(GLAH-see-um  FLA-vum)

General Information:

I don’t normally include biennials as the Plant of the Month since they are just too much trouble to keep going in a garden, but Glaucium flavum is going to be an exception. Besides large yellow or orange flowers, the horned poppy has one of the most unusual leaves I have ever seen.

Glaucium flavum f. fulvum; photo by Robert Pavlis

The soft looking, blue-gray leaves are very unique and make a great addition to a rock garden. As a young plant it grows a rosette with leaves close to the ground, as pictured. As it gets older it becomes more upright. The plant likes a sandy, lean soil, but seems to also do well in normal garden soil.

I received my first plant as a small seedling from a friend. It didn’t grow very big, probably because it did not like being transplanted, as is the case with most poppies. It did flower, made a bit of seed, but never came back after the winter. Now, four years later, the plant in the picture showed up as a seedling from that original plant.

Glaucium flavum f. fulvum; photo by Robert Pavlis

The plant in the picture is named Glaucium flavum var. aurantiacum or Glaucidium flavum f. fulvum. It looks exactly like Glaucium flavum except that the flowers are orange and is commonly called the orange horned poppy.   

Glaucium flavum has naturalized in several states and in Ontario. In Massachusetts it is classed as an invasive and is prohibited from sale.

Life Cycle: biennial (some say it is perennial)

Height: 30 cm (1 ft)

Bloom Time: starts mid-summer and flowers until frost

Natural Range: UK, Europe and Mediteranium

Habitat: costal beeches

Synonyms:  Glaucium luteum, Glaucium glaucium, Chelidonium glaucium

Cultivation:

Light: full sun

Soil: well drained

Water: drought tolerant

USDA Hardiness Zone: 5 – 10

Propagation: seed

Seedex availability (ORG&HPS annual Seed Exchange): occasionally

 (fil-ih-PEN-dyoo-luh ul-MAR-ee-uh)

General Information:

Filipendula ulmaria, also known as meadowsweet and queen-of-the-meadow, is native to parts of Europe and Asia and has naturalized in eastern North America. It spreads readily by seed in moist areas.

The variety ‘Flore Pleno’ has larger flowers and is sterile (ie does not make seeds), making it a better selection for your garden than the species.

Filipendula ulmaria ‘Flore Pleno’; photo by Robert Pavlis

This is an attractive tall perennial with stiff stems that hold the flowers well. It’s unusual dark green, compound, pinnate foliage contrasts well with other more common foliage types in the garden. Flowers are a clear white and become a show stopper for several weeks in mid-summer.

Filipendula ulmaria ‘Flore Pleno’ prefers a moist to wet area, but grows well even dry. Mine grow under sugar maples at the edge of the drip line and are rarely watered. A wetter location will add some height to the plant and encourage it to spread faster.

Filipendula ulmaria ‘Flore Pleno’; photo by Robert Pavlis

Life Cycle: perennial

Height: 1.3M (4ft)

Bloom Time: mid to late summer

Natural Range: Europe and Asia

Habitat: moist, boggy areas in both sun and part shade

Synonyms:  none

Cultivation:

Light: full sun to part shade

Soil: neutral to alkaline

Water: average moisture to dry

USDA Hardiness Zone: 3– 7(9?)

Propagation: seed (only for species), division in spring

Seedex availability (ORG&HPS annual Seed Exchange): frequently for species, never for variety ‘Flore Pleno’

 (er-ih-THROH-nee-um a-mer-ih-KAY-num)

General Information:

Erythronium americanum is a great little plant for the spring, shade garden. It is native to most of Eastern North America and can found in many wooded areas in this region.

Nice mottled leaves with a yellow-orange tinged flower, Erythronium americanum  is commonly called yellow adder’s tongue, yellow trout lily, yellow fawn lily and yellow dog-tooth violet.  However it is not a violet.

Erythronium americanum; photo by Robert Pavlis

Corms of this plant will produce stolons that slowly spread to form large colonies. The corms can be quite deep making it difficult to transplant, but it can be grown from seed which can take 5 years to flower.

The bulbs (correctly called corms) of Erythronium americanum go deeper on their own if they are planted too shallow for the soil conditions. A lot of bulbs can do this using one of two mechanisms. Narcissus use contractile roots that grow down, get established and then pull the bulb lower. Tulips don't use contractile roots, but they do use something called ‘droppers’. A dropper is a stolon-like structure that grows down and then forms a new bulb at the tip of the dropper. Erythronium americanum use droppers, and do not have contractile roots.

By midsummer the plant goes under ground until next spring.

The main problem with this Erythronium is that it can be shy to flower and the reason for this is still unknown. In a typical colony you will find hundreds of single leaves that do not flower and only a few double leaves that do flower. I had a section of the garden that had a high percentage of flowering plants one year, and almost none the following year. So it is not just a case of maturity. Some claim that a single flowering plant will tend to divide into many smaller corms and therefore not flower the following year. This may be accelerated by a dry spring.

Some claim that extra fertilizer, more light or a very wet condition will produce more flowering plants. It could be that deeper corms flower better or that shallow corms flower better. Placing a rock under the corm at planting does not seem to work. Or it might be that some clones flower more than others. It is odd that these conditions are not better understood for a plant that is both beautiful and native to our woods.

In any event the plant makes a good addition to the garden, even if it is grown just for the leaves.

Life Cycle: perennial bulb

Height: 20 cm (8 in)

Bloom Time: spring

Natural Range: Eastern North America

Habitat: moist hummusy woods

Synonyms:  none

Cultivation:

Light: part shade to full shade

Soil: moist, well drained

Water: moist in spring, dryer in summer

USDA Hardiness Zone: 3– 9

Propagation: seed, offsets

Seedex availability (ORG&HPS annual Seed Exchange): rarely