Photoperiodism – Short Day/Long Day Plants

'Prestige' poinsettias

‘Prestige’ poinsettias ready for Christmas sales

Fall mums at Longwood Gardens (photo by Jane Conlon)

Fall mums at Longwood Gardens (photo by Jane Conlon)

“Photoperiodism” or daylength is responsible for triggering flowering in numerous plants. Some examples of short day plants are poinsettias (Euphorbia pulcherrima), fall mums (Dendranthemum spp.), asters (Symphyotrichum spp.), Thanksgiving (Schlumbergera truncata), Christmas (S. bridgesii) cacti, Kalanchoes (Kalanchoe spp.) and Salvias (Salvia spp.).

“Photoperiodism” is the amount of light and darkness a plant is exposed to. The amount of uninterrupted darkness on most types of plants bloom is at least 14 hours long nights (dark) and daylight periods are between 8-10 hours for 6 weeks. Streetlights or indoor lighting may disrupt the dark period and greenhouse growers may need to be covered the crop each night.

Another way of defining photoperiodism is short day plants require a longer period of darkness daily. Short-day plants flower only when daylengths are less than 12 hours per day. The length of dark period is most crucial.

Mums, poinsettias and holiday cacti need less than 12 hours of light daily over six continuous weeks from late spring and early summer. Note: holiday cacti will also initiate flower buds when exposed to cool night temperatures between 50-55°F over 4 weeks. However, no flowers will form if night temperatures are consistently above 68°F regardless of light length.

You may also stimulate bloom in long day plants such as lilies, roses, petunias and spinach if daylengths surpass 12 hours. Simply set these plant under lights for a few hours daily beyond natural outdoor daylength for 3-4 weeks. Here, you’re interrupting their night (dark) period.

In a third category are the “day-neutral” plants. They do not depend upon the amount of dark or daylight hours. When these plants reach a certain age or maturity, flower buds are initiated, flowering happens, and later set seeds or fruits. Sunflowers (Helianthus annuus) and tomato are examples of day neutral plants. Strawberries may be classified as either “everbearers”, “June bearers” or “day neutral”, depending on variety.

Key Points About Poinsettias

Healthy closed flowers will look good over the holidays

Healthy closed flowers will look good over the holidays

New Poinsettia Variety 'Ice Crystal'

New Poinsettia Variety ‘Ice Crystal’

The beautiful poinsettia (Euphorbia pulcherrima) has become a symbol of  the Christmas and winter holidays. The showy colorful bracts, that most people think are the flowers, are actually modified leaves. The tiny “true” flowers are in the center of the bracts.

Joel R. Poinsett introduced the poinsettia plant to the United States from Mexico. Poinsett was a botanist, physician and the first U.S. Ambassador to Mexico. In Mexico poinsettia grows as a 10-15 feet tall perennial shrub. In the U.S. plants thrive in Florida and Southern California gardens (zone 9). Here, they’re sometimes planted in late summer where the vivid bract colors add pizzazz to the fall-winter landscape. Plants hold up to night temperatures in the upper 30’s.

A member of the botanical family Euphorbiaceae, leaves and stems ooze milky sap. However, no parts of a poinsettia plant are poisonous. Some people and pets may develop a skin irritation from the sap.

Tips on purchasing: before purchasing the true flowers should be fully formed and tightly closed. If the yellow pollen sacs have shed or the flowers have dried out, do not purchase. Once the flowers start to age, the colorful bracts soon decline. The plant may look poorly on Christmas Day.

Care In The Home: place your poinsettia near a sunny window that faces south or east and room temperatures are between 65 to 75 °F. Poinsettias thrive in a well-drained soilless media (potting mix). Check for dry soil every few days and water thoroughly; excess water should flow freely out the drainage hole in the container. Never leave a poinsettia standing in water for over one-half day as it may cause root injury. Feed the plant every 2-3 weeks with a water soluble fertilizer @ one-half the rate of package directions through the winter months. Your poinsettia may still look beautiful on the first day of spring.

There are more than 100 varieties of poinsettias available today. Varieties come in lots of colors from traditional red, white, pink, burgundy, marbled and speckled.

