China Plant Hardiness Zone Map

China Plant Hardiness Zone Map Map by Mark P. Widrlechner, USDA-ARS North Central Regional Plant Introduction Station, Ames, Iowa. For more information, or to request a laminated hard copy of this map, please contact us at 515-294-3511 or send e-mail messages to

How to grow Astilbe

Many of the older species had colourless flowers which may be the origin of the name, from the Greek a, no, stilbe, rightness (Saxifragaceae). A small genus of herbaceous perennials with feathery plumes composed of myriads of minute flowers in white, many in shades of pink and deep crimson. They are delightful waterside plants but they will grow in the […]

Centaurea – Knapweed, Hardy Cornflower, Perennials Guide to Planting Flowers

Centaurea – Knapweed, Hardy Cornflower, Hardheads, Mountain Bluet The Centaureas are some of the most graceful flowers to grow in any garden. The flower heads are like showy, ragged thistle blooms of bright red, deep purple, golden yellow and blue. They grow from 2 feet to 3 1/2 feet tall and bloom during the Summer months. SPECIES. The Golden Knapweed […]

Arabis – Rock Cress, Wall Cress, Perennials Guide to Planting Flowers

Arabis – Rock Cress, Wall Cress The Rock Cress is a small, white, four-petaled flower and its masses of snowy bloom early in the Spring contrast beautifully with the Basket of Gold (Alyssum saxatile compactum) and the blue False Wall Cress (Aubrietia). It blooms very soon after the snow disappears and the flowers are so numerous that when a plant […]

Asphodel – King’s Spear, Perennials Guide to Planting Flowers

Asphodel – King’s Spear The classic Asphodel is rarely seen in gardens although its interesting, tall and stately spikes of yellow and white flowers are of interest to garden lovers. The Asphodels are variously cataloged as Asphodeline and Asphodelus; the former genus is erect and has leafy stems, the latter is stemless. In Asphcdeline lutea the flowers are sweet scented […]

Ajuga – Bugle Flower, Perennials Guide to Planting Flowers

Ajuga – Bugle Flower For creeping over the soil in shaded places the Bugle Flower is excellent. Two sorts are commonly cataloged. Ajuga replans rubra has deep purplish-blue flowers and purplish leaves and is prostrate in habit; A. genevensis is more upright in growth and bears flowers varying in color from dull red to white and blue. There is a […]

Using annual flowers for quick color

When you want lots of color quickly, flowers to cut by the armful and bloom all summer, you want annuals. For earliest possible bloom, sow seeds indoors, then transplant-or buy started plants in May. But you’ll still get plenty of flowers if you wait till the danger of frost is past and sow the seed of quick-growing varieties where you […]

Lythrum – Purple Loosestrife, Perennials Guide to Planting Flowers

Lythrum – Purple Loosestrife, Black Blood The common Purple Loosestrife (Lylhrum Salicaria) grows from 4 feet to 6 feet tall and blooms during the months of July and August. Banned by most States in the United States. The foliage is willow-like and the tall, erect, graceful spikes produce brightly colored reddish-purple flowers. The Rose Loosestrife (L. roseum superbum) has a rose-colored […]