Perennials

Anemones are among the most beautiful flowering plants for high summer and fall gardens.  They flourish in moist, humusy soil in part sun, but perform well in average soil in full sun if kept well-watered.  Hybrids like ‘September Charm’ and ‘Pink Saucer’ are some of the more common pink Asian anemones. Or if you prefer white, ‘Honorine Jobert’ will fit the bill.  These hardy perennials flower for 6-8 weeks during the time of the year when many early summer plants are starting to look tired.  They also make excellent cut flowers!

Grape-leafed anemone – Anemone tomentosa ‘Robustissima’ is one of my all-time favorites. The foliage emerges in mid spring, forming a wide clump of fuzzy, weed-smothering, leaves. When it’s happy, the plant will spread, filling in any available space.  In early August, (before most hybrids) it sends up 3-foot tall, wiry stems topped with round buds that open into the classic pink anemone flower.

I’ve planted this one in my garden in front of a row of boxwood in the foundation planting of the house.   That area gets about a half day of direct sun, which seems to be perfect.   They are super happy with no fertilizer and only supplemental water during the dryest parts of summer.  I really enjoy the combination of Iris versicolor ‘Purple Flame’, Siberian geranium, Geranium wlassovianum, bog sage, Salvia uliginosa, and Calamintha ‘Montrose White.’

All in all, a fantastic perennial, with a very long bloom time.  Try planting a group of one type or mixing many for a more painterly look with blooms for an extended period.

When August is looming and the vibrant blooms of early summer are past, Nantucket’s gardens begin to feel the heat! The best way to guarantee splendid shows of colorful flowers late in summer, is to mix it up with annuals and perennials that bloom for a long period, or that start blooming later in the season.

Gardeners are always on the look out for perennials that flower freely. Some of the best are Geranium ‘Rozanne’, Gaura lindheimeri, Calamintha nepetoides, and Persicaria amlexicaulis. They bloom for months from the height of summer right into the fall.

Find places in the border for late summer bloomers like Rudbeckia ‘Goldsturm’, Perovskia atriplicifolia, Echinacea, Hibiscus mosc., Sedum spec. ‘Autumn Joy’, and Agastache ‘Blue Fortune’. All of these plants are hardy and will have fresh blooms in late summer.

Fill in gaps between perennials with annuals. Or design spaces for these show stoppers into your gardens. Some of our favorite annuals for mixed plantings are Verbena bonariensis and Dahlias. T

he tall, narrow stems and purple flowers of Verbena bonariensis are a great filler for areas where hollyhocks have fizzled or foxgloves have finished flowering. And the vast aray of tall and decorative dahlias can be used to add color to nearly any area of the sunny garden.

Gardeners are always looking for the perfect three season plant. Showy Stonecrop – Sedum spectabile ‘Autumn Joy’ fits the bill! It emerges from the ground in spring, looking a lot like small Brussels sprouts. As the stems lengthen, the leaves become broader and have a distinctive, succulent look. In mid summer, the flower buds begin to form, and cover the plant with open sprays of chartreuse. By September, the flowers tighten up into umbels and open to reveal tiny pink petals. As fall sets in, the color deepens to cranberry and then garnet. Even the seed heads are ornamental and look great covered with frost in front of the buff color of ornamental grasses.

Sedums don’t require much care during the growing season. If you find they get too tall and splay open in your garden, pinch then once or twice in early summer before flowers begin to form. This will force the plant to branch out and remain dense and compact.

Plant them with other late summer perennials like Perovskia, Rudbeckia, Echinacea, and Phlox. Frame the planting with Calamagrostis ‘Karl Foerster’ and you can’t lose!

 

Hemerocallis, or Daylilies have been a garden staple for years. Their stunning trumpet-shaped flowers open and senesce within 24 hours, hence their name.  The American Hemerocallis Society has over 48000 registered cultivars, and of the nearly 13000 of those are available commercially.  That makes for a huge variety in color, height, bloom season, and flower form.

