Pistachio Hydrangea

Hydrangea macrophylla 'Horwack' (PP#25,577)

12 Reviews

Pistachio Hydrangea

Hydrangea macrophylla 'Horwack' (PP#25,577)

12 Reviews

This product is currently out of stock and unavailable.


How are the heights measured?

All tree, and nothin' but the tree! We measure from the top of the soil to the top of the tree; the height of the container or the root system is never included in our measurements.

What is a gallon container?

Nursery containers come in a variety of different sizes, and old-school nursery slang has stuck. While the industry-standard terminology is to call the sizes "Gallon Containers", that doesn't exactly translate to the traditional liquid "gallon" size we think of. You'll find we carry young 1-gallons, up to more mature 7-gallons ranging anywhere from 6 inches to 6ft.

How does the delivery process work?

All of our orders ship via FedEx Ground! Once your order is placed online, our magic elves get right to work picking, staging, boxing and shipping your trees. Orders typically ship out within 2 business days. You will receive email notifications along the way on the progress of your order, as well as tracking information to track your plants all the way to their new home!

Why are some states excluded from shipping?

The short & sweet answer is: "United States Department of Agriculture Restrictions." Every state has their own unique USDA restrictions on which plants they allow to come into their state. While we wish we could serve everyone, it's for the safety of native species and helps prevent the spread of invasive disease & pests. We've gotta protect good ole' Mother Nature, after all.

About Me


The Pistachio Hydrangea is a new, novel, mophead hydrangea with unique flowers. The dome-shaped heads of flower begin as a pale-green color. As they develop they turn exciting shades of chartreuse and pistachio green. Then tones of scarlet or violet develop, and the center turns clear blue, making a kaleidoscope of color that has never been seen before in hydrangea flowers. As well, these plants flower on both old and new shoots, so in warmer areas you have continuous flowering from summer to late fall, and in colder areas from late summer through fall. Wherever you live you can enjoy the beauty of this plant. It forms a broad shrub, 2 to 3 feet tall, and up to 5 feet wide. This is low and relatively small for a hydrangea, so it is an ideal choice for a smaller garden. This plant grows well in partial sun, particularly in situations with morning sun and shade from noon onwards. It also grows well in the shade on the north side of your home, and in light shade beneath deciduous trees.

  • Unique flowers in chartreuse green, scarlet, purple and blue
  • Perfect plant for partial or full shade
  • Blooms summer to fall in warm areas
  • Flowers from late summer through fall in colder areas
  • Easily grown in ordinary soil, but not drought-resistant

Grow your Pistachio Hydrangea in any well-drained garden soil. Its colors are stable in both acid and alkaline conditions, simply becoming a little more purple-red in very acid soil. It does best with plenty of water, so water new plantings twice a week, and water established plants at least weekly during any dry weather. Remember that beneath trees it may be dry, even after rain, so check the soil around your plants. Prune in spring to remove any dead stems, and even if all the branches have died, this hydrangea will re-sprout from the base and flower by late summer. This plant is easy to grow and does no suffer from pests or diseases.

Plant Hardiness Zones 5-9
Mature Width 3-5
Mature Height 2-3
Sun Needs Partial Sun, Shade
Zones 5-9

The Pistachio Hydrangea is a new, fascinating color form of Mophead Hydrangea, a popular shade-loving plant. Hydrangeas are widely grown in all but the coldest areas, for their dramatic flowers, and for blooming later in the year, when most other shrubs have finished flowering. They also grow in shady parts of the garden where most other plants will not thrive, so they are excellent ways to bring color and interest to those areas. Easily grown, these are essential plants for creating the main structure of your garden, and they should be part of the first plants you put into a new garden, or in one you are improving.

In recent years there has been an upsurge in breeding of these plants, and many new varieties have been created for gardeners to enjoy. Perhaps the most exciting is the Pistachio Hydrangea, which has unique flower colors that are stylish and contemporary, bringing something new to your color arrangements. The flowers of the Pistachio Hydrangea are carried in clusters of 40 to 50, in rounded heads that can be as much as 5 inches across. The individual flowers are one inch across, with 4 broad petals. Mixed among these flowers are secondary ones, which are tiny and fluffy, giving the flower head a novel, more airy appearance.

It is the colors, however, that really make this plant unique. When they first develop at the ends of the stems, they are pale green, but as the flowers mature they become toned with chartreuse or pistachio green, and then become flushed with scarlet-red to violet-red. To finish off this vibrant display, the center eye of the flower is bright, light blue. Each flower head is an ever-changing color palette, so that every day your plant will look different, and always fascinating.

Growing Pistachio Hydrangeas

The Pistachio Hydrangea is a fast-growing shrub, quickly reaching 2 or 3 feet in height with a broad spread of 3 to 5 feet. It is covered from top to bottom with attractive mid-green leaves about 6 inches long, with a toothed edge. This plant grows well in any well-drained soil, but it does need a steady supply of water to thrive, so young plants should be well-watered twice a week, and mature plants at least weekly during the summer and any in dry spells. Enrich the soil with organic material before planting, as this will improve both drainage and water retention. Mulch in spring with more organic material, to retain moisture, keep the roots cool, and provide nutrients to keep your plant growing vigorously.


The fascinating and unique flowers of the Pistachio Hydrangea are only the beginning of its special qualities. Most older varieties of hydrangea flower on shoots produced in spring from stems that grew in the previous year. In areas colder than zones 6 or 7, winter often kills these stems, so that little or no growth is held over from the previous season. This means that no flowers are formed. Also, with plants that only flower in this way, once the first flowering in summer in over, no more flowers appear on your plants.

The Pistachio Hydrangea, in contrast, flowers both on stems from older wood, but also on new stems that grow from the base. If you live in a warmer area, this means you have blooms in summer, and then more blooms in late summer and fall from the new growth. If you live in a colder area, you will have a spectacular flowering display in late summer and fall, of flowers formed on the new growth from the base. This is a ‘win-win’ for everyone – and a great reason why everyone should have this wonderful plant in their garden.

History and Origins of the Pistachio Hydrangea

The Mophead Hydrangea (hydrangea macrophylla) was introduced into Europe from China and Japan in 1785. It was probably brought over by both early settlers, and independently introduced into America by traders from the East in the second-half of the 19th century. It thrived in the south-east, with the warmth and good rain-fall. Over the years breeders around the world have worked to develop repeat flowering, to extend growing into colder areas, and to develop new color forms, to bring excitement and interest to our gardens.

Frau Katrin Meinl is a specialist breeder of hydrangeas, working in Dresden, Germany. It is to her breeding work that we owe thanks for the Pistachio Hydrangea. Working with established varieties, and her own seedlings, she made many crosses between different hydrangeas, and grew hundreds of seedlings to find this special variety, which is officially called ‘Horwack’. She found the plant in April 2006. After extensive trials she was granted a patent on her invention in 2015. Besides it unique coloring, repeat flowering, and compact size, this plant is also resistant to common hydrangea diseases, such as powdery mildew and botrytis.

Buying Pistachio Hydrangeas at The Tree Center

Our plants are produced under license, so you know they are exactly the Pistachio Hydrangea and not something else. You may find cheaper hydrangea plants, but they will not be this unique variety, that everyone is eager to grow in their garden. Don’t be left behind, and order now while our limited stocks last. Make sure you also view some of our other unique hydrangea varieties like the Nikko Blue Hydrangea and the Glowing Embers Hydrangea.

Back to top

Pistachio Hydrangea

Hydrangea macrophylla 'Horwack' (PP#25,577)

12 Reviews