Forsythia_DBG_2764Just when you don’t think you can stand another minute of bare branches or dead, brown-gray foliage, spring heralds its arrival in a burst of dazzling yellow. All over town, forsythias reassure us that the growing season has finally arrived.

Originally from eastern Asia, where they have been cultivated for centuries, forsythias were collected for western gardens in the early 1800s. Most current garden varieties are hybrids of two species, Forsythia suspensa and F. viridissima. The problem is that the resulting cultivars aren’t reliably hardy in much of Colorado.

Happily plant breeders have been hard at work. ‘Northern Gold’ and ‘Northern Sun’ are both the product of a cross that includes a very hardy (but not very showy) Korean species. The resulting bushes retain the spectacular floral display of their other parentage, and survive down to USDA zone 4, or even 3 with a thick mulch or good snow cover. That’s plenty of hardiness for the Front Range. ‘Meadowlark’ is another cultivar hardy to zone 4.


What plant thrives indoors, shrugs off low humidity, and blooms all winter in bold shades of white to pink to red? Surprise! It’s wax begonias!

Also called fibrous begonias, these familiar bedding plants have large, round succulent leaves in either lime green or a beautiful burgundy- or bronze-red. Flowers have fleshy petals surrounding a bright yellow cluster of stamens. Plants grow to a height of about six to twelve inches. They tend to flop, creating a solid mass of color, and even trailing over walls and container edges.

Wax begonias are usually considered summer annuals. It’s true that they do well in our gardens, given light shade or (preferably filtered) sun. Space them a foot apart in soil high in organic matter and keep the roots evenly moist. Happily, pests are usually not a problem—even the deer tend to leave them alone! (more…)

With giant, trumpet-shaped flowers facing outward around a central stalk, a blooming amaryllis makes an eye-catching houseplant. Colors range from white through pink to red (and even almost black), as well as salmon-orange. Stripes or contracting edges are common. “African” amaryllis have more compact forms suited to indoor cultivation. Dwarf amaryllis are smaller in size but can produce more blooms.

Not surprisingly, these striking, easy-to-grow bulbs are popular holiday gifts; perhaps you received one this year. There’s even a bright red variety named “Merry Christmas”!


Symphyotrichum novae-angliae (aka Aster novae-angliae)

Bright purple daisies with contrasting golden yellow centers adorn these shrubby perennials from August until October. Growing to four feet high and wide, the plants tend to sprawl unless staked. Stems bear long, lance-shaped leaves of dull green. Numerous cultivars have been developed with a wider range of flower colors, including pinks, fuchsia, and lavender.

As their name implies, New England asters are native to damp thickets and meadows of the northeast. They do well in Colorado as long as they have amended soil and regular irrigation. Don’t keep the ground soggy, however, as that encourages infection by fungal diseases. Plant purchased seedlings or rooted cuttings in full sun. Larger areas may be direct seeded in fall; cold winter temperatures are necessary for germination to occur. Pinch back stems early in the season to promote branching, but stop when buds begin to form in mid-summer.

Landscape Use
Their medium height and less-than-ideal foliage makes New England asters perfect for the middle of a perennial border. Try pairing them with other late bloomers with similar watering requirements. Tall sunflowers (both annuals and perennials) make a lovely backdrop, while goldenrod contrasts in color and form. Combining purple asters with ornamental grasses in copper and russet tones is especially pleasing.

Article and photo by Leslie Holzmann, Colorado Master Gardener.