News from Hidden Valley Hibiscus
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Greetings to all hibiscus enthusiasts!
Despite the fact that winter is rapidly approaching, many of us are still enjoying the fall flower show put on by our hibiscus. Those living in more northerly areas have moved their hibiscus to protected locations, such as indoors where sunny windows are still bringing forth flowers. Yet there is a mystery with many of the flowers - their colors have changed. What's going on here? We explore this fascinating subject in the featured article below that explains The Mystery of Hibiscus Colors.
Each month the HVH Newsletter goes out to many thousands of hibiscus enthusiasts around the world - some are experienced experts but many are relatively new to the pleasures of hibiscus gardening. All of us were "newbies" at some point and we all needed to learn a few terms that are commonly used in the hibiscus world. Do you know the difference between species and hybrids, grafted vs. own-root plants, or garden variety vs exotic hibiscus? Our second article this month clears up any confusion about these terms with some examples and excellent photos.
Don't forget to scroll down to our November Seedling of the Month, 'Winter Lights,' our newest blue hibiscus.
Happy reading, happy Thanksgiving, and happy gardening!
Charles and Cindy Black
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'Heavy Metal' in Heat
Anthocyanins Burn off, leaving White Spots under Red.
Carotenoids Increase, turning Edges Bright Yellow.
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The Mystery of Hibiscus Colors
Why do hibiscus flowers change color?
One of the most fascinating, albeit frustrating, characteristics of hibiscus is the way the flower colors change. A few hibiscus produce the same colors at all times of year in every kind of weather. But the vast majority of hibiscus change their colors with changes in temperature, hours of daylight, and who-knows-how-many other variables! In this article we will explain at least some of the color changes that hibiscus go through.
'Heavy Metal' in Winter
Anthocyanins Increase, Turning Flower Solid Red.
Carotenoids Decrease, Softening Edges to Orange.
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Hibiscus flower colors, like the colors of most flowers and fruits, are made up of three basic pigment groups: carotenoids and two types of flavanoids - anthocyanins and flavonols. While the study of flower pigmentation can be very complex (and confusing!), some fairly simple principles emerge that we can apply to growing our own hibiscus.
Carotenoids ~ The Yellow, Orange, Red Spectrum
'Gold Mine' in Winter
Cold Weather Decreases Carotenoids.
Flower Opens and Stays a Soft Orange
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Carotenoids - think carrots, pumpkins, corn, yellow squash. Beta-carotene, lycopene, zeaxanthin, and violaxanthin are examples of the carotenoid pigments, and yes, these are the same carotenes we take in our daily vitamins! This is one of the reasons why hibiscus are being studied for their human health benefits.
Carotenoids Hold their Color
'Gold Mine' in High Heat
Carotenoids Increase
Making Vivid Red & Yellow
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Carotenoids are the most stable of the flower and fruit pigments. They are enclosed in their own little compartments, called "plastids," nestled inside the cytoplasm of individual plant cells, out of reach of many of the substances that a plant absorbs. Pesticides don't reach them, nor do most of the nutrients and toxins plants absorb from the soil or air. When damaging substances do manage to get to them, these carotenoids have a second line of defense in their anti-oxidant actions that protect the plant even further. So the carotenoid pigments last and last. Whatever color the flower opens with, it maintains that color until well after it folds back up. We see this in hibiscus. Our bright yellow and orange flowers tend to hold their color, even through the hottest summer days.
Hot Weather Increases Carotenoids
'Saffron' an Example of a Bloom
With High Levels of Carotenoids
Making our Most Vivid Orange
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With all pigments, the more pigment the flower produces in the bud, the brighter its colors will be. With carotenoids, a little bit of pigment makes a soft yellow flower. As the pigment levels increase, flowers become increasingly vivid yellows, oranges, and reds. This is the progression that a tomato follows as it ripens, gradually increasing production of carotenoids until it is fully ripe and red. Carotenoids increase production in response to heat and lots of sun. The hotter and sunnier the weather gets, the more carotenoids a plant produces, the brighter the oranges and reds will get. When weather cools off, carotenoid production decreases, and colors become softer oranges and yellows.
It works the same with hibiscus. The hotter it gets, the brighter the orange and yellow flowers get. 'Gold Mine' and 'Saffron' are good examples. In hot, sunny, summertime heat, 'Saffron' blooms with vivid orange flowers, and 'Gold Mine' is bright red with vivid yellow markings. In cool cloudy weather, both these hibiscus bloom with paler orange or even golden-colored flowers, and 'Gold Mine' loses its yellow markings completely.
