Category Archives: Perennials

Horticulture Report: May 2013

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Rhododendrons & Azaleas
What’s the difference between Rhododendrons and azaleas?

Azaleas are Rhododendrons. They belong to the subgenus pentanthera (deciduous) and the subgenus Tsustusti (mostly evergreen).
Azaleas are elepidotes, they never have scales.
Azaleas have five lobes to the flower.
Most azaleas have only one stamen for each lobe of the flower, while most other rhododendrons have two stamens for each lobe.
Azaleas tend to have appressed hairs (hairs that grow parallel to the surface of the leaf). This is particularly true along the midrib of the under-surface of the leaf and is easily seen in the so called “evergreen” azaleas.
Azaleas have tubular funnel or funnel shaped flowers. You need a microscope to see this, but the hair on a “standard” rhododendron will often branch, while the hair on azaleas never does.

Basic Needs:
Rhododendrons must have a constant supply of moisture.
They are sensitive to poorly drained conditions.
Hot wet conditions are more dangerous than cool, wet conditions.
They need an acid soil of pH 5-6.
Fertilizer: A 10-6-4 formula is optimal. For the best growth and flowers apply fertilizer after the plant goes dormant between late Nov and Jan, a second application in Feb or March, a third time in April or May, and a final time in June or July.

Pruning:
Always prune right after flowering. Even large plants can be cut back. Rhododendrons & azaleas flower on the prior year’s wood, therefore the buds for next spring’s flowers form during the previous summer or fall. If you prune them later in the summer, fall or winter you will be trimming off your flowers for the spring.
Prune larger leaved rhododendrons just above the growth joints.
Prune azaleas and small leafed rhododendrons anywhere along the stem. These plants have dormant growth buds nearly everywhere, though you may not be able to see them.

Deadheading and Pinching:
Light pruning and shaping should be done yearly when you deadhead. Snap off the old flower trusses. You may pinch out the single terminal growth buds just as they start to grow. It will make a shorter and bushier plant.

For more information:
American Rhododendron Society
http://www.rhododendron.org/

American Azalea Society
http://azaleas.org/

Definitions:
Elepidotes are large leaved rhododendrons. They are the type of shrub that most individuals would associate as being a rhododendron. They do not have scales located on the underside of the leaves. Plants tend to be very large in their maturity.

Lepidote rhododendron have smaller leaves and are usually low growing or dwarfs. They usually bloom earlier in the spring than the larger leaved elepidotes. Tiny scales cover the undersides of the leaves of some rhododendron species.

Horticulture Report: February 2013

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BULBS TO PLANT IN THE SPRING

Iris: There are over 200 iris species.  Some grow from rhizomes, most common, others from bulbs.   Irises do best with plenty of sunlight and planted in soil that is fertile and well drained.   Don’t be too generous with fertilizer as it will produce lots of plants and few flowers. Plant iris rhizomes horizontally one foot apart and plant them shallow, just barely cover with soil. When blooms are finished cut faded flowers off to prevent seeds pods from forming, as these pods can weaken the plant.  Deer won’t eat iris, so, many gardeners claim irises have no pest except dogs, cats and children, who can jump on them breaking their stems.   Irises do not need mulching and they do not like overhead watering.

Crocus:  Autumn Crocus (Colchicum autumnale) resembles spring crocuses with white, lavender and rose colored flowers, but they bloom in the fall.  You can plant Autumn Crocuses in early spring. They like light, loamy soil with good drainage. Plant them 3-4 inches deep in a sunny location.  After blooming, let them die back naturally, do not “mow” them down.   The corms should be divided every 3-4 years to stop overcrowding or they will stop flowering. Autumn Crocuses are hardy in zones 5 & 6.

Saffron Crocus (Crocus Sativus) blooms with lavender or white flowers. Sativus’ stigmas (stamens) are the source of saffron, but in case you were thinking of raising them for saffron, it takes thousands of stigmas to produce one ounce of saffron.

Colchicum (Meadow Saffron) and Autumn Crocuses (Colchicum autumnale) are often confused with each other because they are both considered an autumn crocus, and their blooms are very similar. However colchicum is its own genus with at least 15 species, hybrids, and varieties. Colchicums are taller too, growing up to 8” in height and they are more expensive to buy. Be aware that colchicum corms contain a deadly toxic, so wear gloves when working with them.

Autumn Crocus belongs to the Lily family (Liliaceae) along with Lilies, Tulips, and Hyacinths while spring flowering crocuses are a member of the Iris family (Iridaceae) along with Irises and Gladiolus.

