless branches, like most evergreens of this type. Because of this, never cut off all branches that have foliage, because this can kill the plant. If the plant is too large overall, prune about one-third to two-thirds of its branches the first year, and repeat this during the next year or two, giving the plant time to recover and put out new stems. Cut each branch back to a strong lateral branch or shoot, choosing a length that approximates the final desired size of the shrub. Make sure all cuts are made at a point where there's still green foliage and visible buds, and prevent spread of plant disease by wiping your pruning blades with a cloth soaked in rubbing alcohol between cuts.
After you've started pruning a gold thread cypress, you may need to also make training cuts once new growth appears, to help the plant develop the desired shape. As new lateral branches form, trim back any that are overly long and thin, to promote more branching and bushiness. Help the plant fill in any open spaces by trimming shoots just ahead of a lateral bud that faces toward the open area -- new side shoots should help fill in these empty spots.
Care After Pruning
Keeping a freshly pruned plant well watered helps support healthy new growth -- during dry spells, provide supplemental water, aiming for about 1 inch per week, including rain. Mulching under the plant with a 4- to 6-inch-thick layer of straw or shredded bark also helps conserve soil moisture The gold thread cypress is frost-hardy and grows in U.S. Department of Agriculture plant hardiness zones 4 through 7, so it can encounter winter storms and snow in colder parts of its range. Clearing newly fallen snow from between tender new branches helps keep new growth in good condition, as does protecting the plant from wind damage by surrounding it with a burlap screen attached to poles hammered into the ground.