Days to germination: Not necessary if grown from seedling
Days to harvest: 60 days
Light requirements: Full sun
Water requirements: Regular watering
Soil: Rich but well-drained
Container: Suitable, and necessary in most climates
Lemon verbena is a heat-loving plant from South America, and you will have to grow it indoors if you live above zone 9 and want your plants to last more than one season. But you can get a nice harvest even if you just grow your plants outdoors for one year. It’s very fast growing.
As its name probably suggests, the leaves have a bright lemon taste that makes is particularly popular in herbal tea. Some people find they can even use lemon verbena leaves as a replacement for actual lemon zest or juice. It can be used in either sweet or savory recipes with meat, fish or vegetables.
It can grow up to 15 feet in the right tropical conditions, but most gardeners find it stops growing around 4 feet. Container or indoor plants may be even smaller.
Starting from Seed
Lemon verbena is not usually started from seed, so you may have trouble locating some. You will need to get a cutting from an existing plant or purchase started seedlings.
With a cutting, you just need a small sprig of stem that includes a few leaves. Just stand it up in a small glass or jar of water until it begins to sprout roots from the cut end. Once the roots are longer than an inch, you can move your cutting into some potting soil.
You should let your cuttings take root in soil for a few weeks before transplanting directly outside. If you are growing your plants indoors anyway, you can transfer the cuttings right into their pots.
Once you have some seedlings to plant, you can put them out in the garden or into their containers for indoor growing. Outside, you should allow at least 2 feet on all sides to accommodate the large shrub that your plant will eventually become.
Loosen up the soil and add some compost before planting your seedlings. Plant them out after all frosts are finished for the year, which will be very early spring for these warmer zones.
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.
With regular pruning, you can keep your indoor lemon verbena to a reasonable size. Even so, your plants will eventually need a pot around 5 gallons in size. You can either start in a large pot, or re-pot the plant as it grows. Re-potting will give you the opportunity to trim the roots a little bit to help keep the plant small.
Water potted lemon verbena regularly, and use a diluted fertilzer once a month. If you have a larger plant, you can even apply the fertilizer every two weeks.
As mentioned above, the plant will lose its leaves in the winter. This is particularly true of container plants that are growing indoors. It can make for a rather unattractive houseplant for a while, but don’t forget to water at least once a week anyway. After the leaves have dropped, do not fertilize again until the new spring grow starts.
Pests and Diseases
Due to the strongly fragrant oils, few insects will bother your lemon verbena. The only pests you need to watch out for are whiteflies and spider mites. The whiteflies are a particular problem with the indoor plants, so don’t assume your potted lemon verbena is safe just because it is in your living room.
The usual natural insecticidal sprays can be very helpful though you will want to do your spraying right after you’ve harvested so you don’t end up picking leaves that have just been treated.
Harvest and Storage
The leaves and tender stem tips are what you want to pick from your lemon verbena plant. As a perennial shrub, the older branches will be too woody to provide any of the characteristic lemon flavor.
Harvesting can be done any time, providing you never take more than about a third of the leaves off the plant at one time. Make sure you give it time to recover before making another large harvest. You can pick leaves from lemon verbena any time, but they will have their strongest lemon flavor right before the plant goes to flower.
The best way to store lemon verbena for any length of time is to dry it. It doesn’t lose any of its taste or fragrance, and can be stored for many months once dry.