Allium:  The Allium, which is Latin for garlic, includes chives leeks, shallots, onions and of course, garlic.  Some members of Allium family are ornamental perennials which produce globe-like flowers. These flowers can be used in arrangements either freshly cut or dried. Plant ornamental Allium bulbs to a depth that’s 2 -3 times the diameter of the bulb, space them 6-12 inches apart. Plant bulbs in full sun and in ordinary soil. It flowers in many different colors and sizes. They don’t ‘have pests.

Gladiolus:  Gladioluses are members of the Iris family, and most of the 200 species are natives to Africa.   Their name comes from “gladius”, which is the Latin name for sword because of their sword-like foliage. Their flowers are borne on spikes 1-5 feet tall.

Plant bulbs in a sunny location 3-8 inches deep, and they look best planted in groups of 6-12 plants of the same color, rather than as an individual plant, or in groups of mixed colors.

Lilium: Lilies are among the most beautiful of the summer blooming flowers.   Historically, lilies were not easy to grow in North America because, unlike other bulbs, lilies never grow dormant. This made it difficult to ship in good condition and often they were infected with viruses. Then Jan de Graaff, who was born in Holland in 1903, became fascinated with Lilies.  In 1928, he started working for the Oregon Bulb Farms, and then in 1924 he bought the company.  After making thousands of lily crosses his flower called Enchantment was instantly success so he began marking lilies successfully.

Lily bulbs deteriorate rapidly, so plant right away. Lilies like very well drained acid soil enriched with enough humus to hold the moisture they need.  Plant bulbs 5-8 inches in a location with full sun until noon then shade in the afternoon. Lilies do well in large deep planters or pots with good drainage.   To discourage diseases water so no moisture stays on the foliage.   Fertilize with fish emulsion or seaweed.    However, the Madonna Lily and the Turks Cap only need their tops 1‘’ below the soil.  . Lilies have a reputation for a short life, therefore the need placing every 3 years.

Dahlias: Few plants offer such a variety of shapes sizes and color and long season of bloom as the Dahlia. It is a member of the daisy family and is a native to Mexico. After the Swedish born botanist Anders Dahl developed several hybrids, the plant was named after him.

Dahlias like rich, deeply tilled, loamy  soil and full sun, but protected from winds .  Do not plant near trees and other plants that will compete with them.   Dahlias over 4 feet tall must be staked because their stems are hollow and brittle.  Insert the stake into the ground before planting so you won’t damage the tuber,  Dahlias like plenty of nourishment and water, so be sure to give it  plenty of compost and manure.

Dahlias that grow over 4 feet tall should be planted 1 foot deep then covered with only 3-4 inches of soil.   After the stem break the surface, add more soil, repeat this until the top of the hole is reach. As it grows pinch off terminal buds to stimulate side branching and encourage a more bushy plant. There are also shorter varieties available now which grow only 2 ½ ft. high. These shorter versions can be grown in a large container.

The ground should be warm before planting Dahlias. To plant, lay tubers horizontally 4-6 inches deep and 18 inches apart, and do not water them after planting.  Give them a low nitrogen fertilizer, but don’t over feed them, and hand weed only.

Dahlias tubers are “thin skinned”, so they are not has cold hardy as a bulb, therefore it’s recommended they be dug up and store for the winter.  However, if you decided to leave them in the ground, cut their stems below the ground level in June. Then in mid-November cover your Dahlia area with plastic to keep the winter rains off of the tubers and add a few inches of leaves, mulch, soil or straw over the plastic to give them extra warmth.   Remove this protected cover in March.

by Mary Anne Wallace

Mums the word!

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There are over 5,00 varies of mums, but only common garden varieties are usually found at local nurseries. Check online if you are looking for unusual ones, or ask your local nurseryman if they can order a specific variety for you.

Guide to chrysantheMUMS:
  • Select mums that match your hardiness zone. Mums are available in both tender and hardy perennials.
  • Plant mums in full sun, they need at least 6 hours daily.
  • Mums like well draining soil. Boost soil with compost and fertilize mums every 4-6 weeks with a water-soluble fertilizer during the growing season.

  • Never let mums wilt! Water often and do not let them dry out.
  • Watch for pest,  and treat plants with insecticidal soap, if needed.
  • Pinch spent blooms to encourage more blossoms and to keep plant bushy.
  • Mums bloom at different times during the season; there are early, mid, and late blooming varieties. Fall mums will continue blooming until a hard freeze.

~Carlotta

Blue False Indigo

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Baptisia australis (Blue False Indigo)

This North American prairie native is long lived but slow growing, so it can take up to 3 years to bloom. It is an easy to care for plant which tolerates both clay and sandy soils. Blue False Indigo is excellent for cut flowers and attracting butterflies.