Purchasing A Cut Christmas Tree

Cut christmas trees for sale

Cut Christmas trees for sale

Christmas Tree Farm in SW Virginia

Christmas Tree Farm in SW Virginia

Around the holidays lots of people head out to local Christmas farms to purchase a tree. Local farms offer the best freshly cut trees that should last 3 or more weeks inside your home. Trees for sale in urban lots may have been harvested  between 1-4 weeks earlier and shipped to your vicinity.

A cut Christmas tree should last longer if you choose one that’s fresh (branches are pliable and needles are not dried out). Keep the butt end of the trunk immersed in water until you are ready to bring the tree indoors for decorating.

Here are some tips in purchasing a tree:
1. Test for freshness by holding a branch between your thumb and fingers and pulling lightly toward you. If very few or no needles fall off, the tree is fresh. If the end of a branch bends easily, that’s also a sign of freshness. If you observe some yellowing, browning, or falling of interior needles, that’s okay. But, if you pick up a tree a few inches and slam it back down, lots of needles shouldn’t wind up on the ground.
2. Most tree lots will usually offer to cut the trunk of the tree for you. This allows for fast water uptake. You need to get the tree home and into water quickly.
3. If you’re not ready to take your cut tree indoors, set it in a bucket of water and keep it on a porch or in the garage—where it’s cool and sheltered from wind and sun.
4. Freshly cut 2-3 inch off the bottom (butt end) of the tree before bringing tree indoors.
5. Inside your home, tree will absorb nearly a gallon of water the first 24 hours. Thereafter, every 3-4 days, check and add water to the tree stand reservoir.
6.Keep cut trees (and all greenery) away from fireplaces and other heat sources.

Old-Fashioned Snake Plants

Snake Plant (Sanseviera)

Snake Plant (Sansevieria)

Snake plants

Snake plants in shady garden setting

Snake plant (Sansevieria spp.), aka Mother-In-Law’s Tongue, is an easy to grow succulent. It is one of the hardest house plants to kill, grows in almost any room of your home, and demands little attention except an occasional watering.

Its leathery sword-shape leaves are usually marked in gray green marbling. Some varieties may be edged in yellow or white. Plant varieties run from 6 inches to 4 feet in height and most are rosette form.

Snake plants tolerate low light, but grow better in bright light. They are not bothered when kept in a dark closet for 2-3 months. It grows well at room temperatures between 55 to 85 °F. Temperatures under 55 °F will mar some of the leaves. Rooms with low humidity don’t seem to bother plants. Misting foliage is unnecessary.

Water pots every 7 – 10 days thoroughly, allowing soil  (potting media) to dry in between waterings.  If leaves start to droop or the plant base begins to rot, you’re probably watering too much. If leaves appear wrinkled, you’re not watering enough. During the autumn and winter, reduce watering frequency to 2-3 times monthly. Prevent water from collecting in the tubular center of the plant.

Snake plants thrive outdoors in a shaded garden under a large shade tree in bright light. Add to containers with shade annuals and perennials. Plants grow vigorously and foliage coloration is more intense. Direct sun will burn the leaves of most varieties of Sansevierias.

Feed plants using a water soluble fertilizer such as Miracle-Gro® or Schultz® House Plant products. Use one-half the recommended package dose.

Repot snake plants every 12-18 months. If available, use a potting mix labeled for cacti and succulents, typically a blend of peat, bark, and coarse sand (or perlite).

White or cream colored lily-like flowers are highly fragrant and last 3-4 weeks. Flowers are attached to a long sturdy stalk and may be 3 feet high. What triggers flowering is unknown as it is a rare occurrence.

Poisonous!! Prevent pets and children from ingesting the foliage.

Christmas Vs Thanksgiving Cacti

Schlumbergia trucatum

Schlumbergera trucatum

1 year old plant from rooted cutting

2 year old plant from rooted cutting

Christmas cactus (Schlumbergera bridgesii) or Thanksgiving cacti (Schlumbergera truncata) are called holiday cacti. They are actually succulents and not true cacti. Both originate from tropical regions and make dependable, long-lived house plants.

Christmas cactus are frequently mislabeled as such and are really Thanksgiving cactus. Christmas cacti have flattened leaves with rounded leaf edges compared to Thanksgiving cactus that has pointed teeth.

