What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

Apples Ready To Pick?

Posted by Hugh on August 27th, 2012

'Gravenstein' apples espalier trained to wall

This unusually hot summer has sped up the harvest time of your backyard apple crop. Here are five good indicators that the apples are ready to harvest.

Change in skin color is one of the easiest for gardeners to spot. The green skin pigment gradually matures to red, yellow or oft green, depending on variety. Photos in fruit nursery catalogs, many available on-line, are good resources for fruit color. Some varieties will develop red skin color before they’re fully ripened, so color should not be your only indicator of maturity. The bottom of the apple (calyx end) turns from green to light-yellow.

On some varieties fruit shape is another change. Red Delicious and many varietal sports form 4-5 nubbins (raised bumps) on the bottom. The nubbin formation is dictated by the region where the variety is grown. Red Delicious from the Northwest U.S. is most to type, while those produced in the warm southeastern states less so.

Next harvest tip is flavor. Bite into an apple and determine its taste. You may not know what kind of apple that you’re eating, but its flavor and sweetness may be what you like. Apples which are hard to bite into or have a sour or starchy flavor are not ready. The inside flesh color often changes from oft-green to white, sometimes to yellow.

The number of days (interval) from bloom period to harvest date can be a reliable guide. Extremely hot summer weather may move up the harvest interval by 7 to 10 days. The approximate picking intervals of popular varieties are: Gala and McIntosh @ 110-115; Empire, Jonagold, and Jonathan @135-140; Red Delicious and Golden Delicious @ 145-150; and Rome, Granny Smith, and Winesap @155-160 days.

Finally, if you harvest too early, apples will be of smaller size, but will ripen off the tree indoors.

Winter Hardiness of Crape Myrtles

Posted by Hugh on August 25th, 2012

Awesome bark on Lagerstroemia fauriei

If you garden in USDA zone 6, certain crape myrtle cultivars are rated as reliably winter hardy perennials. Most dependable are the U.S. National Arboretum cultivars released starting in the 1980’s to date. Each one is named for an Indian tribe. Most of the National Arboretum cultivars are selected for cold hardiness as well as for disease and insect resistance.

Among the cold hardiest (zone 6-b) are the popular ‘ Natchez’ (26-28 feet/ white flowering tree form). This should be the first crape myrtle to trial in your landscape. Also worth trying are ‘Acoma’ (5-10 feet/white flowering), ‘Apalachee’ (11-16 feet/light lavender), ‘Hopi’ (8-10 feet/medium pink), ‘Sioux’ (10-16 feet/dark pink), ‘Tonto’ (8-10 feet/maroon red flowers), ‘Tuscarora’ (26 feet/dark pink), and ‘Pocomoke’ (3-5 feet/dark pink flowers).

Plant crape myrtles in well-drained soil and in full day sunlight. During the initial year of planting, water and mulch the crape myrtle when natural rainfall falls short. Fertilize with 10-10-10 fertilizer or equivalent following spring planting and repeat every spring hereafter.

Living in zone 6, expect that out of every three winters will kill crape myrtle(s) to the ground. To prevent winter injury, never prune a crape myrtle in the fall or early winter. The pruning cuts often do not heal over and the wood may be killed. Sudden spring cold snaps may also injure the growth buds. Wait until mid-spring to evaluate the harshness of the past winter before acting.

The rootsystem is very hardy and will push up new shoots in the spring. Crape myrtle blooms on new wood, and summer flowering is not lost. Yes, your winter injured crape myrtle may be smaller, but it often survives and flowers.

‘Senorita Rosalita’ – A Welcome Spider Flower Addition

Posted by Hugh on August 23rd, 2012

Señorita Rosalita spider flower

Cleome or spider flower (Cleome hassleriana) is the 5-6 foot flowering annual that your grandmother grew in her garden. Long stamens extending from the flowers look like spider legs, hence the common name. The old fashioned varieties produced lots of seed pods which meant lots of weed seed in next year’s garden. As summer temperatures rose, flower power declined and lower leaves dried up.

