Perennials

A favorite of homeowners and landscapers alike, Nepeta x faassenii and its cultivars is a stellar plant for Nantucket. It forms a mound of pretty grey-green foliage early in the season, and is covered in blue flowers for well over a month in early summer. Cut it back in July, and you can expect the same show all over again before Labor Day.

Nepeta prefers full sun and well drained soil. It is extremely deer resistant and tolerant of salt, wind and drought. One island landscaper has taken to calling it the ‘The Welcome Plant’ since it is so friendly and easy care. There is a cultivar for nearly every situation. As long as you have at least a half day of sun, and some drainage, this plant will perform for you.

Common cultivars and their attributes are listed below:

•   ‘Six Hills Giant’: At 3′ tall x 3 or more feet wide, this is the largest plant in this group. Great for covering a large area in a hurry. If not planted in full sun, this one can get floppy and splay open. Try shearing it back early in the season, to keep the plant stocky.
•   ‘Walkers Low’: Don’t let its name confuse you, this is not a dwarf plant. It is named for a garden in England, were it was selected. 2007 Perennial Plant of the Year! 3′ wide and tall. Somewhat more compact than ‘Six Hills Giant’
•   ‘Dropmore’: This one is considerably smaller than those listed above at 1.5′ tall and wide. A good option for smaller spots.
•   ‘Blue Wonder’: Another good variety for smaller spaces. In my experience, ‘Blue Wonder’ is just slightly smaller than ‘Dropmore’, but the foliage is flatter and somewhat less grey.
•  ‘Snowflake’: A small variety with clear white flowers. We don’t always stock it, but if your plan calls for white, try this cultivar. Not growing more than 15″ wide, it’s a good option for along a pathway, or a small white garden.
•  ‘KitKat’: A true dwarf plant. This little one only grows to a foot or more tall and wide. Great to tuck in at the edge of the border.

Many gardeners realize the benefits of pruning woody plants and trees. But perennials can really benefit from some pruning too! Montauk Daisies, Nipponanthemum nipponicum,  have a tendency to get huge and splay open late in the season, just as they come into flower. It’s nearly impossible to stake them or tie them and still make them look natural.

The solution to this problem is a little shearing early in the season. In May, cut back the growth by at least a third. Have no fear! They will rebound quickly, and the result will be a dense plant with shorter stems, capable of holding the flowers upright in Autumn. If you want a much smaller plant than previous seasons, consider one more pinching in June, before flower buds are set.

When most gardeners think of vines, they picture them growing on tuteurs and trellises. But there is no need to pull out your hammer and nails every time you bring home a vine to plant!

There are plenty of vines that happily scramble along the ground, filling gaps and smothering weeds. Many of these will produce far more flowers grown horizontally. Clematis are a perfect example of this. Plant them at the front of the border and train them along areas often reserved for bedding plants, and they will reward you with a long show of flowers. Or let them flow around your shrubs, in waves of color. A Sweet Autumn Clematis in full flower is much like a wave cresting in the garden!

Vines can be a great solution to filling in shady areas, too. English ivy makes a fantastic green groundcover for deep shade. Why not use a Climbing Hydrangea along the ground? We’ve planted it below our welcome sign at the entry to the nursery. H. anomala petiolaris var. tilifolia has much smaller leaves than the species and will tightly hug the ground. Other options to consider are Schizophragma hydrangeoides, Akebia quinata or the ever popular Vinca minor.

We have a wide selection of vines in stock, why not consider one the next time you need to cover the ground in a hurry?

The humid days of August can take their toll on the most avid of gardeners. A lot of maintenance tasks become overly routine -deadhead, weed, water, mow — REPEAT. But as September rolls around, there seems to be a surge in enthusiasm for many of us. We want to get out there and do something. Something big! If you’re feeling frisky, dividing might be just the chore for you!

Daylilies are a pleasure to divide. First, cut back the foliage to a few inches. Then press a perennial fork into the ground a half a foot or so from the edge of the clump. Work your way around, pulling back on the fork to tease the plant out of the ground. If the clump is very large, feel free to dig it up in sections. Once you have it out of the ground, you can simply pull apart the clump into divisions with 2 or three growing points.

Divisions are easily planted. Just poke them into loose soil!

Anemones are among the most beautiful flowering plants for fall. They flourish in moist, humusy soil in part sun. If you must add them to your sunny border, be sure to keep them well watered.

‘September Charm’ and ‘Pink Saucer’ are some of the more common pink Japanese anemones. Or if you need a dainty white, ‘Honorine Jobert’ will fit the bill.

Grape leafed anemone –Anemone tomentosa ‘Robustissima’ is one of my favorites. The foliage emerges in mid spring, and forms a wide clump of fuzzy leaves. In late summer, it sends up 3 foot tall, wiry stems topped with round buds that open into the classic pink anemone flower.

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!