Holiday cacti are short day plants. They bloom when night hours are 14 hours or longer and daylight hours are 8-10 hours long over 6 consecutive weeks. Bright outdoor lights or room lights may sometimes disrupt the dark period enough that they will not initiate floral buds. In such cases, plants may need to be covered (blackened) or moved into a closet each night.

An alternative method to induce flowering is to expose plants to cool 50-55°F temps. In warm areas in the Southern U.S. and other parts of the world, flowers may not form if night temperatures remain above 68°F regardless of daylength.

Holiday cacti should be repotted annually, preferably in February or March. Water only when potting soil feels dry or once weekly. Mist plants if the room humidity is low. Some flower buds may drop prematurely if room humidity is low or plant is open to cold air drafts. Ideal room temps are 70°F or higher daytime and 55 – 65°F at night. After threat of spring frost has ended, move holiday cacti outdoors into a partly shaded area. Continue to water and feed plants through the summer months.

Mix water soluble fertilizer products such as Miracle-Gro™, Hyponex™, or Espoma™ at one-half the package rate. Withhold winter feeding of plants until most flowers have dropped or restart in late February.

Mealy bugs and soft shell scales are potential problem pests. Overwatering leads to stem and root rots. Plant(s) may be pruned anytime for shaping. Old plants with dead or unattractive branches may be severely cutback after repotting in the spring. Such plants quickly recover.

Announcing AAS Ornamental Winners For 2017

"Profusion Red' zinnia (Photo from AAS)

“Profusion Red’ zinnia (Photo from AAS)

Geranium 'Medium Dark Red' (photo from AAS)

Geranium ‘Calliope Medium Dark Red’ (photo from AAS)

All American Selection (AAS) has named six Ornamental winners for 2017. Some include some new color breakthough in the series that you already know as well as some newbies.

Dianthus ‘Supra Pink’ (Hem Genetics) is an easy-to-grow interspecific dianthus for three-seasons (spring, summer, fall) of garden color. Its mottled, frilly pink flowers stand up to summer’s heat and drought. This vigorous, compact growing cultivar grows barely a foot tall covered with fancy, clear pink flowers. Also try sister cultivar ‘Supra Purple’, a 2006 AAS Winner.

Geranium ‘Calliope Medium Dark Red’ (Syngenta Flowers) has a deep red velvety flower color and great branching habit. All the Calliope® series of geraniums have been top garden performers. This interspecific hybrid has zonal-type flowers and leaves. It displays a mounded, semi-spreading growth habit and strong stems to support the showy flower heads loaded with deep red blossoms. It looks great in containers, hanging baskets and in-ground landscape and handles heat and drought conditions better than most annual geraniums (Pelagonium).

Penstemon ‘Twizzle Purple’ (Van Hemert & Co) is a hardy perennial (Zones 5 to 8) that exhibits vibrant purple blooms, a new and unique color in penstemons. Plant has an upright plant habit and superb flower numbers. The 1-inch tubular flowers form on long slender stalks that stand up to nearly 3 feet in height and are favorites for pollinators from mid- to late summer. Utilize this North American native in combination planters or in landscapes.

Verbena EnduraScape ‘Pink Bicolor’ (Ball FloraPlant) is the first verbena that can tolerate drought and heat plus survive temperatures down to the low teens. This long-blooming pink bicolor verbena is spectacular in a sunny garden, edging a walk or border or grown in large containers and hanging baskets. Vigorous plants spread with abundant soft pink blossoms with darker pink centers. Pink Bicolor is the newest color in the EnduraScape® series.

Vinca ‘Mega Bloom’ is an exciting new series of disease resistant vincas that are withstand summer heat and humidity. Orchid Halo produces huge bright rich purple blossoms with a wide white eye. Plants maintain a nice, dense habit with flowers standing prominently above the dark green shiny foliage. Note: annual vincas (Catharanthus roseus) are frequently called “periwinkles”.

Zinnia ‘Profusion Red’ (Sakata Seed) represents a breakthrough true red zinnia and a favorite of pollinators. The Profusion® series are recognized for their compact form, disease resistance, plus early and continuous blooms all season long. Its vibrant true red color won’t fade in the intense summer sun and heat.

