Top 100: Clumping Herbs (Skirret)

This is the sixth of a series of posts that will cover the "Top 100" forest garden plants taken from volume 1 of the Edible Forest Gardens books. In this post we begin our list of clumping herbs.

Skirret — Sium sisarum
Hardiness zone 5-9, full sun to part shade, clumping, 3 ft. x 1-2 ft., edible roots, specialist nectary (image above)

Skirret is a productive root crop and specialist nec­tary plant for the sunnier parts of the forest garden. Its roots have long been cultivated in Eurasia but fell out of favour in the twentieth century. This is probably because the pencil- to finger-thick tap­roots, which grow as a dense cluster, often have a fibrous or woody core, at least in unnamed varieties. Fortunately, improved varieties that entirely lack this trait are now available and can be vegetatively propagated. The cooked roots are sweet and filling, like a blend of parsnip and potato. This productive and low-maintenance vegetable may enjoy a renais­sance as we come to appreciate the role of multi­purpose perennials in forest gardens and other edible landscaping systems.

Sweet Goldenrod - Solidago odora
Hardiness zone 3, full sun to part shade, clumping, 2-4 ft. x 2-4 ft., edible tea, specialist nectary

Goldenrods are ubiquitous species in the oldfield stage of succession throughout the eastern forest region. As a group, goldenrods are important for beneficial insects as a fall nectar source and a place to aggregate and then spread into the garden. Sweet goldenrod has the added benefit of being one of our finest native tea plants. Blue mountain tea, a beverage made from the leaves and flowers, has a licorice-like flavor. The leaves also make a nice nibble. As goldenrods go, this species is not very aggressive, mostly staying in place as a clump. A few sweet goldenrods in the sunnier phases or areas of your garden will provide many benefits with little care.

Comfreys (Symphytum spp.)

Large-flowered Comfrey - Symphytum grandiflorum
Hardiness zone 4, full sun to part shade, clumping, 8-12 in. x 18 in., dynamic accumulator, ground cover, beneficial habitat

Russian Comfrey - Symphytum x uplandicum
Hardiness zone 6, full sun to part shade, clumping, 1-4 ft. x 3 ft., dynamic accumulator, beneficial habitat (image below)

Comfreys are fantastic functional plants for the forest garden. They are perhaps the best of all the dynamic accumulators. They grow extremely well in most conditions, and you can cut them for nutrient-rich mulch several times each season. They also excel at attracting beneficial insects, pro­viding a preferred egg-laying and overwintering site for many species. Comfreys are also beloved by spiders, hosting as many as 240 per square meter in the soil below them during winter, according to one study. The challenge is that comfreys are incredibly persistent—once planted, they are virtually impos­sible to eliminate. A tiny root piece left in the ground will start a new plant. In addition, the species most commonly grown spreads by seed. Comfrey has taken over many gardens—don't let it happen to you!

One way to avoid this is to plant Russian com­frey, a sterile hybrid of two species, meaning it cannot make viable seed and, thus, cannot be weedy by seed. It is just as persistent as the common species, however. Large-flowered comfrey is a ground-covering species that forms a low mound. It will spread vegetatively and to a certain degree by seed. Large-flowered comfrey is a fantastic soil-building ground cover for partial shade.