How to Grow Lemon Verbena | Backyard Gardening Blog
Once your plant get to 6 inches or more in height, cut back the top by about 2 inches to force the plant to make more side branches. A bushy plant will give you more leaves to harvest than a tall skinny one.
Lemon Verbena needs lots of water, so you will want to water your plants at least twice a week. The soil should never really dry out. A feeding of standard fertilizer can be applied twice a year, in the spring and fall to maximize growth.
After a few years of growth, your bush can develop some dead or overly woody branches. It’s fine to prune them out, and that will encourage the plant to sprout more new leaves.
If you really want to keep your plant compact, you can give it a vigorous pruning each winter. When the plant is dormant, you can cut it back to a height of 14 to 18 inches. It won’t harm the plant, providing you do this each winter. Once it grows 3 or 4 feet tall, this kind of pruning can kill the plant.
Around mid-summer, your plant will blossom small pale flowers that have the same lemony smell as the leaves. You can actually use the flowers as an herb, just like the leaves. Unlike other herbs that need to be harvested before the flowers come out, there is no problem with lemon verbena. Just enjoy the blossoms and keep picking leaves.
One quirk about lemon verbena is that it will lose its leaves in the winter, due to the shorter day length. This will happen even if you keep your plants indoors (unless you use grow lights). It doesn’t mean there is anything wrong with your plants.
When it drops its leaves, just leave it be. Water it around once a week until the longer spring daylight hours prompt it to come back to life on its own.
Basic Potting Soil
2 parts coir or peat
2 parts sieved compost
1 part course sand (builder’s. Make sure it is free of herbicides), grit, and/or perlite
1 part vermiculite (optional, but I like it for water absorption)