Garden Notes

Garden Notes

The Many Shades of Potentilla fruticosa

Potentilla is another deer-resistant plant to add to your arsenal.  These small to medium sized shrubs have been popular for years, and for good reason.  Their compact habit and gently arching branches work well in mixed shrub borders, foundation beds and mass plantings.  Planted in full sun, they are super-low maintenance, tolerate many types of soil and boast flowers from June to frost.

There are more and more cultivars to chose from, but below are some of the most common.

Potentilla


Rosa rugosa 101

Rosa rugosa-1
Rosa rugosa flower

The common name of this popular plant is Salt Spray Rose. The Latin name refers to its wrinkled leaves. Growing wild in the dunes, in commercial landscapes and in home gardens, it would be difficult to visit Nantucket without seeing at least one! They are so widely visible on the island that some have presumed them a native species. In fact, they naturally grow in the sandy coast land areas of Japan, Northern China and Korea. They were introduced to North America from Asia as early as the 1700’s, but more likely in the 1840’s.

These shrubs can be used for a variety of landscape applications. They make a great short hedge, as can be seen along Baxter Road in ‘Sconset. Their tendancy to form colonies lends them very well to mass plantings. They look great in the distance, at a boundary, or up close in a driveway circle. And, as one might imagine, they can do a great job of stabilizing sandy slopes, while tolerating salt spray and wind extremely well. Like other roses, they prefer full sun, and well drained, sandy soils, with some organic matter.

Although Rosa rugosa thrives on neglect in the dunes along our shores, they require some maintenance to look their best in a more structured setting. Pruning is best done when the plants are fully dormant and the leaves have fallen. If you have many to prune, invest in a heavy set of leather gloves. Their tiny spines are notoriously irritating to landscapers and home gardeners alike. To maintain a dense, mounded shape, cut the entire plant to knee-height. This is easily accomplished with hedge trimmers or with loppers and hand pruners. Remove any obviously dead canes at ground level.  Wayward suckers can be lopped off, right next to the mother plant. Rosa rugosa hedges should be left to reach their natural height, by only removing dead branches and giving them a light shaping. During summer, lightly nip any stems that grow toward the lawn.

There is no need to deadhead Rosa rugosa — the edible hips that form just below the spent flowers bring their season of interest well into fall, and provide food for wildlife.

Rosa rugosa is free of most porblems associated with other roses, but there are some pests that use them as a food source. Deer will eat them, especially during their spring flush of growth. Deer sprays are a help to keep the damage to a minimum during the summer.  And a good fence during the shoulder season might be necessary in areas where deer are especially troublesome. Japanese beetles will congregate on Roses off all types and can completely defoliate plants in a matter of days.  Hand-pick and destroy the beetles in the morning or spray them directly with a Spinosad product.

Rosa rugosa is certainly one of Nantucket’s most popular plants. Why not use them in your next project, or try a few in your garden? We offer an ever-changing selection of cultivars and hybrids, from the common to the more uncommon. We would be happy to help you select a variety that suits your taste!


Weigela ‘Wine and Roses’

Weigela florida ‘Alexandra’ sold as ‘Wine and Roses’ under the Proven Winners line of plants is in full bloom here at the Nursery.  If you like drama in the garden, this is the plant for you! The striking combination of rosy pink flowers and deep wine-colored foliage is a great addition to the shrub border or in a large pot.  This Weigela blooms heavily in early summer and will rebloom throughout the summer. 

Deer and drought resistant, with no pest problems to speak of, Weigela ‘Wine and Roses’ is a very low maintenance shrub that packs a punch!

Weigela florida 'Wine and Roses'


Made in the Shade

Hosta 'Golden Tiara'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!

 


Tall Fillers for the Border

Digitalis purpurea 'Camelot Lavender'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!

 


Spring Flowering Shrubs

Viburnum 'Summer Snowflake'
Viburnum ‘Summer Snowflake’

Today it feels like Spring has really set in on Nantucket!  ‘Kwanzan’ cherry trees are in full bloom accross the island, giving everyone the feeling that Summer is also right around the corner!  It’s exciting to see perennials and annuals filling up the courtyard, but if your landscape still needs a few more “Bones” it is prime time for planting Spring flowering shrubs.
Early Spring shrubs like Hamamelis vernalis (Witch hazel), Pieris japonica & floribunda (Andromeda), Mahonia aquifolium (Oregon Grape), Spiraea ‘Ogon’ and Forsythia are now giving way to mid spring and early summer bloomers.  The next wave of color will come from Kerria japonica, Prunus maritima (Beach Plum), Azaleas, Rhododendrons and Viburnums like V. x carlcephalum and V. carlesii .
The final days of spring are ushered out with Lilacs.  Syringa vulgaris, the common lilac has stunning flowers with unmatched fragrance.  But don’t discount the smaller-flowered varieties.  Syringa patula ‘Miss Kim’ is an excellent landscape plant for Nantucket, resistant to powdery mildew and tolerant of more extreme conditions than others.


Perennial Pruning

Kalimeris and Salvia
Kalimeris and Salvia

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!


Ornamental Grasses

Pennisetum alopecuroides 'Hameln' flowers
Pennisetum alopecuroides ‘Hameln’ flowers

What would a Nantucket garden be without one ornamental grass or other?  From Pennisetum ‘Little Bunny’, to Miscanthus sin. ‘Gracillimus’, there is a grass for nearly everyone and their landscape.  These tough plants are not troubled by pests, diseases, rabbits or deer, and many display showy plumes or vibrant foliage later in the season.

During the first few years after planting, the only maintenance most grasses need is a hair-cut in spring to take off the previous season’s growth.  Over a period of years, the larger grasses can decline, and may need division.  Spring is the best time to divide warm season grasses like Miscanthus, taking advantage of the increased root growth that takes place as the plants break dormancy.  Spring is also the best time to install new plantings of these grasses.   We have a varied selection of ornamental and native grasses already at the nursery, and will continue to bring in more as the season progresses.


Spring Vegetables

Lettuce 'Red Salad Bowl'
Lettuce ‘Red Salad Bowl’

There are many vegetables that can be grown and harvested this time of year.  Leafy greens like Spinach and Lettuce are both beautiful and delicious.  Cole crops like Broccoli, Cauliflower, Cabbage, Brussels sprouts and Chard are extremely satisfying to grow, as they mature quickly

 


Spring Flowering Trees!

The nursery is filled with color as trees burst into flower. There is a wide variety to chose from, but the hues of pink and white predominate this time of year. Cherries, Crabapples, Ornamental Pears and Magnolias are in stock and ready for planting. Should you require a large tree for a special spot now is the time to shop!
Prunus x 'Snofozam' - Snofozam Weeping Cherry
Prunus x ‘Snofozam’ – Snofozam Weeping Cherry
Prunus 'Okame' Clump Form'
Prunus ‘Okame’ – Okame Clump-Form Cherry
Prunus x yedoensis
Prunus x yedoensis – Yoshino Cherry