'Sleeping Beauty' in Cool Weather
Anthocyanins & Flavanols Increase
Making an Array of Beautiful Colors
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Anthocyanins ~ The Blue, Purple, Pink, Red, Black Spectrum
Anthocyanins are best known as the red pigment in fall leaves. We all know that fall leaves change color in response to weather conditions, and this is the hallmark of anthocyanin pigments. Anthocyanins are plentiful in hibiscus, giving the flowers their many showy bands of color, as well as their tendency to bloom with different colors depending on many different variables.
'Sleeping Beauty' in Warm Weather
Anthocyanins & Flavanols Decrease
Decreasing Color Bands
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Anthocyanins are Unstable
Anthocyanins are a much different kind of pigment. They are much less stable than carotenoids. Anthocyanins aren't safely enclosed in plant cells. They are created in the roots, dissolved in the water that makes up plant sap, and move all the way up the plant to where the flowers develop. The least little change in the environment or health of the plant affects the sap, which means it also affects the anthocyanins. This is why blues and purples tend to be so changeable in hibiscus flowers - they are produced by the notoriously unstable anthocyanin pigments.
'Sleeping Beauty' in 2nd Day of Heat
Anthocyanins & Flavanols Burn Away
Colors Fade Almost Completely
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A single anthocyanin pigment can be deep blue or deep red or anything in between, depending on many different variables. One variable we understand to some extent is ph. The levels of alkalinity and acidity in flowers change the color of anthocyanins from the blue ranges to the red ranges. Gardeners use this knowledge to change the colors of hydrangeas between pinks and blues by changing the soil ph. This means we should be able to predictably change the color of a hibiscus flower by changing the plant's ph then, right? Don't we wish! Many of us have tried this, but unfortunately, ph in hibiscus is dictated almost entirely by genes. Within a single flower, there will be pockets of pigment with different ph levels, creating different colors from the same anthocyanin pigment.
'High Voltage' in High Heat is White
Red Anthocyanins Burn Away in Heat
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Anthocyanins Increase and Turn Red in Response to Cold
Nature does do some things that alter ph and other anthocyanin characteristics of plants though. Anthocyanins function as a sort of anti-freeze chemical in plant sap. In response to dropping temperatures, plants produce more anthocyanins, and the anthocyanins become redder. For some reason, redder anthocyanins seem to have a more protective anti-freeze effect in plants. This happens in maple leaves, and it's the same mechanism in hibiscus flowers. Dry weather increases this darkening and reddening effect even more, as we see sometimes when mid-summer drought causes tree leaves to develop fall colors early. But it does take a certain amount of sunlight to create anthocyanins, so fall weather, with bright sunny days, less rain, and cold nights, is the perfect weather to maximize anothocyanins, to turn leaves their brightest reds and oranges, and to increase and darken the reds and pinks in hibiscus flowers.
'High Voltage' is Pink in Winter
Red Anthocyanins Increase in Cold
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'High Voltage' is a good example of this effect. In the hottest summer, the flower is almost pure white, with just a hint of pink blush from anthocyanins. As fall weather cools the nights, anthocyanins increase, and the pink blush starts to deepen and spread. In the coldest weather, the whole flower fills with anthocyanins and turns almost completely pink. In mid-winter here in Southern California where hibiscus keep blooming until Christmas, the December flowers can all be so red and pink that at times we have difficulty identifying them.
Anthocyanins Degrade and Disappear with Heat
Some anthocyanins are very sensitive to heat. Enzymes in plant sap completely destroy several of the anthocyanins in hot weather and bright sunlight, and this creates the fading effect we see in so many hibiscus flowers in summer heat. These are the hibiscus that we recommend keeping in partial shade during the heat of the summer, like 'Sleeping Beauty.' Its anthocyanin pigments are beautiful in the cooler, cloudier times of year, showing a rainbow array of 5 different bands of color, and holding the color well. In summer heat though, the flowers have only 2-3 colors, and in bright sunlight, these colors fade very quickly. But a 'Sleeping Beauty' growing inside a house in a window that gets an hour or two of sun every day will bloom with a full array of colors that will last for 2-3 days. Inside a house, or in partial shade, the anthocyanins are protected from too much heat and sunlight.