Announcing The AAS 2017 Vegetable Winners

Chefs Choice Yellow Tomato (photo from AAS)

‘Chef’s Choice Yellow’ Tomato (photo from AAS)

'Antares' fennel

‘Antares’ fennel

For 2017 All-America Selections (AAS) has selected these winners in the vegetable category. Each is an outstanding garden performer compared to other varieties that it tested against. Three are national winners and one is a regional winner.

Fennel ‘Antares’ (Bejo Seed) is a national winner. AAS had never before trialed fennel previously. This beautiful plant has multiple uses: as an edible bulb; for its ornamental fronds; as a seed producer; and as a favorite food of pollinators, particularly swallowtail caterpillars. Antares fennel grows very uniform, pure white, and a much improved, almost sweet, licorice/anise flavor compared to other market varieties. It was also 7-10 days slower to bolt compared to other fennel varieties.

Pepper ‘Mad Hatter’ (PanAmerican Seed) is a national winner, chosen for the plant’s vigor, earliness, high yields, large size and fabulous sweet taste.  Mad Hatter has a novel three-sided shape. Fruits display a refreshing, citrusy floral flavor and are only occasionally mildly hot near the seeds. Plants grow vigorously with good yields in most areas of the U.S. and Canada. Add to salads raw, pickled or stuffed with cheese.

Tomato ‘Chef’s Choice Yellow’ (Seeds by Design) is a Southeast region winner, the fourth addition to the popular Chef’s Choice tomato series. It produces hearty beefsteak type tomatoes in a beautiful yellow color. Fruits are large and meaty with a sweet, citrus-like flavor, mildly acidic and a perfect tomato texture. The 10-ounce fruits grow on 5 foot high indeterminate vines that are resistant to fusarium wilt, verticillium wilt, mosiac virus, fruit cracking, and scab.

Tomato ‘Patio Choice Yellow’ (Seeds by Design) is a new compact, determinate tomato developed specifically for small garden spaces, including container gardens and hanging baskets. It produces very large yields of 1/2 ounce bright yellow cherry tomatoes on short vines that grow only 18 inches tall. Each compact plant produces over 100 fruits.

Fine Tuning Growing Calamondin Orange In The Home

Calamondin Orange(Variegated Leaf Form)

Calamondin Orange (Variegated Leaf Form)

Calamondin orange (Citris mitis) is challenging to grow in a home environment. It is hardy to 20°F., more than most other true citrus (USDA hardiness zone 8). It does not grow well in temperatures below 45ºF.

In temperate regions calamondin spends the active growing months (May – October) outdoors either in direct sunlight (in northern areas) and in half day shade (in south). Calamondin is moved indoors in winter into a well lit room.

New plants may be easily started from seeds or as rooted cuttings. Flowers are self-fertile and require no cross-pollination. A plant can be forced to flush new growth and bloom by withholding water. Once the leaves show symptoms of wilting, water the plant thoroughly. It should recover full of fragrant blooms within two months.

All citrus plants require iron supplement when soil pH creeps into the alkaline range. Iron becomes less available when soil becomes less acidic. A key symptom of iron deficiency is yellowing of the upper (newest) leaves. Twice yearly, use an iron supplement to maintain healthy green foliage. An alternative is to feed with a water-soluble acidic fertilizer such as Peters™ 20-10-20, Miracle-Gro™, or Schultz™.

Sticky or web-covered leaves may be signs of mite, mealy bugs, and scale infestations. Aphids and white fly may be problem pests in spring. Mealy bugs can be managed with insecticidal soaps inside the home. Otherwise, take the plant outdoors and spray with a pesticide labeled for controlling the specific insect on house plants.

Under optimum growing conditions, annual growth rate is 1 foot per year. Calamondin produces an abundant fruit crop starting at two years of age or when plants are at least 18-24 inches tall. Fruits are usually harvested in the fall.

Calamondin fruits have a thin, smooth, yellow to yellow-orange peel that is easily separable. Ripen fruits are very astringent, but make a tasty marmalade spread for your morning bagel or toast.