Daylilies will tolerate almost any soil type, and will perform in part shade to full sun.  However, they prefer rich well drained soil.  Full sun will guarantee the most blooms, and consistent water will help keep their foliage deep green throughout the growing season.

Maintenance is simple, yet can be time consuming, if you must take care of extensive plantings.  Remove spent blossoms as they appear.  Once all the buds have bloomed, cut the entire scape (flower stalk) down to ground level.  As July turns to August, the foliage can begin to tatter and brown or many varieties.  Remove brown, dry leaves as they appear, or cut the entire plant down to six inches and fresh foliage will soon replace it.  An extra boost of fertilizer at this time will also help.

Daylilies mix very well in the border with nearly all summer flowering plants.  For a long show of color, interplant Hemerocallis ‘Hyperion’ with daffodils, then follow up with the tender perennial Verbena bonariensis.  Contrast large groups of daylilies with plants that have a different leaf form or flower color.  Echinacea looks great next to daylilies, as does Phlox paniculata and Persicaria amplexicaulis ‘Firetail’. It’s really tough to go wrong!

The American Hemerocallis Society has a superb online database.  Use it to chose plants that will bloom Early, Mid and Late season, and you can enjoy flowers all summer in a wide variety of colors and forms.  http://www.daylilies.org/DaylilyDB/

Gardening in the shade can be a challenge for gardeners of all experience levels. Luckily, plant breeders have given us a huge array of Hostas to work with!

Hostas grow best in rich loam with plenty or organic matter, but will tolerate average garden soil. To get the best out of your hostas in our lean island soil, be sure to amend the bed at planting with compost or composted cow manure. Once established, be sure to give them sufficient water and a top-dressing of organic mulch each year.

The major insect pests of Hostas are slugs and snails. They emerge at night to feed, and hide during the day. The tell-tale sign of slug and snail damage is their slimy trails left on the underside of the leaves. Effective organic controls are available and effective. Pelleted products such as Sluggo do a good job of keeping these pests at bay, while not causing the environment any harm. If you still find a lot of damage, try Hostas with leathery leaves, like ‘Krossa Regal.’

Although they prefer dappled shade, morning sun is fine for all types of Hostas on Nantucket. There are even Hostas that will perform in full sun! Those with green or chartreuse leaves tend to tolerate sun better than variegated varieties. ‘Guacamole’ and ‘Sum and Substance’ are both good choices for sunny situations, just be sure to keep them very well watered.

The form and type of leaves that Hostas display is varied. There are miniature plants that could fit in the palm of a child’s hand, all the way to giants with leaves a foot and a half wide. Some are upright, while some mound or nearly hug the ground. They can be variegated, green, chartreuse, gold or blue.

Blue Hostas are a shade garden favorite. The range in this group alone is astounding. If your garden has a shady path, the tiny leaves of ‘Blue Mouse Ears’ would look great tucked among the stepping stones. If you really want to make a statement ‘Blue Angel’ boasts leaves that are 16 inches long and 12 inches wide!

Designing with Hostas is easy. Plant the varieties that you enjoy most, then contrast them with other Hostas that have different leaf color or shape to bring interest into the composition. Liven it up with some Heuchera, Hellebores, Actea and ferns and you are on your way to a spectacular garden!

Disclaimer: I would be amiss if I didn’t mention that Hostas are deer food. Although there is a Hosta for almost every situation, they do resemble a tasty bowl of lettuce for a hungry deer. Stick with ferns and sedges, if you often have deer in the yard during the summer. Otherwise, go HOSTA WILD!

 

Professional gardeners know that creating continuous bloom in the mixed border can be challenging.  The secret to having flowers in the garden straight through until frost is incorporating Annuals, Biennials and Tender Perennials.

