The One Flower Monarch Butterflies Depend on in Late Summer – Plant It Now for a Garden Full of Color and Wildlife

Bringing vibrant energy and color to the late summer yard, Mexican sunflowers (Tithonia rotundifolia) offer long lasting impact for very little effort or gardening know-how. Besides their rich orange blooms that last well into fall, these plants are simply irresistible to bees, hummingbirds and butterflies, introducing a fascinating extra dimension to your garden

Undemanding when it comes to growing conditions, these plants are plentiful across USDA Hardiness zones from 2a to 11b. Smothered with open, daisy-like flowers that have a rich concentration of nectar, tithonia blooms are particularly attractive to migratory butterflies and an important aid to the monarch butterfly migration.

Making their annual journey down both coasts of the USA to their breeding grounds in California and central Mexico, these remarkable butterflies rely on this particular plant for handy refuelling stops all along the route. To encourage this endangered species into your yard, you can find ‘torch’ Mexican sunflower seeds at Botanical Interests. Here experts share their growing tips.

How To Grow Mexican Sunflowers And Help Monarch Butterflies

Native to Mexico and Central America, tithonia is a heat loving and fast growing annual. Reaching up to 5-6ft (152-182cm) tall these flowers sit on top of long, slender stems making them perfect for cutting. An annual that thrives on neglect, these plants are largely disease resistant and perform well right up until the first hard freeze.

‘Tithonia is an easy-growing annual that prefers a spot with full, all-day sun and well-draining soil. It’s pretty drought tolerant and doesn’t appreciate a wet or soggy soil,’ says horticulturalist Justin Hancock. ‘Unlike a lot of annuals that benefit from regular fertilization, Tithonia can grow too fast, become brittle and leggy if it’s in soil that’s too rich.’

August is the time to direct sow tithonia seed. Soil temperature should be 70-85°F (21-29°C) for germination (a soil thermometer such as this from Walmart will help).

Sow seed around 1/4 inch (6mm) deep, cover lightly with soil, water and watch for germination which can take around 10 to 15 days. You can find heirloom Mexican sunflower seeds from Amazon.

The Best Spot For Mexican Sunflowers

Known as goldflower of the Incas, these specialist pollinator plants need a sunny, yet sheltered spot. 'Since these quick growers can have brittle stems, it’s best to give Mexican Sunflowers something of a protected spot from strong winds,' says Justin.

'Because it’s a large plant it’s best to position Tithonia in the back of the border, both so it doesn’t block the view of other smaller plants and because it’s relatively brittle, it may not be as obvious if flowers or branches break from strong wind, birds landing on it, etc,' he continues.

Amongst the best fall plants for privacy, why not grow this low maintenance plant in a movable planter, such as this metal planter box with trellis from Lowes, to surround a deck or patio.

Plants to Pair With Mexican Sunflowers

Thanks to it's late flowering period (from July until the first frost) Mexican sunflowers are perfect for pepping up already established annuals and perennials. With its bold orange, daisy shaped blooms and tall stature it works well alongside other long stemmed sun lovers with brightly colored blooms.

'Cosmos is an outstanding companion in my book,' says Justin. 'It has similarly shaped flowers, foliage that’s more delicate and textural, and likes the same hot, sunny conditions as Tithonia. Both are top picks for attracting butterflies, as well.'

Contrasting floral textures and opposing colors work brilliantly alongside these annuals, as Justin explains. 'Salvia (such as Black and Blue) is another butterfly and hummingbird magnet that loves the sun and doesn’t mind dry soil. While tall varieties of Verbena (such as Finesse, Lollipop, or Vanity) also share Tithonia’s preferred growing conditions, but give contrasting texture with their small rounded flower heads in lavender-purple.'

Find Salvia guaranitica 'Black and Blue' at Amazon and Verbena speciosa 'Imagination' seeds at True Leaf Market.

Justin Hancock

Justin is Costa Farms Horticulturist with 25+ years in the industry. A plant enthusiast and educator, he has a degree in horticultural science and has worked in garden centers and botanical gardens, as a garden designer, and in garden publishing. He has experience gardening across the country, from Minnesota to Oregon to Miami. Hancock is also co-host of the Costa Farms podcast Plant Rx.

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