Señorita Rosalita is a vastly improved cultivar, displaying medium green leaves on a 3 to 4 feet tall upright branched plant, topped by brightly colored flowers. It flowers continuously through the heat of summer up to autumn frost. Flowers are spidery clusters of 4-petaled lavender-pink flowers 3 to 5 inches across. The gorgeous blooms should catch anyone’s attention in flower borders and in large planters.

Señorita Rosalita flowers are sterile, which means no seeds. It exhibits tremendous heat and drought tolerance which means no leafless stems in late summer. Señorita Rosalita has no sticky stems or thorns. Flowers are produced all over the compact plant. Plants exhibit an upright growth habit, maturing from 24 to 48 inches tall, depending on soil moisture and nutrition over the growing year.

This South American native grows best in full sun. Space transplants 18-24 inches apart in well-drained soil. Add 1-2 lbs of 10-10-10 or equivalent fertilizer per 100 sq. ft. of garden bed at planting time. Supplement with a water soluble fertilizer (Miracle-Gro®, Schultz®, or Hollytone®) at the start of summer and 6 weeks later. Señorita Rosalita is self-cleaning, and requires no special deadheading. Irrigate regularly for the first 3-4 weeks until established so that cleome can handle summer’s heat and humidity. The foliage and flowers stay mostly disease and pest free all summer long.

How To Re-Bloom a Moth Orchid (Phalaenopsis)

Posted by Hugh on August 22nd, 2012

Phalaenopsis moth orchids for sale at garden center

Perhaps this past year a friend gifted you a lovely moth orchid (Phalaenopsis spp.). Late summer and early fall is an excellent time to re-bloom it, if you live in USDA hardiness zones 6 through 8. The overall health of the plant should be good. Moth orchids require a fluctuation of between 15 – 20°F in day/night air temperatures for 4-6 week period to initiate flowering. Flower stalk(s) should appear 4-6 months later.

Moth orchids thrive outdoors in the spring and summer months at temperatures between 50 and 90°F. By late summer, the cooler temps have triggered the flowering mechanism. Occasionally plants must be moved indoors on cool (<50°F) nights. In the fall moth orchids are moved to a window with an eastern exposure to the morning sun. Direct morning sunlight may burn orchid leaves in the spring and summer months, but not in the fall and winter.

In the fall plants do benefit from re-potting. Use a commercial orchid mix available at many local garden centers and big hardware store chains. Remove the pot and inspect the quality of the root system. Clip off broken, shriveled or rooted roots using a sharp knife or shears. If the roots are over-crowded in the old container, re-pot in a container slightly larger. Water the orchid thoroughly after potting, and wait 2-3 weeks before fertilizing it the first time.

Fertilize orchids weekly in spring, summer and fall with a high phosphorus-based orchid fertilizer. During the winter, feed once monthly. Group plants together sitting in shallow trays filled with moistened gravel. Mist leaves one or more times daily to raise room humidity around the orchids.

In the late winter and spring one or more flower stalks should emerge. Use a twist’em to tie stalk(s) to a 12-18 inch tall stake as needed. Rotate the plant every 2-3 days to keep floral stalk growing straight. After all flower petals have fallen, remove the spent floral stalk.

Star Zinnias Handle Heat and Dry Weather

Posted by Hugh on August 21st, 2012

'Zahara Starlight Rose'

Wanting two seasons of spring-summer color, heat and drought tolerant, and no disease or pest problems? You should be planting Profusion and Zahara zinnias, also called “star zinnias”. They are very resistant to powdery mildew, a disease which plagues many kinds of zinnias.

Profusion and Zahara zinnias bloom non-stop for almost 6 months (mid-May thru October) in the Southern Appalachian region (USDA hardiness zones 6 and 7) before losing out to a November freeze. My favorites in the Profusion series are Apricot, Orange and Cherry. White, Yellow, Fire and Double Cherry Red are also available.

Zahara bears flowers 20% larger than the Profusion series. Zahara zinnias come in a wide range of colors, from white to scarlet. ‘Starlight Rose’ (photo) features white petals splashed with bright red around its floral button center. ‘Double Cherry’ (deep magenta) and ‘Double Fire’ (scarlet orange) are double flowered cultivars.

