Erythronium or dogtooth violets are from the temperate regions of the northern hemisphere. There are between 24 and 30 species of Erythronium. They are predominantly woodland species but many get up into the sub alpine and even alpine areas of Eurasia and Western North America. The common name comes from the shape of the bulb which is reminiscent of a canine fang. Most species are to be found in North America. Like Trillium they can be split into two distinct groups, the Eurasian sp or group of species centred on E. dens-canis. (E. japonicum, sibiricum, dens-canis & caucasicum) and the North American species. The North American species can also be divided into two groups. There is no overlap geographically, they appear not to be closely related. In Eastern North America There are 5 species in Eastern North America and 18 species in the West, the great majority of these
occurring in Oregon and California.
They are spring flowering bulbous perennials emerging from February to April; flowering, setting seed and dying down in June. They belong to the group of plants that are very active before the deciduous trees have leafed out. It is important to understand that growth reserves and flowers are laid down the year previous to flowering, so the longer you can keep a plant in leaf the greater the increase in leaf and flowers stems will be the following
year. In nature they grow with many other commonly grown woodland plants such as Hepatica, Trillium & Uvularia.
How to buy Erythronium
Even though erythroniums are bulbs they don’t like being dried out. Many species have long and thin bulbs that break and damage easily. They don’t take mechanical harvesting and need careful handling. The best way to purchase plants is as a living specimen grown in a pot, they also can be purchased damp packed freshly lifted in Summer from reputable suppliers. They are raised from seed and can take five years to flower. Consequently many are not commonly available and tend to cost between £3 and £5 each.
Easily Grown Species
The easiest grown species and those which should start any collection are the following.
Erythronium californicum AGM A tall easily grown species with white flowers and a yellow centre, It and its cultivated form ‘White Beauty’ AGM, are classic garden plants.
Erythronium dens-canis AGM This European species in one of the first to flower and is reliable. One is better getting the species itself rather than some of the Dutch forms which multiply into many small bulbs which don’t flower. E. d-c ‘Snowflake’ is a fine white flowered form. All to around 15 cm tall.
Erythronium oregonum Another white flowered species often with very heavily mottled leaves. The form E. oregonum ‘Sulphur’ has palest lemon yellow flowers and is very lovely.
Erythronium revolutum AGM A classic tall growing (30cm tall) pink flowered dog tooth violet. The colour in this species varies and it is worth getting a strongly coloured and vigorous form such as ‘Knightshayes’ Pink’.
Erythronium ‘Pagoda’AGM A vigorous hybrid which is easily grown and very available, with lemon yellow flowers over bronzed foliage. Not very choice due to the large leaf growth but the best for trouble free growing.
Where to grow Erythronium
Erythronium grow best under deciduous trees in a deep loamy soil that dries out in Summer. Similar conditions to growing snowdrops etc. As few of us can hope to have ideal conditions a good aim would to have good fertile soil in shade (not coniferous), apple trees are excellent shade providers. Erythronium don’t on the whole worry about pH. A possible problem with thin chalky soils is the droughty nature of them, heavy clay soils will need draining or a raised bed for erythroniums to thrive. Raised beds can be created using peat blocks, logs, rocks or new sleepers and make ideal conditions. They also make it possible to raise these extraordinarily beautiful plants up to view their flowers more closely. They can be naturalised in thin turf and large beds around Rhododendrons or on banks.
Many of the more vigorous species will multiply vegetatively and the longer they are kept in leaf the quicker they will make up. Similarly stopping them from seeding will also increase the multiplication rate, remove flowers as soon as they are over. Seed is usually set in good amounts and can be collected once the capsule atop the stiff flower scape splits. It is best to dry the seed off slightly and sow in the Autumn. August is best. Use a 50/50 John Innes/ multipurpose compost and fill a deep container or pot. Sow the seeds and cover with coarse grit. Put outside to expose the seeds to cold and wet. In Spring a single cotyledon will come up, followed by a small single leaf in the second year. Repot in August of the second year. Feed monthly when growing. You can normally expect flowering in three to five years. The key as always is to keep the seedlings in leaf for as long as possible to maximise growth.
Pests and Diseases
They are remarkably trouble free and easily grown. The major problems are to do with poorly draining soils leading to rotting or purchasing damaged bruised bulbs also leading to rots.
Erythronium associate well with an number of plants and bulbs, they fit in naturally with Trilliums, Galanthus, Hepatica, Helleborus, Hosta, Pulmonaria, Cyclamen coum and C. hederifolium. Ideally they like a soil which will dry out in Summer although many will do very well in a normal shady bed or border