If you grow parsley in your herb garden, some simple pruning will help keep the plant healthy while increasing its overall yield. This is important since this plant tends to be a very active grower, and if it is not occasionally thinned out, it loses its vigor. Many parsley species flower abundantly, producing a lot of seeds as they die. Removing them will conserve the energy it takes the plant to produce seeds, redirecting it to foliage production instead. Pruning will also stop your parsley from taking over the garden and choking out other plants, and it will increase air flow in the bed so that the plant doesn’t contract diseases like powdery mildew.
Tip: Always thoroughly wash your pruning shears after trimming back any plants so that you do not risk transferring diseases to otherwise healthy plants.
1. Check for Dying Blooms
Check frequently to see if your parsley plants have flowered. When these blooms begin to fade, it is important that you deadhead—or remove—them immediately; you may have also heard of this process described as "pinching back" the flowers. By deadheading or pinching back, you prevent the plant from over-seeding in the garden, which will quickly cause overgrowth of the parsley. All you do is just snip the dying flowers at the root of the stalk with a sharp pair of pruning shears and discard them.
2. Trim Unhealthy Foliage
Always keep a watchful eye out for any unhealthy foliage. Trim yellowed, brown, or insect-eaten leaf stalks at ground level and discard them. Do this any time you notice such foliage.
3. Give it a 1/3-Inch “Haircut”
Take your scissors and just give your parsley plant a trim or “haircut” to keep it from growing too high. Periodically take the tops of the plant and cut about a third of an inch off. Do this when you notice the plant is exceeding an ideal height at any time during the growing season. A trim will not damage or kill the parsley and will allow you to maintain a nice appearance in your herb garden while controlling overgrowth. This can also be done by simply plucking back the leaves.
Tip: When the time comes to begin harvesting your parsley, begin by cutting the leaf stalks to the ground, starting on the outside of the plant. As you continue to harvest, work inwards. Don't be afraid to harvest too much. Healthy parsley plants will always bounce back!
4. End with Mulching
After taking care to prune your parsley, make sure to mulch the plant to keep it protected against the cold. Take mature compost and spread it in the top soil to improve moisture, but keep it away from the roots to prevent rotting.
Parsley is a biennial herb, meaning that it will grow for two years. At the end of the second year it will send up many flower stalks (called "bolting"), go to seed, and die. When you notice the parsley begin to bolt, you should dig it up and discard it; nothing can prevent the parsley from dying after the second year of growth. Many treat this herb as an annual simply because the foliage becomes bitter as it ages. Whether you choose to treat your parsley as an annual or biennial, pruning will be a necessary part of its care.
Tip: If you want to save your parsley seeds to plant next season, do not dig up your plant when it bolts. Instead, allow the parsley to go to seed and snip off all of the seed casings. Store them in a cool, dry place during the winter. In the following spring, soak the tough seed casings in hot (but not boiling) water. Let the water cool to room temperature and leave the casings in it overnight. Pull the seeds out in the morning and sow them in your garden for a brand new parsley plant.