Facts About Garden Watering – How Much And When

Tripod rotating sprinkler over new lawn seeding

Tripod rotating sprinkler over new lawn seeding

Irrigation system

Irrigation system

Modern gardeners are using more efficient drip irrigation or soaker hoses. Water bills are less than overhead or oscillating systems.  You may opt to attach the hose to an automatic timer so you can irrigate in absentia. Water goes on and off anytime you select.

In garden beds water plants deeply once weekly rather than a little bit every day. During the summer months, daily or twice-daily watering may be needed for annuals and perennials growing in hanging baskets, window boxes. Newly planted and large container-grown small trees and shrubs may need a drink.

Over a dry summer, long season vegetables demand deep watering to yield tomatoes, squash, pumpkins, cucumbers, etal. Rhubarb, asparagus, and many perennial herbs need summer moisture to survive cold winters. In late fall rhododendrons, azaleas, blueberries, and other shallow rooted plants should be deeply irrigated before heading into a dry cold winter.

How much water do garden plants require? Most summer annuals need an inch of water weekly—either supplied by natural rainfall or through a hose.  Never waste water, no matter how full your city’s reservoir supply; don’t send water down the driveway or street gutter. Mulching plants aids to lower water use.

By mid-July, plants growing in containers require almost daily watering. Some container grown plants like daphnes or hostas are not forgiving if you miss a scheduled waterings, while agaves don’t seem to care. Bigleaf hydrangeas (Hydrangea macrophylla) or ligularias may be seen wilting in the mid-day sun, but fully recover by evening. Repotting plants into larger containers also helps.

Early morning is the best time to water by hand or by an oscillating sprinkler. Plant foliage has adequate time to dry off, reducing potential problems with fungal and bacterial diseases. Disease causing spores require moisture on the leaf surfaces. Snail and slug injury is worse by irrigating in late day or at night.

Finally, the more that you irrigate, nutrients, particularly nitrogen, are leached out of the root zone. New fertilizer must be applied for plants to continue growing and not suffer from nutrient deficiencies. Overwatering leads to root and crown rot problems.

Japanese Larch Is Preferred In Northern U.S.

Larix kaempferi 'Wolterdingen' at Chicago Botanical Gardens

Larix kaempferi ‘Wolterdingen’ at Chicago Botanical Gardens

Larix decidua at Biltmore Estates, Asheville, NC

Larix decidua at Biltmore Estates, Asheville, NC

Larches (Larix spp.) are majestic deciduous conifers in their northern ranges of their habitat (USDA hardiness zone 4 to 7). However, trees do not prosper in hot and humid summers south of USDA Zone 7.

One of the best is Japanese larch (Larix kaempferi), but unfortunately, it is not commonly planted in U.S. landscapes. The tree averages 50-60 feet in height and 25-35 feet in width. Old specimen trees that are 70-90 feet tall are not difficult to find in botanical gardens in zones 5 and 6.

The tree grows rapidly with an open and pyramidal form and slender, pendulous branchlets. Its fine textured needles are soft to the touch. Bright green needles (to 1 ½ inches long) appear in brush-like clusters at the ends of spur-like shoots along the branches. In autumn needles turn golden yellow and dust the ground around the tree as fine mulch. Flowers appear in March, and the seed bearing cones ripen in October. Also, the 1 ½ inch long green cones feature reflexed bracts that turn brown at maturity.

Japanese larch prefers a fully open site. Soil should be mildly acidic and adequately drained. Larch is intolerant of poorly drained or dry soils, deep shade, and most urban pollutants. Japanese larch is preferred over European larch (L. decidua) because the latter is susceptible to numerous diseases and pests, particularly needle cast, needle rust, canker, and case borer.

Its enormous tree size makes it more suited for large properties such as parks and golf courses. Larch may be planted for reforestation, as a windbreak, or as an individual specimen.

Cultivars: ‘Pendula’ is a popular weeping form in the U.S. ‘Diana’ has contorted, twisted branches; it grows to 6-8 feet tall over the first 10 years, maturing to 20-25 feet high. ‘Wolterdingen’ is a slow growing dwarf shrub and very popular among dwarf conifer collectors.