Category Archives: perennials

Chrysanthemums

 I can think of only a handful of perennials that bloom so easily, so prolifically and come in so many colors as the chrysanthemum.   Although they will be available throughout fall, the best supplies are often found now.  If you need to perk up your tired containers of flower beds, think of the reliable mum.

Actually, their botanical name has been changed to dendranthemum grandiflorum but I never hear anyone use this name.  It doesn’t exactly roll off the tongue.
Purple Mums

Mums represent the changing season with their bonze, yellow, orange and red tones.  Other flower colors include pink, lavender, purple and white to match any color scheme you might have.

Grown for years to flower only in late summer and fall, they are short day plants, setting buds when they receive light for 10 hours and darkness for the other 14 hours of the day.  This is why mums bloom in the spring on leggy stems if they are not cut back.  And this is how growers manipulate their blooming, adjusting the dark and light periods with shades in the greenhouse so buds will form in any month.   They’re nearly constantly available in grocery stores and florists in every season.

    At this time of year, garden mums abound.  Pick a plant with lots of buds, they bloom only once and won’t set more flowers until next year.  Those buds, though, last a long time if you don’t let them dry out. The specific type of plant doesn’t matter since they all have long term growth potential.  There is a European mum that produces hundreds of buds and stays relatively small and compact when set out in the garden.  If you particularly like one color or form of chrysanthemum, plant it now to enjoy again next year.  You never know what the growers might decide to grow next season.

Choose a well-drained, sunny spot to plant them.  Like many members of the daisy family, mums don’t tolerate soggy ground.  After blooming, trim off the old flowers and cut back plants to within 6-8" of the ground.  If you started with 4" pots trim back by half.

Next spring pinch them back whenever growth gets to 8" tall.  Keep pinching until July, then allow plants to start forming buds for the traditional fall show.  Mums need regular water so plant them in spots where you have other plants with the same water needs.

This fall, add to your mum collection or start a new one.  The pungent scent of their leaf reminds us that cooler weather is on the way.  And don’t forget to cut some for a bouquet to bring inside the house.
    
 

Groundcovers

Ground covers are like a fancy carpet in the garden.  They add richness and beauty under trees and become the stars of the show in sunny apots.  Ground covers reduce maintenance by preventing weeds and reduce watering by acting as a living mulch.  

 

When choosing ground covers, assess the conditions of the area you want to plant.

  •  Is it in the sun or shade?
  •  Is it a naturally moist area or dry?
  •  Do you intend to water it or go with our natural cycle of wet in the winter and dry in the summer?
  •  Matching the plant to the site conditions will ensure success.

When designing a plant layout I consider whether I want a sweep of the same plant or a tapestry effect with a variety of plants.  Using more than one type of plant allows me to work with foliage contrast adding pattern to my composition. 

Splash color and texture on the ground under trees and shrubs with shade-loving ground covers like   Serbian bellflower.  It needs little water, blooms with star-shaped 1/2" blue flowers in spring and summer and spreads vigorously without becoming invasive.  Heart shaped foliage covers this mounding plant.

Lamiastrum is another perennial ground cover for partial or full shade.  Silvery variegated foliage can lighten up dark corners and small yellow flowers are a bonus in late spring.

To preserve good visibility along a walkway or lawn, use low-growing, long blooming perennials like diascia, Santa Barbara daisy and achillea.   All prefer full sun and moderate to little water.

 

Diascia is a So. African native with 1/2" wide flowers that appear on the ends of spreading stems.  Pink used to be the only flower color but now hybridizers have developed apricot, coral and lavender, too.  Diascia’s are hardy to 0 degrees and bloom nearly continuously if old flowers are cut off after flowering.

 

Santa Barbara daisy has become a popular ground cover as it reseeds readily and can cover a large area fairly quickly.  This 10-20" tall trailing plan spreads rapidly to about 2 ft, making it a great filler between larger shrubs and perennials.  Dainty 1/3" pinkish white flowers cool down hot sunny spots.  Trim this plant several times a year to keep tidy and encourage blooming.  

 

Achillea or yarrow are among the most carefree perennials for summer and early fall bloom.   They spread by underground runners and make great ground covers. Keep this in mind if you have a limited space.   The most common variety is Summer Pastels but if you want to add a punch of color to your garden, plant Cerise Queen with it’s cherry red flowers.   

 

Rockrose provide large-scale cover for expansive sunny areas.  Their dense strong root systems help prevent soil erosion.   Choose from white, pink or magenta flowers on plants varying from 1-5 ft. high depending on which variety you choose.  This Mediterranean native is fast growing and drought tolerant. 

 

To create stunning combinations of ground cover plants. choose 5 or 6 styles and repeat them in small drifts to carry the eye through the composition.

 

Add grasses for linear texture.  Good candidates are Blue Oat grass, a non-spreading clumping grass with silver leaves.  Carex Ice Dance is a spectacular evergreen ornamental grass with dark green narrow foliage edged with a pure white border.  Ice Dance spreads by underground runners in partial sun or shade.

 

Take the opportunity to survey your garden for bare spaces that can come alive with added texture and color.  


Echinacea

Echinacea Need more late summer perennials to extend your season?  Purple coneflowers will continue to bloom until frost then go dormant for the winter.  Showy 4" rosy purple daisies are lightly fragrant and make good cut flowers for bouquets.  The clumps spread slowly and can be carefully divided after 3 or 4 years.  There is also a beautiful white variety called White Swan.  If faded flowers are left in place, the bristly seed heads provide food for finches in winter.  