Anthocyanins Increase Production and Show a Wider Range of Colors with Maximum Nutrition
'Blue Ballerina' with Good Nutrition
Anthocyanin Pigments Develop Best with Optimum Nutrition
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Anthocyanins are produced in sap by a reaction between sugar, or
brix, and protein. Higher sugar or brix content in the sap and an ability to produce proteins plentifully are both requirements for a plant to produce maximum levels of anthocyanins. Although horticulturists keep looking for tricks to increase brix production in food plants, the most sensible and easiest way is to maximize your plants health in every possible way. Extra good soil, extra good nutrition, extra good care will, over time, increase both sugar and protein production, and you will see the difference in your flower colors.
Some hibiscus are very, very sensitive to this nutritional effect, and will even stop producing flowers all together if the sugar and protein levels in the sap gets too low. Others will produce flowers, but the colors will be pale, or some colors will be missing. The health of the plant really does matter when the colors depend on anthocyanin pigments!
Flavonols ~ Pale Yellow, White Spectrum
'Acadian Spring' Opens with Soft Yellow Edges
Produced by Flavonols
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Flavonols are in the flavanoid family with anthocyanins, and have all the same characteristics of anthocyanins - they degrade in heat and lots of bright light, and they increase in a healthy plant and in cold weather. But flavonols have their own distinctive pale yellow color veering into white. The yellow edge of 'Sleeping Beauty' is produced by flavanols, and increases and decreases in response to the same conditions that increase and decrease it anthocyanin blues and pinks.
'Acadian Spring' is a good example of a hibiscus flower that uses flavanols exclusively. It opens with a soft yellow flower that fades in sunlight and heat to almost pure white. In cooler weather, 'Acadian Spring' flowers open almost completely yellow and they don't turn white during the day.
'Acadian Spring' in Afternoon Sun
Flavonols Degrade in Sun and Edges Fade
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Now you know everything there is to know about hibiscus pigments. Well, not exactly.... It's a pretty complex field of study, and you probably know more now than you ever wanted to know. But as you watch your blue hibiscus flowers turn pink, your pink flowers turn red, and your orange flowers turn yellow this fall, you'll at least have some idea of how and why this happens.
Exotic, Tropical, Fancy, Hardy, Hybrid, Species, Perennial, or Garden Variety!
What Kind of Hibiscus are These?
At HVH we grow Exotic, Tropical Hybrid Hibiscus.
What does this mean????
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People ask us constantly what type of hibiscus we grow. The answer is simple: At HVH we grow
exotic, tropical, hybrid hibiscus. What?????? What the heck does that mean? Let's see if we can answer this question....
Hibiscus are a confusing group of plants! We get a lot of email all the time asking questions about the different types of hibiscus, and unfortunately for all of us, there aren't really uniform, standardized names for any of the different kinds of hibiscus. Each new type has unofficial names that have cropped up among growers and aficionados, and different groups of people use different names for the same plant, or the same name for different plants. Does this all sound confusing? Well, it should! It confuses everyone in the hibiscus world! We hope this article will help sort out some of the terminology and types of hibiscus that we find in gardens around the world.
Tropical Hibiscus v. Hardy or Perennial Hibiscus
'Acapulco Gold' Like all HVH Hibiscus
Is a Tropical Hibiscus |
The two main groups of hibiscus that we most commonly grow in our gardens are
tropical hibiscus and
hardy,
winter-hardy or
perennial hibiscus. Tropical hibiscus, as the name describes, originated in tropical climates, stay green year-round, and do not tolerate freezing temperatures. These hibiscus are all descendants of the tropical species
Hibiscus rosa-sinensis mixed with seven other species of tropical hibiscus. Tropical hibiscus can only live outside year-round in warm climates where it seldom freezes, and when it does freeze, the cold spell is mild and very short. These are the hibiscus that we associate with Hawaii - the kind that are strung into Hawaiian leis, for example. All our hibiscus at HVH are tropical hibiscus, so northerners have to find ways to winter them in warm places. They have a very long blooming season, from spring through late fall, and into winter in places where it doesn't freeze. They shed a few leaves at a time all year round, so although they do shed all their leaves each year, it's not noticeable, because they are covered with green leaves all the time.
Hardy hibiscus, also called "winter-hardy" or "perennial" hibiscus, are most often descended from the species Hibiscus moscheutos or "Rose Mallow", and sometimes from the species Hibiscus mutabilis or Hibiscus coccineus. Some of the ancestors of these hibiscus were native to the Americas, and all were native to colder parts of the world. Hardy hibiscus die back all the way to the ground each winter, and shoot up new growth each spring. These hibiscus grow well in cold climates, but don't grow as well in warmer climates, especially hot, dry climates. Hardy hibiscus bloom in late summer or early fall and have a shorter blooming season than tropical hibiscus. At HVH we don't grow any of the hardy hibiscus. We have tried in the past, but they don't grow well in our hot, dry California climate.
