Sow or hog fennel is one that until recent times has not been seen growing wild in North America. But today, you can find it growing in New England. It has limited USDA Plant Hardiness Zones of 6a through 8b. While it is noted to be a perennial, in fact it is what is referred to as a monocarpic. What this term means is that a plant will continue to grow but once it flowers, the plant dies.
This plant produces beautiful blue green leaves during its vegetative stage, which can last several years. Next, the plant produces a tall flower stalk that is topped with an umbrella of yellow flowers. At this point, the flower head looks like dill. Once the yellow flowers are spent and the seeds are ripe, the plant dies with the seeds falling to the ground. This form of seed dispersal is another reason why some gardeners mistaken the plant as a perennial. Without control, the patch of hog fennel will grow in diameter.
When it comes to plant the sow fennel seed, this should be done in the fall. The environmental conditions that this plant require include a moist but well draining soil that is fertile but can really grow in any soil that drains well. The light requirement is easily met by full sun or partial shade.
Planting the seed of the sow fennel is simple and only requires one to sprinkle the seed on the soil’s surface. Do not cover the seed. Water in the seed but be careful when doing this task. The seed of this plant is small and can easily be push too deep into the soil, which will result in reduced seed germination.
While the discussion is on sow fennel, there is also giant hog’s fennel and sea hog’s fennel. Depending on the type of sow fennel you are planting will determine the seedling spacing, which can range from 9 to 24 inches.
As simple as this plant is to grow, it does have a few problems. One plant disease that is commonly found in this plant is powdery mildew. The easiest way of preventing powdery mildew is to spray the plant off in the morning. This creates an environment that powdery mildew does not like but make sure that you only do this in morning. The reason is, it give the foliage time to dry before evening.
The pests that like sow fennel include slugs, aphids, and snails. The best approach to deal with these pests is to use Mother Nature and attract beneficial insects that feed on these organisms.