Flower sizes range from 2 to 3 inches in diameter. The colorful daisy-like blooms will attract numerous butterflies to your garden. Flowers are self-cleaning, requiring very little deadheading. Plants grow compact and well-branched at 18 to 20 inches high and wide. Plants should be spaced 8 to 10 inches apart in flower garden beds or in containers.

Star zinnias perform best in the full sun with good fertility. Add 2 to 3 inches of mulch to improve soil organic matter and to reduce soil moisture loss. Irrigate during extreme dry spells to maintain plant health, vigor, and flower numbers. At spring planting, feed with a slow-release fertilizer. Supplement nutrition with a water-soluble fertilizer (such as Miracle-Gro®, Schultz®, or Hollytone®) every 2-3 weeks during the summer period.

Fall In Love With Sweetheart Tree

Posted by Hugh on August 20th, 2012

Korean Sweetheart tree (Euscaphis)

The late J.C. Raulston introduced euscaphus tree (Euscaphus japonica) to gardeners in the 1980’s. Tennessee nurseryman Don Shadow is credited with naming it “Korean sweetheart tree” which has become its more popular name. It is reliably winter hardy to USDA zone 6-b.

Sweetheart tree is a small 15-20 foot tree or large shrub. The pinnately compound foliage is comprised of 7-11 leaflets which are glossy and feel thick to the touch. Leaflets hold their dark green color through the summer months. Foliage reportedly turns burgundy red in the autumn, but my tree of 20 years has finished greenish yellow every year.

A young tree branches low to the ground and its bark has a brownish purple skin with thin white lines running vertically. A 25 years and older tree exhibits a dark gray bark.

Small terminal clusters of creamy white flowers open in late May and early June. While flowers are noticeable through the compound foliage, they are not stunning compared to many showier trees and shrubs also blooming at this time.

In late summer the bright red fruits will likely capture your attention. Multiples of 1/2 inch wide, heart shaped seed capsules are grouped together, and turn cherry red in early September. The capsules open to reveal 1-3 shiny black seeds within.

Sweetheart tree grows best in a compost rich, well-drained, and moderately acidic garden soil. Grow sweetheart tree in full sun (under irrigation) or in part shade (2-3 hours sunlight and no irrigation).

Strong Vertical Presence of Serbian Spruce

Posted by Hugh on August 17th, 2012

Serbian spruce at Arnold Arboretum in Boston

Serbian spruce (Picea omorika) rises as a tall spire in the urban landscape. A mature tree may reach 50 to 60 feet high and it creates a narrow footprint of 15 to 25 feet wide. Lateral branches uniquely bend downward while the growing tips sweep gracefully upward.

Annual growth rate is slow at 12-15 inches. Two-thirds of the short dark green needles lay flat. Needles are lustrous on the upper surface with two prominent white bands on the underside. Oval-shaped 2 ½ inches long cones hang downward, bluish-black early and light cinnamon at maturity.

Serbian spruce is highly adaptable. It grows well in full or partial sunlight (6 hours recommended) and rooted in moist well-drained soils with a wide pH range. A 3-year and older established tree handles summer dry spells and rough urban environs. A nursery-grown tree transplants well in the early fall or late winter periods from container or balled and burlapped (B&B) stock. It is northern hardy to USDA hardiness zone 4 and with good heat tolerance to zone 7-a. It becomes heat challenged past this point.

Serbian spruce deserves a more prominent place in commercial and residential landscapes. Few diseases and pests trouble this staturesque tree. You can group several together as a windbreak or privacy screen or plant a single specimen, where ground space may not be plentiful.

If you are searching for an alternative to the oft-used Norway and Colorado spruces, try Serbian spruce. Dwarf and weeping cultivars are also available through e-commerce specialty conifer nurseries on-line.

Common Ditch Lilies

Posted by Hugh on August 14th, 2012

Hemerocallis fulva

A native of eastern Asia, tawny daylilies (Hemerocallis fulva) are often called “ditch lilies”. You see them growing along roadsides, in back alleys, and in old gardens, often in very poor soil. Their tenacious root system helps to stabilize steep slopes. They seem to thrive in places too difficult for most plants. They’re grow so easily that they eventuallyspread and become a nuisance.

