By Lois Hoffman
Hydrangeas have the power to change color depending on what type of soil they are grown in.
They are vibrant, showy and naturally claim the spotlight. No wonder, in my mind, they are the “happy plant.”
Hydrangeas are probably the plants that you remember in your grandmother’s yard or garden. Because they steal the attention, they are often planted at corners of homes or at the focal point in gardens. It is easy to landscape around them with other perennials and annuals. Besides being showy, what captivates folks about them is the fact that they have the ability to change colors, with the most notable ones being pink and blue.
I never gave these much thought until we were driving some backroads last year and I noticed this large, vibrant plant with cone-shaped blooms that started out cream colored and slowly transitioned to pink. When we stopped to inquire, we were introduced to the vanilla strawberry hydrangea. I was hooked and had to have one.
Since then, I have become hooked on all hydrangeas. At first it was the large vibrant blooms that caught my eye but, since then, the fact that they are hardy plants that bloom year after year and add so much color and charm to gardens have moved them up among my favorite garden plants.
Also known as hortensia, hydrangeas are most common as shrubs but can also be trees and climbing vines. Some are so small that they can be planted in perennial borders and some vines grow as high as 100 feet.
Besides their big, showy flowers, people are falling in love with them all over again because of their variety of shapes, sizes and colors. Most species bloom from early spring to frost and come in shades of pink, blue, white, purple and green.
The word “hydrangea” comes from the Greek word hyder, meaning water and angos, meaning vessel. Roughly translated, this means water barrel which is aptly named for the up-shaped flowers which require lots of water. Here in the United States, hydrangeas are given for fourth anniversaries to symbolize appreciation and heartfelt emotion.
These showy flowers love sun to part sun. Since they get so thirsty, the best time to plant is in the spring or fall. The hot, dry summers are stressful on them to get started since they do require lots of water. Northern climates pose a little more diligence to bed them down for the winter so they don’t winter kill.
Some folks have tried to make them houseplants, usually unsuccessfully for many reasons. First and foremost, each variety needs their own amount of sunlight. Moisture and humidity are big failure factors also. Indoor air tends to dry out faster and hydrangeas like enough humidity without having wet feet. Even if you get these factors right, some varieties require cold periods of two to three months where they can hibernate.
Sadly, many “gift” hydrangeas from the stores are not bred to last more than one season. Their big attractive flowers are the draw but, even though they are classified as perennials, they are more like annuals.
Of course, the big thing about hydrangeas is their ability to change color, depending on the nutrients, or lack of, that they receive. Primarily, their colors are either blue or pink. Unlike other plants, their colors can change dramatically, all by adjusting the pH of the soil. Some change color on their own when they are planted or transplanted by simply adjusting to their new environment. For this reason, during the first year, a plant can actually have more than one color of bloom at the same time.
This color change has to do with the amount of aluminum in the soil. Either subtracting or adding this to the soil, determines if the blooms will be pink or blue. For this reason, it’s much easier to alter the pH of the soil if the hydrangeas are planted in pots.
Forcing pink blooms can be accomplished in different ways. Dolomitic lime can be added to the soil several times a year to raise the pH level. Aim for a pH of 6.0 to 6.2, if it goes higher you risk an iron deficiency. They take up aluminum best at lower pH levels, raising it will help to keep the blue color.
Be sure and fertilize with high levels of phosphorous since it helps protect from the aluminum creeping in. Use a ratio of 25/10/10 (phosphorous is the middle number). If aluminum occurs naturally in the soil, your best alternative is to grow hydrangeas in pots, using a soilless mixture which probably doesn’t have aluminum in it.
On the other hand, if you want to change the color from pink to blue, add aluminum sulfate during the growing season at a ratio of one tablespoon per one gallon of water to plants that are two to three years old. Water well in advance as adding too much can burn the roots. Another method is to add organic matter like coffee grounds, fruit and vegetable peels or grass clippings. For the aluminum to be available to the plants, the pH should be low, ideally around 5.2 to 5.5.
When fertilizing, choose one that is low in phosphorous and high in potassium, a 25/5/30 (potassium is the last number) mixture is good. If you have high alkaline soil naturally, again it is best to grow them in pots. Another thing to watch for, test your water to make sure that it is not contaminating your soil with unwanted minerals. Also, avoid planting by sidewalks or concrete as lime can leach out.
Although hydrangeas are primarily found in colors of pink and blue, others are sometimes seen. White hydrangeas are white, they cannot be altered. There is no such thing as true red even though hot climates produce some almost-reds. Purple hydrangeas are some of the most eye-catching and are hard to come by. The soil conditions must be exactly right, the pH is directly centered so purple is right between pink and blue. Heredity and health of the plants and weather conditions all affect the intensity of colors.
Now, what peeked my interest in hydrangeas in the first place, the vanilla strawberry variety. Even the name itself is enough to draw you to it. It was developed by Jean Renault in France and is one variety of Panicle hydrangeas. Others in the group are Strawberry Sundae and Fire Light. Vanilla strawberry was voted top plant of the year by the American Nursery and Landscape Association in 2010.
It is characterized by emerging creamy white cone-shaped blooms in mid-summer that slowly transition to pink and then strawberry pink in the fall. It is hardy, low maintenance and sun loving. As a bush, it grows nearly seven feet high and five feet wide. What’s not to love?
Besides their showy blooms, the leaves of hydrangeas produce large shady areas underneath. These are perfect spots to plant shade-loving plants like hostas. Their colorful leaves add interest and more color to the area. You can also fill in with annuals to round out a planting area.
It boggles my mind that I have never discovered hydrangeas before. I love the idea of a plant that offers lots of color with low maintenance. No wonder I think of them as happy hydrangeas!
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