The herb echinacea is derived from varieties of this flower.  E. angustifolia is used nowadays as a fortifier of the immune system, mainly to prevent flu and minor respiratory diseases by increasing the body’s production of interferon.  The roots are the part of this plant used for medicinal purposes.   Echinacea was used by Native Americans more than any other plant in the plains states.  It’s antiseptic properties were used to treat snake and insect bites, to bathe burns and to help cure the “sweats.”  They chewed the plants roots to ease the pain of toothache.  It was also used by the Native Americans for purification.  The leaves and the flowers can be used in teas as well.

Gloriosa Daisy ‘Prairie Sun’

Gloriosa Daisy 'Prairie Sun'

Late summer color can be an opportunity to add new plant that will bring beauty to your garden right through fall.  Many summer annuals are leggy and in need of cutting back about now.  If you like spending time outdoors at this time of year take advantage of this glorious weather and make sure your garden has lots of colorful flowers. 

Golden yellow perennials like gloriosa daisies, coreopsis and golden mums stand up to strong sun now, and later in the season burn like embers under gray skies.  You’re probably familiar with the traditional Black-eyed Susan with a prominent purplish black cone in the center.  There are many varieties of this type with russet, bronze or mahogany bands.  But a gloriosa daisy I especially like has huge 5" golden yellow blooms with pale yellow tips and sports a light green central cone instead of the familiar brown one.  Prairie Sun looks stunning with any shade of blue or lavender like asters, Russian sage or salvias.  Try it in front of the sky blue flowers of cape plumbago for a breathtaking combination.

Gloriosa daisies make good cut flowers and are tough and easy to grow.  They are descended from wild plants native to the eastern US and require only moderate water once established. 

Planting under mature trees

lush plants under mature trees

We live under oaks and are surrounded by redwoods. We know the value of trees in the landscape. Trees shade us in the summer. Their showy blossoms herald a much awaited spring and their colorful foliage in the fall quietly marks the end of the growing season. You can hang a hammock between two of them or tie a rope swing for the kids from a large branch. Yes, trees are our companions, but how can you create a garden under one of them?

Planting under a mature tree can be a challenge. Caution is required to avoid damaging their roots and the plants will need to cope with dry soil, shade, root competition and ever-changing moisture and light conditions. You want both your new plants and your tree to thrive.

Meet your tree’s needs first. Some trees are more agreeable than others about giving up some of their ground. You can still plant beneath trees that are sensitive to having their roots disturbed, but you’ll need to make a few concessions. When purchasing plants to grow under trees, think small. Small plants require a smaller planting hole and this will minimize disturbance to the roots. You may have to buy more plants but you’ll have an easier time tucking them among the roots.
Don’t alter the grade of the soil or change the soil pH very much. Even adding a layer of soil that is more than 2" deep can reduce the amount of moisture and oxygen available to the tree and hinder gas exchange to existing roots, causing trees to suffer or even die.

Only the toughest plants have a chance of surviving among the surface roots of shallow rooted trees. Be careful when disturbing sugar maples, elms. cherries and plums, dogwoods, magnolias, pines and oaks. The majority of a trees roots are small woody roots and fine hair roots that grow within the upper 12-18" of soil and extend far beyond the trees drip line. These roots are responsible for absorbing water and nutrients from the soil.

If you encounter a root larger than 1 1/2 – 2" in diameter while digging a hole for a plant, move the planting hole a few inches away to avoid slicing through the root. You will sever mats of small tree roots when digging, but they’ll regenerate fairly quickly.
To avoid wounding the bark, which may cause insect and disease problems, start planting at least 12" away from the trunk. Oaks, remember, shouldn’t have any plantings closer than 6-10 feet from the trunk and those should be drought tolerant. After planting, water to settle the soil and spread 2-3" of mulch to conserve moisture and keep weeds down. Be sure to keep mulch at least 12" away from the base of the tree. Mulch can hold moisture against a tree’s bark and cause rot and disease.
Trees that will tolerate some disturbance to the root zone include Eastern redbuds( both the green-leafed species and the purple- leafed Forest Pansy ) and red maples ( also a good lawn tree. ).
Common trees that are easy going about planting underneath are crabapples, ginkgos, hawthorns, honey locust, poplars, silver maples and willows.

So what plants will transform your bare patch of hard earth and knobby roots into a shady nook? If you’re going for a lush look, consider hostas and ferns, paired with the hardy geranium Biokova. Other good companions are astilbes with their feathery flower plumes and variegated euonymus fortunei with bergenia or digitalis mertonensis.
Trees with branches limbed high look good with small shrubs planted underneath. Red-leaf barberry can brighten up this spot and also provide fall color. Small nandinas like Harbor Dwarf make a good ground cover and their foliage takes on an orange-red color in winter. Fragrant sarcococca grows well in this situation, too.
Low groundcovers make a simple statement under the crown of a tree. Ajuga, pachysandra and sweet woodruff all grow well here. Or you might like the look of the shade tolerant grass-like plant , cares morrowii ‘Evergold’. This stunning sedge makes a beautiful clump 1-2 ft. high and 2-3 ft wide with dark green leaves and a central band of creamy white.
You can have a beautiful garden under a mature tree by following these tips and conquering this challenging site.

 

Sudden Oak Death Syndrome ( SOD )

InDay Lilypreparing for a consultation for another site under native oak trees at risk for SOD I found the latest host list published by the Sudden Oak DeathTask Force . The new list updated March 2008 also lists plants naturally infected and lots of information re. spreading the fungus as well as tips on sanitation. The latest information on prevention and keeping the immune system of your trees up if also available. I did find that a few of the plants that I was going to recommend for homeowners with oaks on their property have now been listed as vectors. They are coffeeberry, toyon, berberis aquifolium, manzanita and some varieties of ceanothus. This is important information for all of us to know.