Annuals are those plants that grow, flower, set seed and die during a single growing season.  Some of the best annuals for the back of the border are Cosmos ‘Sensation Mix’, Cleome ‘Queen Series’ and Verbena bonariensis.  All of these plants grow quickly to more than 4′ and flower profusely into fall.  The daisy-like flowers of Cosmos do require deadheading to look their best.  If you want lower maintenance flowers, try Cleome or Verbena b.  The wiry stems and purple flowers of Verbena b. blend well with nearly everything!   TIP FOR SUCCESS:  Because annuals must complete their life cycle in one season, they tend to be heavy feeders.  Be sure to incorporate a time-release fertilizer formulated for flowering annuals into the soil when you plant them.  And don’t be afraid to follow up with a liquid fertilizer, if necessary.

Biennials are plants that form a basal rosette of leaves during the first growing season.  During the second season, they will flower, set seed and generally die.  Hollyhocks (Alcea rosea), Foxglove (Digitalis purpurea), and Lupines (Lupinus) fall into this category.  There are three ways to treat biennials.  As short-lived perennials: Cutting the flower stalk down before seeds mature, will often help the plant survive for several years.  As true biennials:  Leaving the seeds to mature on the plant and fall to the ground will normally give you enough seedlings in the spring to fill the area.  As annuals:  The best way to guarantee a great show is to replace them every year with high-quality plants.  TIP FOR SUCCESS:  Biennials tend to flower in early to mid summer.  If you don’t want a blank space in the garden when they finish flowering, be sure to plant mid-height  perennials in front that flower later in summer like Phlox (Phlox paniculata) or Turtlehead (Chelone).

Tender Perennials are marginally hardy or short-lived perennial plants.  Delphinium, Dahlias, Strawberry Foxglove (Digitalis mertonensis) and some tropicals fit into this category.  TIP FOR SUCCESS:  Marginally hardy plants like Dahlias and other tuberous plants can be dug up and stored in damp vermiculite over the winter and then replanted in early summer to avoid the possibility of freezing during winter.  During mild winters, a heavy mulch might be enough to protect some tender plants.  Some varieties are hardier than others, so experiment!

 

Most gardeners know the benefits that pruning provides trees and shrubs.  Less of us know how useful different pruning techniques can be for perennial plants.

Exceedingly tall or leggy perennials are one of the first groups of plants I think of that benefit from a quick shearing in early summer.  Eupatorium purpureum (Joe Pye Weed), for example, will grow upwards of 9′ tall, making it appear out of scale with smaller plants like Rudbeckia, Sedum, or Salvia. Cut it back by 1/3 in mid to late June to reduce the flowering height and create much fuller plants.

Another benefit of pruning perennials is delayed flowering.  Leucanthemum maximum ‘Becky’ (Shasta Daisy) is a popular plant on the island.  Shearing the plants at the front of a mass planting in late spring creates a tiered effect with taller plants flowering first at the back and shorter plants flowering later in the front.

Pruning can also be used to avoid some common issues with mounding plants.  These plants can fall open in the center as flowering peaks.  Nipponanthemum nipponicum (Montauk Daisy) is notorious for this problem.  Shear or pinch it a few times before mid-summer and you will be rewarded with a plant that holds its flowers in a compact mound.

A complete list of perennials that can be pruned in a variety of ways is available in Tracy DiSabato Aust’s book The Well Tended Perennial Garden: Planting and Pruning Techniques from Timber Press.  Tracy’s book is available at island book stores. But by all means, experiment!  If you remember a plant that tends to be leggy in your garden, it won’t hurt to pinch back a few stems and see what happens!  If you would like to enjoy your flowers a few weeks longer than last year, try shearing one plant early on to see how it reacts.

Happy Gardening!

Are you looking for a plant to cover a trellis, arbor or pergola?  Do you need something to scramble among your climbing roses or around the bare trunk of a tree?  Surfing Hydrangea Nursery offers one of the best selections of flowering and non-flowering vines on the island.  If you are interested in adding native plants to the landscape, vines can be an easy way to start; Wisteria frutescens is a late-flowering North American species that covers a pergola nicely, without being nearly as rampant as its Asian cousins; Campsis radicans (Trumpet Vine) is also a great choice for showy flowers later in the summer; Parthenocissus quincefolia (Virginia Creeper) is spectacular in the summer trained over a wall or wherever you have space!  Why not give one a try?  The wildlife will thank you!