The fennel plant is a perennial in the Apiaceae family, so it’s related to parsley, dill, and coriander. It’s native to the Mediterranean, and was as popular medicinally among the Ancient Egyptians and Chinese as it is today. Its light liquorice flavor makes it treasured by home cooks and professional chefs alike. Read on to learn how to grow your own!
Varieties of Fennel
There are 2 types of fennel plant; common fennel and Florence fennel.
This large, branching plant can reach over 5ft in height, and its clusters of yellow flowers attract butterflies throughout the summer months. This makes it an attractive addition to any pollinator garden. You can harvest both the seeds and leaves for culinary purposes, and it’s hardy in US hardiness zones 4-9.
Bronze fennel is a hardy variety of common fennel. It’s also known as “smokey”, and produces purple-bronze foliage, making it an attractive garden plant.
This cultivar is smaller than common fennel, reaching no more than 3ft in height. It produces a large, bulbous leaf stalk which can be harvested and eaten raw or cooked. Consequently, it’s also known as bulb fennel.
Florence’s leaf stalks are similar in texture to celery roots, with a sweet licorice flavor. The plant’s feathery leaves are also edible, like common fennel.
The Trieste cultivar produces attractive copper-bronze flowers. Other reliable varieties include Rondo F1 and Orion, while “Zefa Fino” is a quick-growing variety, ready to harvest in 65 days.
This fennel is hardy in USDA zones 5-9.
Fennel is perennial in USDA zones 6 and higher. In zones 2-6, sow quick-growing varieties as annuals. These mature within 65 days, negating the possibility of bolting.
How to Sow Fennel Seeds
You can easily grow fennel plant from seed by sowing directly into the soil or a container. The best time to sow fennel is in early to mid spring. You can also sow in mid summer for a fall harvest. Germination requires a temperature of around 68℉.
The fennel plant prefers an acidic, well-draining soil. However, it grows just as well in neutral and slightly alkaline environments. Due to its tall growth habit, fennel works best at the back of a bed.
This herb does best in a sunny location. Prepare the soil by weeding it and raking it, breaking up any clumps that could disrupt the root system.
Soak the seeds for a day before planting to encourage germination, then sow seeds half an inch deep. Sowing three or four seeds every 10-12 inches allows for some seeds to fail. If all the seeds germinate, thin out the weaker seedlings, leaving only the strongest to grow on.
You can also start seeds in module trays with fresh general purpose compost. However you’ll have to be very careful when transplanting as the fennel plant hates root disturbance. Transplant seeds 4 weeks after germination.
Caring for Fennel Seedlings
After sowing, gently water the area with a fine spray. Punching a couple of small holes in a plastic bottle cap is a quick and easy way to make a seedling spray. The water from this will be more gentle, and less likely to wash seeds away than the heavier spray produced by a watering can. Keep the soil moist until the seedlings have germinated and are establishing themselves.
If you’re growing bulb or Florence fennel, you’ll notice that the stem base swells as the plant grows. When swelling begins, earth up the plant as you would when growing potatoes. If you’ve never earthed up a plant, it’s simply the process of pushing loose soil up against the plant’s base. You can also add fresh soil or mulch to the base.
Earthing up helps to support the plant as it grows, preventing it from bending and snapping in the wind. It also helps to produce paler, more tender bulbs.
Caring for Your Fennel Plant
This is a largely low-maintenance plant. However there are a few things you can do to ensure a successful and healthy fennel plant.
Watering and Feeding
When it comes to watering fennel plants it’s better to under-water than over-water. Under-watering encourages roots to spread through the soil looking for moisture. This leads to the plant forming a better, healthier root system.
Don’t let the soil dry out completely, as dry soil can form a hard crust, making it hard for water to penetrate the soil. As a general rule, water the plant every 2 days. During hot spells you may need to water as often as twice a day.
If you wish, you can apply a mild dose of liquid, organic, general purpose fertilizer every 3 weeks. However this isn’t necessary. To give the fennel plant an extra boost, apply a biodegradable mulch such as glass clippings to the soil around the base.
Remove dead stems at the end of the growing season. If your fennel plant is a perennial ,this will help it to re-emerge next year. Additionally, cutting back fennel early in the second season will encourage bushier growth.
Deadheading is necessary for seed harvest, and also prevents over seeding. While fennel plant is not invasive its ability to re-seed means that it can take over spaces if not regularly maintained.
Fennel plants can be divided but this is difficult to achieve successfully. Like other members of the Apiaceae family, fennel has a long taproot that dislikes being divided or moved.
It’s easier to propagate the plant by seed instead. Just sow seeds the following spring, as the soil starts to warm.
Common Fennel Plant Problems and how to Solve Them
The most common threat to fennel plants comes in the form of slugs and snails. These can be particularly problematic when seedlings are young. Organic slug pellets or beer traps are great natural methods for protecting young plants. If you’re growing the plants in containers, a copper strip around the pot will prevent slugs and snails from accessing the pot.
Greenfly colonies can target fennel plant tips or leaves. These pests suck the sap from the plant, encouraging the growth of a black sooty mould. Wash away infestations with a hose pipe or a mixture of a small amount of liquid dishwashing soap mixed into water.
Carrot root fly
This is unlikely to target your fennel plants, unless carrot root fly is a major problem in the garden.
Keeping the roots wet, not waterlogged, will discourage bolting. In warm periods you may need to water twice a day, and grass clipping mulch will help the soil to retain moisture. Netting or shading with taller plants can also help to alleviate heat-instigated bolting.
Gardeners in warmer climates can try growing bolt resistant varieties such as Victoria or Cantino. If your fennel plant does bolt, don’t dig it up. The plant’s attractive yellow flowers will attract scores of beneficial insects such as pollinators and pest predators.
Fennel as a Companion Plant
As we’ve already noted, the fennel plant happily attracts scores of pollinators and beneficial insects to your garden, particularly when it flowers.
That said, fennel is a poor companion plant because of its strong scent. While it will grow in flower and herb beds, other plants can struggle around it. For this reason many people chose to grow fennel in an isolated location or in a container on its own.
Planting near dill is a particularly bad idea. This is because cross pollination can cause both plants to develop strangely flavored seeds.
Interestingly, one of the few plants that doesn’t seem to be affected by fennel’s presence is mint.
Harvest fennel leaves as required during the spring and fall as desired. To harvest leaves, snip off tender young leaves with a clean, sharp scissors.
Use the seeds fresh, or dry and store them for winter use. Wait until the seed heads turn brown before harvesting., and store seeds in a cool, dry location. The easiest way to harvest the seeds is to tie a small bag over the seed head. Leave it in place for a few days before gently shaking upside-down, which releases the seeds into the bags.
Pull fennel bulbs when they reach 3 inches in diameter. Furthermore, pulling every other bulb gives those left in the ground more room to grow. Don’t let the bulbs become too large or they lose their flavor, becoming tough and stringy.
To harvest the bulb, cut the stalks and leaves down to about 1 inch above the ground. Thesecan be used in salads or as side dishes. Clear the soil away from the base of the bulb, being careful not to damage it.
Gently lift the bulb with your hand. With your other hand, use a sharp knife to cut the roots beneath, and then raise the bulb out of the soil. Wash off the soil and use it as quickly as possible, while the flavor is most potent. Store these bulbs in an airtight plastic bag in a refrigerator for no more than a week.
The fennel plant is surprisingly hardy. It doesn’t need to be pulled in anticipation of the first frosts, some varieties will even survive a bit of light snow. This is a bonus because fennel doesn’t keep well, particularly when the leaves are still attached. The leaves will suck the moisture from the bulb, causing it to soften.