Bougainvillea

Bougainvillea is the stuff of dreams—a showy vine covered with glamorous spots of colour—especially if you’re shovelling snow or bailing out floodwater. This South American vine goes hand in hand with sun-drenched courtyards and dusty desert sunsets; its colourful, frilly bracts shout Latin romance as clearly as a flamenco dancer’s skirts. Gardeners in colder climates must carefully plan their affair with this exotic dreamweaver: The liaison will commence in spring and end with the first chilly days of fall unless there’s a greenhouse involved. In warmer zones, though, bougainvillea is a vigorous evergreen climber—given enough time, it will cover your wall, your trellis, and maybe your roof with its bright-hot blooms.

Common name: Bougainvillea

Botanical name: Bougainvillea
Plant type: Evergreen or semi-evergreen vine or shrub
Zones: 9 to 11; grown as annual in colder zones
Height: 15 to 40 feet
Family: Nyctaginaceae

Growing conditions

· Sun: Full sun
· Soil: Acidic, well-drained
· Moisture: Average to dry; drought-tolerant once established.

Care

· Mulch: Mulch to preserve moisture in the soil.
· Pruning: May need trimming to keep its shape; prune after flowering.
· Fertiliser: During the growing season, fertilise every two weeks.

Propagation

· By cuttings or layering (bury a low branch in the ground, where it will develop a set of roots).

Pests and diseases

· Aphids, scales, whiteflies, spider mites
· Leaf spots

Garden notes

· The papery, brightly coloured “flowers” of bougainvillea are technically bracts—the actual flowers are on small upright stems in the centre of each bract.
· In climates where bougainvillea is hardy, train it along a trellis or over a pergola. In colder zones, plant it in containers or in a greenhouse.

· Many bougainvilleas have long, sharp thorns, so plant them away from high-traffic areas and be careful when pruning.
· If you grow a bougainvillea in a greenhouse or indoors, be sure to give it plenty of room.

Cultivars

· Bougainvillea ‘Barbara Karst’, B. ‘Double Red’, and B. ‘Scarlett O’Hara’ (pictured) have bright red bracts.
· B. ‘Double White’ and B. glabra ‘Snow White’ have white bracts.
· B. ‘Blueberry Ice’ and B. ‘Raspberry Ice’ have variegated leaves.
· B. ‘California Gold’ has deep golden-yellow bracts.

All in the family

· Another familiar garden plant in Nyctaginaceae is the garden four o’clock (Mirabilis jalapa). There are about 290 other species in the family, concentrated mainly in tropical and subtropical areas.
· Other Bougainvillea species popular in the garden include B. x buttiana and B. spectabilis.

Flower reproduction

When it comes to reproduction, the birds and the bees certainly have a less complicated time of it than plants do. Did you know that whether or not a plant will bear fruit or seeds is an incredibly complex process, tied to the sex of the plant? That’s why some plants need a similar type of plant growing near them in order to produce desirable fruit. For example, some plants produce only male or female flowers; to produce seeds, both male and female flowers are needed. The following terms may help you understand some of the intricate aspects of plant reproduction.

Perfect flowers

These flowers have both male and female reproductive organs, meaning they can produce both pollen and seeds. The male organs, known as stamens, produce pollen. The female organs, known as pistils, contain ovaries that will eventually hold seeds if the flower is pollinated. A perfect flower can often pollinate itself if the pollen from the stamen falls onto the pistil or is brushed there by a visiting bee or other insect. Most common flowers, including African violets, roses, daffodils, potatoes, strawberries, and pears produce perfect flowers.

Imperfect flowers

Sometimes a flower contains only male or female organs, so we call that a male or female flower. Since these flowers lack the full set of parts, they are considered “imperfect,” and as such, cannot be self-pollinating. A bee or other insect must travel from a male flower to a separate, female flower either elsewhere on that same plant or on a nearby plant in order for there to be seeds or fruits. Plants with imperfect flowers include squash, walnut, birch, and many begonias.

Polygamous

Some plants can have both perfect and imperfect flowers at the same time. One flower may have both male and female parts, while another flower on the same plant has only male or female parts. These plants can produce their own fruits, but they usually produce more fruits if there is also a similar plant growing nearby to act as a pollinator. (Bees and other insects transfer the pollen from one plant to another on their body.) Some maples (Acer spp.) and smokebush (Cotinus spp.) are polygamous.

Dioecious

To add another level of complexity to the confusing business of plant sex, some plants themselves are either female or male in that they have only male or female flowers. These are the plants that must be planted in pairs or other multiples containing at least one male and one female in order to produce fruit or seeds. If you don’t want your plant to produce seeds or fruit, look for male plants. Any good nursery or garden center should be able to help you find these.

Dioecious plants include many hollies, ginkgo (Ginkgo biloba), asparagus, and willows. For many types of holly to produce their fruits, pollinator male plants such as ‘Blue Boy’ or ‘Jersey Knight’ must be planted near the female plants. Because they act as pollinators, these male plants cannot bear their own fruits. Knowing the sex of some plants is handy in other ways: Many gardeners and landscapers avoid planting female ginkgo trees, for instance, because the fruits emit a bad smell.

Helenium

Warm rust, rich yellow, and burnt orange flowers top the tall, slim stems of sneezeweed (Helenium spp.) from late summer to the first frost.

A native perennial at home in a prairie garden, it’s also found along streams, ponds, and moist meadowlands throughout North America. Most sneezeweeds reach 3 to 5 feet, so they fit well in the back of the garden, providing rich autumn colour for several weeks. Pair sneezeweeds with blue asters, Russian sage, and golden mums for a lovely fall garden.

