How To Grow Herbs Indoors

Who doesn’t love the taste of herbs cut fresh from the garden? Cold weather doesn’t have to spell the end of that enjoyment. In fact, you can grow bundles of savory herbs throughout all the seasons. All you need are some plants, a sunny window and a little TLC in the form of good soil, attentive watering and a regular supply of food. Continue reading

Flowering Kale: The Coolest Cool-Season Ornamental

Long before it became a trending food, flowering kale was a garden star, delivering a pop of color to fall’s graying landscape. The plant is not only prized for its striking foliage but it’s also one of only a few species that thrives in cold weather. Indeed, flowering kale likes cold temperatures so much that it often stays attractive well into winter. I can’t think of a better choice for fall gardens and containers. Continue reading

Great Small Trees For the Urban/Suburban Landscape

They say good things come in small packages. And when it comes to trees, I’d say that’s certainly true. While tall species like maples, oaks and elms boast lofty canopies, small trees flaunt their beauty up close. They’re a great addition to any landscape. But they’re especially suited to the smaller space, where even one, well-chosen specimen can brighten up a garden. Continue reading

Ten Minor Bulbs For Major Spring Impact

One of my favorite places to visit in the spring is the March Bank at Delaware’s Winterthur Museum. The estate’s stunning 60-acre naturalistic garden has one of the finest displays of minor bulbs around. Blooming in succession over a span of a few months, the bulbs weave a thick carpet of purples, pinks, blues, yellows and whites beneath the property’s centuries’ old trees. Faced with all that beauty, I vow each year to plant a few minor bulbs of my own. Continue reading

A Beginner’s Guide To 13 Types of Daffodils

In mid-summer, daffodils are rarely top-of-mind. But this is exactly the time when you need to be ordering them. And this is especially true for the more sought-after, unusual varieties. Why stick with yellow trumpets when daffodils come in so many other colors, shapes and sizes? See below if one or more of these different types of daffodils wouldn’t be the perfect fit for your spring garden. Continue reading

Pruning Hydrangeas: A Step-By-Step Guide For Old And New Wood

To prune or not to prune? This is one of the quintessential gardening questions. Recently, I asked a top landscaper in Virginia to weigh in on the issue. “When is the best time to prune hydrangeas without cutting off next year’s flowers?” I asked. 

“Never,” she replied with a laugh. “But your best shot is after they’ve bloomed.”

It turns out that knowing how and when to prune hydrangeas involves first, identifying what kind of shrubs you own. And it all starts with determining whether they flower on old or new wood. Continue reading

True Blue Flowers: 12 Of The Best And Brightest

For centuries, people have searched for a true blue flower. Elusive and rare, it is seldom found in nature. Or, to put it another way, it is rarely perceived in nature. It all has to do with what each of us sees as blue.

To find out why, I signed up for an on-line lecture given by Brandon George, a grad student working at Cornell Botanic Gardens. His research not only produced a great list of blue flowers, but also shed some (hint) light on the issue.

WHAT CONSTITUTES BLUE

So why is blue so rare in the plant world? For starters, I’ll ask you to refer to the color wheel below.

Blue is a primary color. On the visible color spectrum, it is located between green and violet. But that’s where things get murky. Take a look at the wheel. Some blues tend towards green, while others tend towards violet. Do all of these pigments merit the name blue?

This has turned out to be a problem for horticulturalists and growers worldwide. How are they to determine what is a true blue? At the moment, the Royal Horticultural Society (RHS) is the go-to authority. The RHS Colour Chart, created in 1966, contains 920 colors that can be matched precisely to flowers, fruits and other plants. It has become the primary means for communicating colors across the globe. 

Still, the color chart doesn’t explain why a true, pure blue remains so elusive. And here’s why. Though blue is a prominent color on earth, it is rarely produced in nature. In fact, of all the 280,000 known species of flowering plants, only 10 percent are blue.