Hybrid Hibiscus v. Species Hibiscus
Hybrid Hibiscus
'Key Largo'
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These terms can be applied to almost every type of hibiscus. When we use them at HVH, we are applying them to our tropical hibiscus. But growers of hardy hibiscus use these terms too, as do all growers of all types of "hybridized" flowers - which means most of the flowers growing in our gardens in modern times. Hybridizing is simply crossing different species or different varieties to produce new varieties. Most types of flowers can be hybridized, and almost all the hibiscus we grow today are hybrids.
At HVH we hybridize our own new hibiscus varieties, or cultivars on a continuous basis, and each year we offer the best of our new hybrids for sale. It takes a lot of hybridizing to produce a few good hibiscus varieties. Typically, for each hundred new crosses we grow and test, only about two of the new cultivars are good enough to make it to market.
Species Hibiscus
Hibiscus rosa-sinensis
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The only hibiscus that aren't hybrids are the original wild
species hibiscus that originally grew in the tropics of Asia and islands off of Africa. Species plants, by definition, can self-pollinate and make seeds that will reproduce the same exact plant and flower. If a hybrid hibiscus produces seeds, each seed will produce a completely different hibiscus with an unknown flower, so hybrid hibiscus varieties can't be reproduced from seed. Only species hibiscus can.
For more information about the different hibiscus species that combined to create the modern hibiscus hybrids, see the Hibiscus History article on our website. We do grow and sell some of the species hibiscus at HVH. You can find them on the Ancestors Page of our Online Store.
Garden Variety Hibiscus v. Exotic Hibiscus
Garden Variety Hibiscus,
Lots of small simple flowers
with lots of foliage on a large bush.
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These are relatively new names in the hibiscus world. Garden variety hibiscus are the ones we are all familiar with from our childhood - the simple hibiscus flowers on large bushes that grew as high as our houses. These are the hibiscus that leis are made from in Hawaii, for example. Garden variety hibiscus are all hybrids, like almost all the hibiscus we are familiar with. But garden variety hybrids are simpler, older hybrids. They usually come in only a single solid color, or possibly a mix of two colors. The flowers are small - mostly the size we now call "mini."
Exotic Hibiscus,
Fewer bigger, more complex flowers
with less foliage on small bushes.
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The new, large, wildly colored, crazily different hibiscus that we grow at HVH are what we call
exotic hibiscus. In some areas they are also called
fancy hibiscus. Their bushes usually don't grow as big or as vigorously as garden variety hibiscus, but the flowers are much more spectacular. Exotic hibiscus are all tropical hybrids that must be protected from freezes in the winter. Producing such large multi-colored flowers requires good nutrition and some tender loving care, but there is nothing more rewarding than the beautiful blooms these exotic hibiscus produce.
Grafted v. Grown on their Own Roots
Hibiscus 'Creme de la Creme'
Must be Grafted
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In the early days of hybridizing exotic hibiscus, few cultivars, or varieties, could be grown on their own roots. So almost all exotic hibiscus were grafted onto a tougher garden variety type of rootstock. With the newest modern cultivars this is changing. Cultivars are being hybridized for their ability to grow their own sturdy root system, so grafting is often not required with today's exotic hibiscus. At HVH we grow many of our hibiscus on their own roots, but we do also graft some special varieties that can't be grown any other way. We choose the growing method that creates the strongest, most vigorous plant for each cultivar we grow.
Hibiscus 'Valentine's Day'
Grows on its Own Roots
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Does this help explain all these confusing terms? We hope this article gives you a reference to look them up again if you forget what something is and need to know!
Seedling of the Month...
'Winter Lights'
This month's seedling is one of our newest blue hibiscus varieties, 'Winter Lights.' Its beautiful pink and blue "light" effect comes from the mix of red and blue fire in its mother 'Nightfire.' But 'Winter Lights' has inherited a beautiful, lush, vigorous, upright bush that flowers prolifically from its father 'P's Purple.' 'Winter Lights' blooms with multiple 5-7" flowers that shine across the greenhouse like frosty twinkling lights. We hope to have 'Winter Lights' available for purchase in January 2010.