Plant Facts

Common name: Sneezeweed
Botanical name: Helenium spp.
Height: 24 to 60 inches, depending on cultivar
Plant type: Clump-forming annual or perennial
Zones: 3 to 8, depending on cultivar
Family: Asteraceae

Growing conditions

Sun: Full sun
Soil: Well-drained to heavy soil
Moisture: Medium to wet

Care

Mulch: Put down a 2- to 3-inch layer of organic mulch to conserve moisture, keep roots cool, and suppress weeds. Apply winter mulch after soil is frozen.
Fertiliser: Not necessary in average soil. Over-fertilisation and very rich soil cause rangy, weak growth.
Pruning: Pinch back in early summer to create healthier foliage and sturdy branching. Remove spent flowers to encourage more flowering.

Species and Cultivars

Helenium flexuosum (pictured) has yellow, wedge-shaped, drooping rays and purple-brown disks. It blooms August to October and prefers moist sites near meadows and roadsides. Commonly known as a purple-headed sneezeweed, it grows 1 to 3 feet tall. Zones 5 to 9.
H. autumnale has yellow flower rays from late summer to fall. Grows 5 feet tall. Zones 3 to 8.
H. ‘Butterpat’ has deep yellow flowers and grows 3 feet tall. Zones 4 to 8.
H. hoopesii has grey-green foliage and 3-inch flowers with yellow rays and orange centres. Blooms earlier in summer than other sneezeweeds. Grows 3 to 4 feet tall. Zones 3 to 8.
H. ‘Moerheim Beauty’ bears 2- to 3-inches flowers with copper-red florets and brown disks from early to late summer. Has sturdier stems than other sneezeweeds, so it usually doesn’t need staking. Grows 3 feet tall. Zones 4 to 8.

Garden notes

Though its common name is sneezeweed, it doesn’t cause hay fever.
Divide every three to four years for good flower production.
Good companions for sneezeweed include goldenrod, yarrow, sunflowers, and ‘Autumn Joy’ sedum.
Attracts honeybees and butterflies.

Pests and diseases

Powdery mildew, rust, and fungal spots occur occasionally.

Propagation

Sow seeds of the species in spring. Don’t sow seeds of cultivars, as the offspring won’t be the same as the parent plant.
Take cuttings of cultivars in spring for rooting in a cold frame.
Divide plants in spring or fall.

All in the family

The Asteraceae (once called Compositae) family is also called the daisy, sunflower, or aster family.
Many are excellent nectar producers for honeybees. Sunflower (Helianthus annuus) and some goldenrod (Solidago) plants are important “honey plants” for bee keepers.
Botanists describe most members of the Asteraceae family as having flower heads rather than flowers. They have one or both of these structures: ray florets (the petals) and disc florets (the centre disc that’s composed of tiny tubular flowers). Dandelions have just rays, and sneezeweeds have both ray and disc florets.

Pollen and how to pollenate

Pollen production can be a real pain, but for gardeners, an abundance of healthy, ripe pollen is the rich vein of gold that produces our most popular food crops, from apples and cucumbers to tomatoes and corn. Without pollination, most plant and animal life in our gardens—and on our planet—would cease to exist.

Pollens are as distinct as the plants on which they’re found. Tiny, dry, wind-transferred pollen types (such as corn and ragweed) are the bane of hay-fever sufferers. Larger, sticky, insect-transferred varieties (such as fruit and squash) come on showy, scented flowers designed to attract pollinators.

Pollen grains develop at the heart of blossoms in structures called anthers, atop stalklike stamens. As pollen ripens, the anthers open. Wind or insects transfer the pollen grains, which contain male reproductive cells, to the tips of pistils, the female parts of blossoms. There the pollen germinates (much like a seed does), each grain sending a tube down into a pistil to the flower’s ovary, where it fertilises a seed-producing ovule.

To generate a bumper crop of almost anything in a growing season, this chancy process must take place hundreds, thousands, even millions of times.

The life span of a pollen grain is fairly short, ranging from a few hours to a few days. To improve the odds that at least some ripe pollen will land on desirable pistils, plants produce vast volumes of the stuff—at least, that’s the game plan. But a lot can go wrong along the way.

Soil nutrients, moisture levels, weather, and sunlight all influence pollen production. Temperature is crucial—the ideal pollen-germinating temperature for most plants is 65ºF to 75ºF. Germination generally slows or grinds to a halt when nights drop below 60ºF, days are above 85ºF, or humidity tops 70 percent. Though airborne pollen usually peaks between 5:00 a.m. and 10:00 a.m., pollen production can be eccentric. For instance, some varieties of avocado shed pollen in the morning and receive it in the afternoon, while others do the opposite.

You can help maximise pollen production and germination in your garden by taking a few simple measures:

Test your garden soil regularly. Plants need balanced nitrogen, phosphorous, and potassium levels for blossom production, and they require adequate levels of calcium and boron for healthy pollen development. Uptake of these vital nutrients suffers if soil pH is lower than 5.5 or higher than 7.5. (Most garden plants grow best when the soil PH is between 6.0 and 7.0.)

Select plants suited to your climate. In hot-summer regions, plants such as muskmelons and tomatoes stop ripening pollen in July and August. Early-blooming varieties, such as Early Goliath tomatoes, are a good bet in these regions—they ripen enough pollen to produce good crops before temperatures become too hot.

In short-summer regions, cool spring temperatures delay pollen development until it’s too late for long-season crops to mature. Try early-maturing varieties, such as Park’s Whopper Hybrid cantaloupe, in these regions—they ripen within a relatively narrow window of opportunity.

Maintain even soil moisture. Water helps plants take in the nutrients that encourage blossom development, so drought conditions can dramatically reduce pollen production. Make sure pollen-producing plants have a consistent amount of water, but avoid top-watering, which washes delicate pollen off flowers and out of the air.