They start blooming in late June in USDA zones 6 and 7. The 4 ½ inch diameter pale orange flowers are borne on sturdy 5- 6 foot tall floral scapes. Flowers last one day, and each scape bears multiple floral buds which open over a 3-5 week period. They come in a rainbow of flower colors, but orange is the most common. Some H. fulva cultivars are sterile and are less of a potential nuisance.

Ditch lilies prefer full or partial sun. In the lower South (USDA zones 7-b thru 9), ditch lilies are best sheltered from direct sunlight. Soils should be moist, loamy, slightly acidic, and well-drained. Fertilize with 10-10-10 or equivalent in early spring when new growth starts up and again in midsummer.

Ditch lilies form large thick clumps of arching, strap-like bright green leaves. Established clumps cope with summer heat and drought spells. Ditch lilies will grow in semi-shade, but produce more foliage and less flowers.

Group ditch lilies together in the wide border to naturalize. Because of their invasive tendencies, ditch lilies are ideal for planting in confined spaces such as in parking lot islands or in median strips on a busy highway.

They have few problems with pests and foliar diseases. Clumps spread quickly and should be dug up and divided every 4-5 years in early autumn. Occasionally, flower scapes develop aerial plant/root proliferations which can be easily rooted.

‘Hot Lips’ Turtlehead – A Late Summer Flowering Native

Posted by Hugh on August 8th, 2012

Turtlehead (Chelone) in late August

Turtlehead (Chelone spp.) is a U.S. native. Turtle-head shaped flowers appear in August and September. The 1 inch flowers open from bottom to top along the stem (s). Colors vary from bright white, creamy white, and white tinged with pink (depending on species and cultivar grown).

Pink turtlehead (C. lyonii ) is native to the Southern Appalachian region (USDA zones 5-8) and is an upright, clump-forming, rhizomatous perennial. It typically grows 2-4′ tall on stiff, square stems. New leaves emerge bronze green in early spring and quickly turns dark green. Full leaves are coarsely-toothed and up to 6 inches long.

Turtlehead grows sturdy in a compost rich, medium to wet soil in full or partial sunlight (6-hours minimum). Plants become floppy when grown in part to deep shade and often require staking. Be wary that turtlehead disperses seeds around the garden. No disease and pest problems are generally the rule, but powdery mildew may pop up if turtlehead becomes stressed out in dry soils or air circulation around plants is poor.

Butterflies, hummingbirds and other pollinators are attracted to turtlehead, and the plants are deer resistant. ‘Hot Lips’ turtlehead is an outstanding selection of C. lyonii with dark green foliage and knockout deep pink colored flowers. ‘Hot Lips’ stands 2-3 feet tall on sturdy deep red stems.

Ostrich Fern Likes It Moist And Cool

Posted by Hugh on August 6th, 2012

Slight Drought Injury on Ostrich fern (Matteuccia struthiopteris)

For sheer toughness ostrich fern (Matteuccia struthiopteris) handles most landscape situations (USDA hardiness zones 2-7a). Ostrich fern is commonly seen growing naturally in cool moist river bottom soils, 3-5 feet in height and spreading aggressively. Roots have a clumping rhizomatous nature. The fronds grow upright with a slightly arching form, typically to 2-3 feet in height under average garden care.

Ostrich fern is a deciduous fern which prefers moist, well-drained, slightly acidic to low alkaline pH soils in full to partial shade. It is no fan of drought, high heat and humidity and can only survive in cool moist shade in southern zone 7-a.

Ostrich fern earns its name for their feathery long “ostrich -like plumes”. In early spring the vegetative fronds emerge from a narrow pedestal or base as “fiddleheads”, which unfurl to a maximum length of 3-4 feet. The emerging fiddleheads (new fronds) are said to be quite delicious sautéed in oil or butter. By mid-summer the 2 foot spike-like fertile fronds arise in the center and turn dark brown and woody by late summer.

Well-established 2-3 year old clumps can survive in non-irrigated ground, but the vegetative fronds may appear brown and tattered. Medium green fronds mature to dark brown in mid- to late autumn.

No serious insect or disease problems trouble them. Group several together in moist woodland areas or adjacent to streams or ponds. Plant ostrich ferns with other shade garden favorites such as heucheras, astilbes, lungworts (Pulmonaria), hostas, and hakone grass.