Saturday, March 26, 2016

Big, Bold Bougainvilleas

No matter where ever you go in the tropic's you'll always come across the vibrant sun loving presents of Bougainvillea's.   These drought tolerant sprawling climbers will thrive under neglect to shower you in a massively floriferous display of color throughout spring, summer or autumn.  Their resilience and color have gained them a place in many tropical gardens around the world.

Bougainvillea's were first discovered by a french naval commander, Louis-Antonie de Bougainville around the coastal areas of Rio de Janeiro, Brazil between 1766-1769.  By the early 19th century, Bougainvillea's had made their way to the nurseries of Europe where a thriving trade soon grew.  It was shortly discovered thereafter that the species naturally hybridized with colorful hybrids popping up spontaneously wherever Bougainvillea were grown.

Bougainvillea's comes from the Nyctaginaceae (Four-o-Clock) family which hosts 33 different related genera.  Within the genera Bougainvillea genera, there are 14 species, with only three that are considered horticulturally important; B. spectacles, B. glabra and B. peruviana.  They are a tropical to subtropical woody evergreen, shrubby vine typically with multi-trunked or clumping stems.  Left naturally, it has a spreading habit and forms a rounded plant with a height and spread of up to 20 feet.  However, with training the eventual size often is much greater.

The true flower is a small, tubular, white to yellow bloom that is surrounded by the brilliantly colored bracts, or modified leaves.  The same flower modification can be seen in Dogwoods and Poinsettias where the true flower is often over shadowed by the vibrantly colored bracts that surround it.  They come in various different colors from lilacs, oranges to yellows, pinks, purples, reds, violets and whites with various shades in-between.   Double braced forms and variegated foliage hybrids can be found for those looking for a little more interest.

Location: Bougainvilleas will grow best in full blazing sun or with at least 5 hours of direct afternoon light per day.  Not enough sun = not enough bloom.  They thrive best in outdoors in areas of low rainfall and intense heat with night temperatures that are above 60 degrees F.  This makes them ideal for year round cultivation in US hardiness zones of 9 and higher.  However, they can be grown during the summer months in colder zones as long as they are brought inside and protected from freezing weather.  Although a tough and durable plant, they don't tolerate strong prevailing winds.  It is best to secure your plants so they get shelter from high winds and don't rock around.

Feeding: Although Bougainvilleas grow like brutes in the garden, they are big babies when it comes to their roots.  They have delicate, thin roots which will easily burn if too much fertilizer to applied all at once.   The best approach to feeding is to apply the fertilizer weakly but with multiple applications out over a longer period.  A balanced, slow released fertilizer high in iron to prevent chlorosis, and plenty of micronutrients is all that is needed.  Liquid feeding with soluble fertilizer is also a good option but requires increased frequency of applications to achieve the desired results. They are heavy feeders during their flowering season and will benefit from a increase in feeding.  However, during  non-flowering periods the feeding can be reduced.  Fertilizer should never be applied to dry soil as this will burn their delicate feeder roots.

Soil and Watering: Bougainvilleas grow best when planted in a well draining loamy soil mixed with good amounts of organic matter to help nutrients and oxygen get down to those delicate roots.  A soil pH range of 5 to 7 is ideal.  Deep watering is always preferred as long as the soil drains with little trouble.  Once established, they're drought tolerant and prefer to on the dry side.  By keeping your plant a little under stress you'll improve the flowering show.

Planting or Re-potting:  As mentioned during the section on feeding, Boug's are big babies when it comes to root sensitivity.  When planting, try and not disturb the roots as you move the plant from its nursery pot to the final home.  Careless planting can send these plants into serious shock or in the worse case will lead the plant to die.  As such, many people chose to plant them with the nursery pot still on, but cut away the bottom to allow for the roots to push out and explore their new surroundings.  If growing in a container, Boug's love to be pot bound and should only be stepped up a single size without breaking of fiddling with the rootball.  Root pruning is not recommended.

Training and pruning: Bougainvilleas are extremely vigorous growers and don't mind a good whacking back to set their shape.  Start by training selected stems to make a good framework of branches and create a desired form.  Boug's don't have a natural ability to cling or attach themselves to structures so you will need to fasten them if you wish for it to climb.  Once the shape is achieved, lighter prunings after each flowering cycle and removal of water shoots is all that is need to keep the plant in check.  It is best to remove side shoots to about 2 inches from the old cane (just like climbing roses) to produce flowering spurs and maintain its shape. Bougainvilleas bloom in new wood. The more you pinch out and trim, the more flowers you'll encourage.


Growing in containers:  Of course not everyone has the space to allow these super-sized beast to take over or have the growing climate for it to live outside year round.  Fortunately, Bougainvilleas response well to container culture and actual prefers their roots to be a bit snug in a pot.  Start by using a container one size up from its nursery pot and use a planting mix moderate in peat moss with plenty of drainage.  Peat moss can retain to much moisture and may result in root rot issues.  Water soluble fertilizer is the best approach to feeding Bougainvilleas in pots with a application of slow release granular fertilizer given when potting on.  Also, consider some of the smaller cultivars (some of them thornless) like Helen Johnson, Flame, Silhouette, Miss Alice or the Ice series.  Click here for a chart of recommended cultivars.

Pest and diseases: Bougainvilleas are fairly free of trouble.  For the most part, the usual culprits that cause damage are Aphids, Caterpillars (loopers), grasshoppers, mealybugs, mites and whiteflies.  Using a good wide spectrum insecticide at the first sign of damage will halt any problem from getting out of hand.  For diseases, leaf spots and root rots will be more of an issue on heavier soils or places where irrigation is frequently wetting the foliage.  Broad spectrum fungicides will help prevent the spread but a change in water management will reduced the problem over the longterm.

One common physiological problem faced by anyone growing Bougainvilleas is chlorosis, a lack of normal green pigmentation in the foliage.  This is often cause by a deficiency of iron or magnesium or a high soil pH that prevents the uptake of these nutrients into the plant.  Mixing 1-2 teaspoons of Epsom salts with 1 gallon of water and applying with a watering can will improve the situation.  Also, acidifying the soil with aluminum sulfate, chelated iron or elemental sulfur with help with the plants absorption of these elements.  If after this your plants systems don't improve, you could be seeing the effects of water logging or a nematode issue affecting those delicate feeder roots, where a change in cultivation will be needed to reverse the symptoms.

From vines, ground covers, hedges, containers, topiaries and bonsai, there is a Bougainvillea to fill you needs.  With very little needs, Bougainvilleas will provide eye-catching color over long periods in the garden.  Even if you don't live in the tropics, they adapt well to overwintering inside a house to provide a colorful display during the summer months.  So, isn't it time you planted a Bougainvillea for your garden?


For more information on Bougainvilleas follow these links: