The hardy flowering plant that survives scorching weather and fills backyards with clouds of butterflies

The lawn had already been scorched into something brittle and unyielding when the first butterfly arrived.

Another followed. Then several more. They weren’t interested in the veg patch or the roses, but in one wide, sprawling shrub lit up with violet flower spikes. While everything else sagged and suffered, this plant looked as though it belonged on a sun-baked Mediterranean hillside. Leaning over the fence and squinting into the glare, the neighbour asked the question half the street had repeated all week: “What on earth is that thing?”

Each time the wind threaded through the blooms, a light minty aroma lifted into the air. Bees moved along the stems like they were on a production line, butterflies paused and hovered as if time had slowed, and the garden seemed to thrum with a pulse of its own. No hosepipe, no shade cloth, no pampering-just a plant flowering confidently through the hottest week of the year.

One answer kept cropping up.

Agastache (hyssop / hummingbird mint): the drought-proof star butterflies can’t resist

The tough flowering plant everyone was pointing at is agastache, often known as hyssop or hummingbird mint-and it behaves as if heatwaves simply don’t apply to it. When lawns are under watering restrictions and pot plants crisp at the edges, agastache does the opposite: it basks in full sun and responds by producing even more flowers.

Its tall, candle-like flower spikes appear in rich tones of purple, pink, coral and soft apricot. The leaves carry a crushed-mint, aniseed scent that lingers on your fingers if you brush past. Butterflies, bees and hoverflies treat it like an all-you-can-eat buffet, looping from spike to spike as though nothing else in the border matters.

Once the roots have properly established, relentless heat feels less like a threat and more like something the plant takes on as a challenge.

In Phoenix-where summer can feel like stepping into an open oven-agastache has quietly earned a reputation as a go-to plant for back gardens. A local gardening group even ran an informal poll last year asking which plants were still blooming happily after three weeks above 38°C under strict water limits. Agastache landed in the top three, alongside lantana and desert marigold.

In one small front garden, a single clump of ‘Blue Fortune’ agastache became a minor neighbourhood attraction. A retiree tucked it into a narrow strip beside the drive expecting a modest burst of colour. By midsummer it had become a shoulder-high haze of blue-lilac spikes and flashing wings. Cars slowed, children pointed from windows, and someone even rang the bell simply to ask, “Can I take a cutting?”

That’s the understated strength of a genuinely heat-tough plant: it doesn’t merely endure harsh weather-it builds a small sanctuary for wildlife right in the middle of it.

From a botanical point of view, agastache is designed for extremes. Many types originate in bright, exposed parts of North America and Mexico, where rainfall is more hope than promise. Dense, fibrous roots spread deep and wide to hunt for any trace of moisture. Narrow, slightly coarse leaves reduce water loss, and the stems stay upright even as the ground dries out.

Because of that natural structure, it can sit through extended hot spells that would flatten thirstier perennials. Give it full sun and free-draining soil and it will often flower from early summer right through into autumn, sometimes even longer. A longer flowering season means more nectar for longer, which helps explain why butterflies don’t just visit-they seem to settle in.

In short: agastache doesn’t simply tolerate heat-it uses it as energy.

How to plant agastache so it thrives, not just survives

Establishment is the one stage where this plant benefits from your attention; after that, it becomes almost suspiciously easy to look after. The make-or-break period is the first few weeks after planting, when the roots decide whether to push downwards or sulk near the surface.

Pick the brightest, sunniest position you have-even the spot other plants have struggled to cope with. It needs well-draining ground: sandy or gritty is ideal, rather than heavy, sticky soil. Dig a hole only a little wider than the pot, tease the roots gently with your fingers, and set the plant so it sits level with the surrounding soil.

Then water properly-deeply rather than little and often-so the moisture travels down and the roots are encouraged to follow it.

In practical terms, a straightforward routine works best: during the first summer, water deeply once or twice a week, depending on just how fierce the heat is. Think long drinks, not quick sprinkles. After that first season, you can gradually reduce watering. In hot climates, established agastache usually manages on far less than most people expect, particularly if you add a light mulch around the base.

Don’t place it in low-lying areas that stay wet, or in pure clay that holds puddles after rain. This plant can cope with 43°C with no shade at all, but it cannot stand having “wet feet”. If your soil is heavy, work in coarse sand or fine gravel to improve drainage.

Once it has settled in, the most important task is often simply not over-managing it.

Let’s be honest: hardly anyone sticks to a perfect daily routine. The immaculate watering plans and pruning timetables in gardening books rarely survive real life, and agastache is unusually forgiving about that. Even so, two common first-time errors show up again and again.

The first is watering too much. In extreme heat it can droop slightly, which makes people worry and reach for the hose. Often it’s just temporarily flopping in the heat and will lift again by evening. The second is feeding too heavily. Fertilisers high in nitrogen can encourage lots of leafy growth at the cost of flowers-which is exactly the opposite of what you’re aiming for.

If possible, give it a light cut-back after the first big flush of flowers. A quick tidy with secateurs-or even kitchen scissors-often triggers a fresh wave of blooms and helps prevent it becoming lanky towards late summer.

“I planted agastache because I was tired of watching everything burn out by July,” says Maya, a self-taught gardener from Austin. “Now it’s the last thing standing in August, and the butterflies don’t leave it alone. I feel like I accidentally opened a tiny airport.”

That “airport” effect is what many people are really hoping for when they say they want a wildlife-friendly garden: not a single butterfly drifting through, but a steady, lively presence.

• For the best flowering, plant in full sun with free-draining soil.
• In the first summer, water deeply, then reduce watering thereafter.
• Steer clear of rich, waterlogged ground and avoid heavy feeding.
• Deadhead or lightly trim to prolong the flowering period.
• Combine different colours and heights to create a shifting, layered cloud of butterflies.

Why this one plant changes the feel of your back garden

On a still evening, once the heat finally eases, an established clump of agastache becomes more than just “a pretty plant”. The flower spikes catch the fading light, butterflies make their last unsteady flights, and bees drift back towards the hive with that slow, reluctant pace. You might find yourself standing there with the hose in your hand, realising you haven’t actually watered that plant for weeks.

Most of us have experienced the moment when the garden feels like another chore waiting on the list-somewhere that brings guilt rather than calm. Agastache shifts that balance. It demands less from you and returns more: not only colour, but movement, scent and sound.

One resilient, fragrant plant can quietly turn a dry, struggling garden into a space that feels lively again.

Key point	Detail	Benefit for the reader
Heat and drought tolerance	Agastache grows strongly in full sun and needs minimal water once established	Less time and money spent watering during heatwaves
Butterfly and pollinator magnet	Long-lasting flower spikes packed with nectar from summer into autumn	Your back garden fills with butterflies, bees and beneficial insects
Low-maintenance design impact	Tall, colourful spikes add height, fragrance and motion	A simple way to achieve a striking, “designed” look without specialist skills

FAQ: agastache (hyssop / hummingbird mint)

• Does agastache really cope with extreme heat? Yes. Many varieties are developed from species native to hot, dry regions, so once the roots are established they handle scorching summers well.
• How often should I water agastache? Water deeply through the first growing season-roughly once or twice a week in very hot weather-then reduce. In well-draining soil, mature plants usually need far less water than most perennials.
• Will agastache attract butterflies in a small garden or on a balcony? Yes. Even a single plant grown in a container can draw butterflies and bees, particularly when there aren’t many other flowers nearby.
• Does it return each year? Many varieties are perennial in suitable climates, especially where winters aren’t excessively wet and cold. Some behave more like short-lived perennials, but they often self-seed.
• Can agastache be grown in pots? Yes, provided the container drains well and isn’t allowed to become waterlogged. Use a gritty compost mix, place it in full sun, and don’t let the pot sit in a saucer of standing water.