10 Gardening Tips From High Hampton's Dahlia Expert

Growing up in the Lowcountry, Drew English, High Hampton’s head gardener, was a hobbyist gardener well-versed in the plants that thrive in South Carolina's long and humid summers. But, as many hot weather residents do, English began to spend more time escaping to the cooler temperatures of the mountains.

He fell in love with the lush landscape of Cashiers, North Carolina, a resort town tucked away in the Blue Ridge Mountains, and, on one trip, a friend's great aunt delegated the younger contingent to go over to the dahlia garden and collect a few blooms for the dinner table. "I emerged through the rhododendron hedge and saw this sea of color," recalls English.

The dahlias would become a life's calling. When English moved to Cashiers full-time, he dove headfirst into learning all about dahlias and perfecting his gardening approach to the luscious blooms. Soon, he added award-winning dahlia grower to his resume, and the clients came calling. He launched his business, The English Gardener, and was asked to take over the heralded High Hampton dahlia garden.

Today, he tends to the hundreds of blooms in the High Hampton dahlia garden, and he's sharing his top gardening lessons for growing dahlias.

Buy Tubers From A Reputable Grower

Before you start your dahlia garden, make sure you're getting tubers from a reputable grower. There are diseases that can strike your tubers, and you may have no idea until they sprout that you've bought infected plants.

"Gall is tuber based, and it rapidly produces through cellular regeneration," explains English. This disease can cause misshapen shoots, but there's no way to spot it ahead of time—a trusted source is the best way to avoid gall.

Choose A Color Palette

English is always on the lookout for new dahlia varieties, particularly when he's on garden-scouting trips to the United Kingdom and beyond. But, regardless of which dahlias are currently en vogue, English sees dahlia fans gravitate towards pinks, blushes, oranges, corals, and peaches year-after-year.

"Café au lait is another perennial favorite. This year, I'm gravitating towards rich jewel tones—the colors you would usually associate with autumn, and I always say, add a little red," adds English.

Have A Plan For The Heat

English explains that dahlias love warm, mild weather, and they'll shut down when temperatures are above 90 degrees Fahrenheit. If you live in a climate where summer temperatures regularly soar towards 100 degrees, pot your dahlias. This way you can move them around on summer's hottest days and avoid the scorching sun.

Also, look for smaller, simpler blooms rather than intricate varieties or dinner plate dahlias.

Know That Dahlias Always Catch Up

The window to plant dahlias is wide, ranging from mid-April to June. Once the early summer temperatures set in, they grow quickly. "It doesn’t matter when you plant, they’ll catch up by mid late July," says English.

Start Spraying As Soon As You See Green

The new growth of dahlias is tempting for a host of garden pests. "As soon as you see green, start spraying, Put slug bait around the beds—they love the young tender shoots." says English.

If you don't take action early, thrips and aphids will get into the new growth, and you won’t see the damage for weeks. Japanese beetles are a threat as the plant continues to grow, leaving a holey trail in their wake.

Plus, there are several highly contagious mosaic viruses that are incredibly detrimental to dahlias. These diseases are transmitted through sap via bugs that jump from plant to plant or on a pair of scissors that's used to cut one plant, then another. That's why English has a strict rule when guests come into the garden to cut blooms—the shears must be sanitized between each cutting to avoid spreading disease.

Prune At The Right Times

Pruning at just the right times is key to keeping your dahlias blooming abundantly throughout their long season, which stretches from mid-July through the first frost. In English's words, "All they want to do is grow and bloom."

But you have to give them a little nudge to do so.

English recommends pruning just before the bloom season to disbud extra buds and foliage around a main center bud. "This allows the hormone that runs through the plant to focus on one singular bud and promote the best bloom possible."

He notes that if lateral blooms are allowed to flower, they'll often be a third of the size if and when they open, and the quality will never be as lush, layered, and vibrant as the center bloom.

Pruning should be repeated after the first big bloom to focus the plant's energy on producing the next round of blooms.

Use A Staking System

While English was in the United Kingdom in 2023, he discovered a new staking system that he's trying out in the High Hampton garden. He keeps the plants pruned to no higher than five feet tall, and there is criss-crossing grid of garden twine helping the plants stay upright.

Cut Then Sear The Stems For Long-Lasting Flowers

Of course, the best part of these vivid, layered blooms is using them in floral arrangements in your own home. English leads groups through the gardens throughout the flowering season to cut their own dahlia bouquets, and he has a few rules for long-lasting blooms.

First, sanitize the cutting shears or scissors between plants. Then, count down at least two or three sets of leaves—you want a long stem. If you lose a few buds along the way, that's okay. Once you've cut your stems, sear them in hot water for three to four seconds to help them last. Give them fresh water every day.

"The bigger, thicker blooms will last seven to ten days if properly cut," says English.

Continue To Deadhead Throughout The Season

Bloom season can be extended up until frost if you prune and deadhead throughout the season. Go in and clean up the tired blooms, cut back leggy height, and continue to make sure each stem is focusing all its efforts on just one bloom.

Lift Tubers After The First Frost

Part of the beauty of dahlias is that one tuber can turn to three or four the next year, but English is careful to give his tubers TLC as soon as the season wraps. He explains that you'll go from gorgeous fall blooms one day to a graveyard of dahlias the morning of that first frost. That's when the work is about to begin.

"Let the tubers rest two to three weeks after frost then lift them from the ground. Clean, sort, and tag them. Then keep the tubes in location that's below 50 degrees Fahrenheit, but above freezing," recommends English.

When the tubers emerge the next spring, you're ready to start the process all over again, but this time with an even more abundant garden.