In Bloom This Week in NYC

(Achillea 'Moonshine' outside of a school building on the Lower East Side)
Yarrow (Achillea millefolium and hybrids) has proven to be an excellent perennial for urban settings. A stiff, well-branched, upright perennial, yarrow grows between 2' and 3' tall and produces striking "flat-topped" blossoms mid-summer. The flowers dry well and can be left on the stalks, which aside from ornamentation promotes the plant to self sow. There are lots of hybrid yarrow on the market so you can find them in a wide array of hot colors. Hardy from zone 3 to zone 9. Flowers best in full sun with moist soil, though I have seen the plant hold up well in dryer conditions.
Coreopsis verticillata and hybrids, or threadleaf tickseed, is a perennial I have come to love so I was thrilled to find this in a community garden on the Lower East Side.
The foliage of threadleaf tickseed is very fine, like that of the annual Cosmos. The flower is yellow however, and depending on the cultivar, can be rich and intense or light and lemony. A North American native of dry woods and open plains, this perennial does best in full sun. Even though it requires supplemental water to get established, Coreopsis can tolerate some drought over time. Deadheading the first flush of flowers can be laborious but for many varieties it will promote a second bloom in fall. This plant is comfortably hardy from zone 4 to zone 8, and grows to a nice mounded 12"-18" tall. I once planted this amidst a hillside of fragrant sumac (Rhus aromatica) in the country and the contrast of texture (the fine Coreopsis with the medium-coarse Rhus) and the burst of yellow color throughout I thought to be a fabulous combination.
Oakleaf hydrangea, or Hydrangea quercifolia, is not typically what most people think of or picture in their mind when they think of hydrangeas.

However, oakleaf hydrangeas are certainly a plant people in the city should know. Cinnamon colored exfoliating bark produces these large pinnately lobed leaves that are easily as big as your hands. Mid- to late-summer flowers are equally large and white in color, maturing pink. Another wonderful characteristic about this hydrangea is that it tolerates shade better than other hydrangeas. This native woody shrub can grow to 6' tall and wide and prefers moist organic soil. Cold hardy from Zone 5 to Zone 9. Not to mention, wait until fall and the red and bronze fall foliage will be sure to impress you.
You can see around town the hostas (Hosta sp. and hybrids) in bloom. Hosta are certainly reliable and durable plants for the New York area, both in the city and the country. Tolerant of deep shade to full sun, these mounding perennials are typically grown more for their foliage which can be large or small, green or blue or variegated, and any combination thereof. Hardy from Zone 3 or 4 to Zone 8 or 9, hostas fill in garden spaces quickly and can easily be divided in fall or spring to go even further. One interesting note that many may not be familiar with is that there are now a number of fragrant hostas available in the trade. Fragrant cultivars often have "sweet" or "honey" or "fragrant" in their names and are available at your local garden center. I used to not be so thrilled about these late summer spikes of flowers, but the fragrant ones I find to be a nice surprise.
Echinacea purpurea, or purple coneflower, is a North American native that loves full sun. With all the talk about bee populations diminishing throughout the city I love to see this plant because it does attract them quite readily. From Central Park to Thompson Square Park I have seen coneflower grown in a number of different settings. When planted in rich organic soil this perennial can grow to 3' or 4' easily and produces a plethora of ornamental purple daisy-like flowers from summer into fall. Coneflower can tolerate dry soils, but this picture taken on the water's edge in Central Park shows that they can be perfectly happy in moist conditions as well.
Here you can see why Cotinus gets it's common name, smoketree. Atop this upright woody shrub or small tree in mid-summer are produced light, airy plumes of flowers, thought to resemble clouds of smoke. Cotinus obovatus, or American smoketree, can grow upright 20' to 30' while Cotinus coggygria, or smokebush, is more of a shrub form reaching 15' tall and wide at full maturity. Either way the straight species of these woody plants has rounded or slightly obovate leaves with an attractive bluish-green color. Newer cultivars have been bred to produce red foliage and flowers and those you may see more readily in the landscape. Plant and prune many of them to add interesting structure to your garden or enjoy one as a specimen. Plant in full sun to part shade, moist to dry soil, Zones 5 to 8.
If you are driving around the country as I was last weekend then you cannot help but see all the common daylillies (Hemerocallis fulva) in bloom in gardens and roadside ditches alike. Hemerocallis has become one of the most extensively bred perennials over the last 50 years and today the color and flower variations are endless and amazing. Hardy from Zone 3 to Zone 10, the only thing you really need to know is that daylillies need full sun and well-drained soil. As the name suggests, the individual flowers only last for a day, but established clumps can get to be quite large and produce many waves of flowers. Once established these modern varieties can be quite drought tolerant. Most daylillies you will find grow to 12" or 18" but some have been bred for height and can surpass three feet or more. While the New York Botanical Garden has the largest display of Hemerocallis cultivars locally, I was presently surprised at the plantings and variation I found walking around Union Square Park.