HOW PLANTS PRODUCE BLUE

It turns out that plants aren’t born blue. Instead, like artists, they must mix naturally-occurring pigments to achieve their blue hue. The most common of these pigments are called anthocyanins. However, anthocyanins change their color depending on soil pH.

Hydrangea macrophylla ‘Nikko Blue’

In fact, just the tiniest tweak of metal ions in the soil can result in the same plant producing entirely different shades of blue. (Think blue hydrangeas, which are produced by adding acid to the soil.) Finding a true blue flower is really hard indeed.

WHEN PURPLE LOOKS BLUE

Even then, some of us may still see purple as blue.  Deutan Color Blindness (do-tan) is an anomaly of the ‘M’ cone (Medium Wavelength Light) in which spectral sensitivity is shifted toward longer wavelengths. If you have it, you may experience confusion between colors such as purple and blue. Take a look at the photo below. Do you see purple and blue or just blue?

Photo credit/enchroma.com

TRUE BLUE PRETENDERS

Nowadays, blue flowers are highly prized. As a result, growers are introducing more and more plants that are labelled as blue. But beware – many are not truly blue! To differentiate among cultivars, horticulturalists now use the term ‘true blue’ to indicate a more true blue pigment.

Take, for instance, the hardy geranium ‘Rozanne’, a popular choice for the perennial garden. Some growers list it as violet, others lists it as blue. How do you perceive it? To my eye, it tends towards purple. While my client sees it as blue.

Hardy geranium ‘Rozanne’/Photo: anniesannuals.com

And have you ever wondered why the same blue plant can look entirely different across catalogs? Just because a plant has blue in its name doesn’t necessarily mean it’s blue. Some growers manipulate photos to make plants appear more blue. Still others use tricks of light. If you can’t see the plant in person, George recommends consulting user uploads rather than seller photos to get a better perspective on a plant’s true color.

TRUE BLUE FLOWERS

There is one plant family that typically produces the truest blue flowers in nature. Boraginaceae, also known as the forget-me-not family, includes more than 27,000 species. The plants of this family are frequently hairy and include such garden ornamentals as Virginia bluebell (Mertensia virginica), Lungwort (Pulmonaria), Forget-Me-Not (Myosotis)and Siberian Bugloss (Brunnera macrophylla). Horticulturalists agree that these are indisputable blues.

Virginia bluebells

Other indisputable blue flowers include Grape hyacinth (Muscari), Siberian squill (Scilla siberica) and Blue Drumstick allium (Azure allium), in addition to pH-sensitive Hydrangea macrophyllaNikko Blue‘, which in acidic soil (a pH below 6) will turn blue. 

Blue Drumstick, Allium caeruleum

And don’t overlook the sky blue flowers of Siberian larkspur (Delphinium grandiflorum), and Hardy plumbago (Plumbago cerastostigma), which are all great additions to the spring/summer border.

TRUE BLUE ANNUALS

Perennials not your thing? There are some great almost-blue annuals. Evolvulus ‘Blue My Mind’ is a dwarf morning glory with fuzzy, silver-green foliage. It looks great in containers or windowboxes, where it will happily trail over the edge.

Other great true-blue annuals include Cape Plumbago (Plumbago auriculata), a very light blue, Love-In-A-Mist (Nigella), and Gentian sage (Salvia patens), a tender perennial that has the deepest blue flowers you’ll find.

Gentian sage, Salvia patens

DESIGNING WITH BLUE

When working with blue, remember it is considered a cool color, so it will recede into the landscape. Consider bringing it forward to enjoy it and plant cultivars in mass for a stronger effect.

But a word of caution. Placing a lot of different ‘blues’ together will often cause some to look bluer than others (see below). To prevent this from happening, separate them out and plant them instead next to contrasting colors (such as orange or yellow), which will give the illusion of a brighter blue.

Blue or purple? Delphiniums growing in Dalat, Vietnam