Form: Spiky architectural vase shaped: 3-4 feet high, 1½ -3 feet wide

Exposure: Full sun

Color: Striking pea-like purple flower stalks, blue-green foliage

Bloom Time: June – July

Attributes: Drought tolerant, suitable for xeriscaping, deer resistant (Note: Parts of the plant are poisonous if ingested!) Average Water Needs, water regularly but do not over water.

USDA Hardiness Zone: 3A – 10B

Bigroot Geranium

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Bigroot Geranium (Geranium macrorrhizum)

Geranium macrorrhizum is a hardy perennial that blooms prolifically in the spring. Some varieties also present outstanding leaf color in the fall.Bigroot Geranium is deer- resistant, so “typically” deer leave it alone. Plant your geranium in full sun or partial shade. It’s not too picky about growing conditions, except it doesn’t like wet boggy areas, so plant in well-draining soil. It grows 1 to 3 feet high and 2 to 3 feet wide. Geranium makes a good groundcover at the base of trees, shrubs and taller perennials. Geranium macrorrhizum varieties include: Album which produces white flowers, Ingwersen flowers in pink, and Variegatum, with white-variegated leaves, which produce purple & pink blossoms. Note: Variegatum likes richer soil and keep it out of full sun. USDA Hardiness Zone: Zones 4-8

Horticulture Report: February 2011

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Deer Proof Plants: The following are summaries of perennials from the book:
50 Beautiful Deer-Resistant Plants: Thee Prettiest Annuals,
Perennials, bulbs and shrubs that Deer Don’t Eat
by Ruth Clausen
(May 30, 2011)

Perennials Part 1 –AZURE MONKSHOOD (Aconitum carmichaelii)

All parts of this plant especially the roots are poisonous. Monkshhood grow 2 to 3 feet tall and have deeply cut leaves and dark blue spikes of flowers. It grows in the sun or light shade in zones 3-7 and the tuberous roots can be divided in the fall. Be very careful not to get the sap on your skin. This plant is also known as wolfs bane, tiger bane and leopard’s bane.

BIGROOT CRANESBILL GERANIUM (Geranium macrorrhizum)

This plant is a low maintenance ground cover covered with 1-2 inch flowers.The leaves are a light fuzzy light green.It has a scent when any part of the plant is bruised which the deer hate but which in Europe is used in skin care products.

BLUE FALSE INDIGO (Baptisia australis)
Blue false indigo is drought tolerant and almost totally pest and disease free.Plant it in a sunny area in well drained not too rich soil.It grows 3-4 feet tall in zones 3-9.It is a good mixture with yarrow or salvias butterfly bush and Russian sage The seeds are poisonous to deer.

CUSHION SPURGE (euphorbia polychroma) The genus Euphorbia has some 2,000 or more plants all of which are more or less avoided by deer.When working around Euphorbias wear long sleeves and gloves and avoid contact with the skin as it can cause dermatitis. Do not get sap in the eyes. Cushion Spurge makes neat rounded mounds of light green leafy stems topped in the spring by chartreuse flowers which are surrounded byyellow bracts.Plant it in light shade and cut back after flowering.It tolerates drought conditions very well.

FRINGED BLEEDING HEART (Dicentra eximia) The fringed bleeding heartis similar to the common bleeding heart but the plants are lower growing and bloom repeatedly through the season.Their fernlike foliage remains good-looking through hot days.It likes shady gardens and does well with astilbes, wild geraniums and fernsespecially Japanese painted fern.They are completely deer resistant due to their poisonous sap.

ASTILBE (Astilbe arendsii) Astilbes are wonderful when massed together and grown in part shade moist soil which is high in humus.Deer apparently don not like the fern like texture of astilbe leaves.The colors range from white to red to all shades of pink.They make good, long lasting flowers {cut when half open) for arrangements.After the flowers have faded on the plantyou can let them stay on to provide decorative value.

HYBRID SAGE Salvia sylvestris) Sages include both ornamental as well as culinary herbs} Butterflies and hummingbirds are attracted to the flowers whereas deer are repelled by their smell. Sage is best grown in well-drained soil in full sun. ‘May Night’ Sage which has spikes of violet blue flowers was named the Perennial Plant in 1997.

JAPANESE SPURGE (Pachysandra terminalis) Japanese Spurge is a ground cover just called Pachysandra.As a ground cover plant it 6-12 inches apart in light or full shade in humus rich, well drained but moist soil.It has no equal as a ground cover in full shade under tall trees (even black walnut)However do not plant spring bulbs with it as it is a greedy plant.

By Mary Ann Wallace and Gena Goddard