How to Grow Mexican Sunflowers (Tithonia)
Looking to attract butterflies and add bold, fiery blooms to your garden? Tithonia, also known as Mexican sunflower, is a drought-tolerant, heat-loving annual plant native to Mexico and Central America. It’s perfect for hot, dry areas—just the kind of plant I love! But there’s even more to love about Mexican sunflower. Its bright orange to red blooms are a real showstopper, lasting until the first frost and drawing in pollinators like bees, butterflies, and hummingbirds all season.
Article Outline:
- Meet Tithonia: The Heat-Loving Mexican Sunflower
- Plant Tithonia at the Right Time
- Choose the Perfect Location for Mexican Sunflowers
- Give Tithonia Plants Room to Grow
- Care for Mexican Sunflowers Properly as They Grow
- Enjoy the Blooms and Harvest the Benefits
- End of Season: Using Tithonia as a Cover Crop
Meet Tithonia: The Heat-Loving Mexican Sunflower
Tithonia isn’t just beautiful—it’s also practical. The plant’s deep taproots help improve soil structure and drainage, making it an excellent choice for gardeners in challenging climates. While it’s a perennial in tropical or subtropical areas like Mexico and Central America, in most regions, it’s grown as an annual due to its sensitivity to frost.
You can choose from several varieties, including the popular ‘Torch’ in yellow and orange or the dwarf ‘Fiesta del Sol,’ which grows only 2 to 3 feet (60 to 90 cm) tall and works well in containers.
5 Tips for Growing Mexican Sunflowers (Tithonia)
1. Plant Tithonia at the Right Time
Tithonia is a frost-tender annual that grows best from seed. Unlike its cousin, the sunflower, which easily germinates from seeds sown outdoors, tithonia seeds need light to germinate and can take 2 to 3 weeks to sprout. Start seeds indoors 6 to 8 weeks before the last frost date for the best results. Surface sow the seeds, cover them with vermiculite, and use a humidity dome to maintain moisture.
In warm climates, plant tithonia seeds directly in the garden once the soil warms to about 60°F (16°C). In the low desert of Arizona, start seeds indoors from December through March and transplant them outdoors from February through early May. Tithonia typically begins blooming around July, with blooms often lasting through early December.
2. Choose the Perfect Location for Mexican Sunflowers
Tithonia thrives in full sun, needing 6 to 8 hours of direct sunlight each day. It’s particularly well-suited to hot spots like Arizona, where it can handle even the intense summer sun. The plant prefers well-draining soil and can tolerate poor soil conditions, though avoiding heavy clay and overly rich soils is best. Compost is beneficial, but be careful not to over-fertilize, as you want the plant to focus on blooming, not just growing leaves.
3. Give Tithonia Plants Room to Grow
Mexican sunflowers are large plants, often growing 6 to 8 feet (1.8 to 2.4 meters) tall and up to 4 feet (1.2 meters) wide. These plants are great for adding height and privacy to your garden, and they look stunning at the back of a border, paired with other sun-loving plants like zinnias, marigolds, sunflowers, and basil. This combination is sure to attract plenty of pollinators!
Space tithonia plants 18 to 24 inches (45 to 60 cm) apart for optimal growth.
Pinching the center stem when the plant is about a foot tall will encourage a bushier, sturdier plant, potentially reducing the need for staking.
4. Care for Mexican Sunflowers Properly as They Grow
Tithonia is generally easy to grow and is resistant to most pests and diseases.
- Watering: Water regularly until the plants are established, then water deeply and let the top inch (2.5 cm) of soil dry out before watering again. Mulch around your plants to help retain moisture. Once established, tithonia is relatively drought-tolerant.
- Support: As the plants grow tall, especially in windy areas, it’s a good idea to provide support by staking them.
- Pests and Diseases: Tithonia is generally pest-resistant, but watch out for aphids and spider mites. Beneficial insects usually keep aphids in check, but if spider mites appear, remove affected leaves and spray the plants with water. See additional treatment methods in this blog post. To prevent powdery mildew, ensure proper spacing between plants and remove any infected leaves.
5. Enjoy the Blooms and Harvest the Benefits
Tithonia blooms are typically 2 to 3 inches (5 to 8 cm) wide, with colors ranging from yellow to orange and even nearly red, depending on the variety. These vibrant blooms, along with the nectar and seeds, attract a wide variety of wildlife, including butterflies, bees, and hummingbirds.
- Cut Flowers: While tithonia is not commonly used in arrangements due to its fragile stems, it makes a striking cut flower. Harvest the flowers in the morning when they’re fully open. Handle the hollow stems gently to avoid crushing them. If handled carefully, tithonia flowers can last about a week in a vase. Place the cut stems in deep, warm water for a few hours before arranging for the best results.
- Seed Saving: At the end of the season, allow a few of the largest blooms to remain on the plant and develop seeds. Once fully dry, snip them off and store the seeds in a paper sack. The seeds should be plump and well-formed, ready for planting next year.
End of Season: Using Tithonia as a Cover Crop
When the growing season ends, tithonia plants are an excellent choice for chop-and-drop mulch, helping to enrich the soil for the next growing season. You can leave the plants in place to attract birds to the seed heads or chop up the plant matter and leave it on the soil as a natural cover crop. Be sure to cut back the plants before the stems become woody or start producing seeds.
If you prefer not to use them as a cover crop, chop them up and add them to your compost; they’ll decompose quickly and help heat up the compost.
And that’s it! Your complete guide to growing beautiful Tithonia. If you have any questions or tips, feel free to leave a comment below. Happy gardening!
Good advice! I am wondering: Can tithonia be pruned into a smaller bush? I have some coming up from last year’s Big Mistake. I seeded what I thought were small zinnia seeds, but at 8′ + I realized those were definitely not zinnias! Now seedlings have come up and I know I need to either move them or trim back? Which should I do? I’m in Atlanta area and heat is already giving transplants problems.
They do tend to get large. You can keep it somewhat trimmed but it will get large. I wouldn’t attempt transplanting it at this point, just do the best you can.
There are varieties that only grow 3′ to 4″ tall.
Hello, I live in eastern Pennsylvania and have planted the mexican sunflower for the first time this year. All of the plants are blooming, except one.. The one that is not blooming has a stem about 4 -6″ around and is about 8-10′ tall. I’ve given it miracle grow and have pruned some of the branches back. It has tons of buds, but no blooms. How can I get it to bloom. Thanks in advance for your advice
hmmmm….. does it get enough sun? It sounds like it’s a good size. I would hold off on any more pruning to see if it will bloom.
Stop giving it Miracle Grow. The nitrogen is encouraging plant growth and not flowers.
Been growing Mexican sunflowers for years in my butterfly garden. They draw all sorts of butterflies and I love the nectar from this beautiful plant. I collect seeds and plant them every three or four months
Sounds lovely!
Does anyone know what type of soil they like? I am growing Tithonia Diversofloria. I would like to mulch with pine needles but they are acidic. Thank you in advance for any help!
They tolerate poor soil. Mulching with pine needles is fine.
Transplanted Oct. of 2021. It came up spring of 2022. Grew about 4 ft. wide and a little over 5 ft. tall. Full sun most of the day till about 4 or 5 in the afternoon. Never a single bloom. We had our first hard freeze this week. Sadly no flowers, any idea as to why.
That is strange, I’m not sure.
Could I plant in a large container? Do you think it would do well? I was given one, but don’t have the ground area to plant it until I make some changes and was thinking of using a large half ‘wine barrel’ planter full sun.
That sounds like a great idea!
I have a couple of Tithonia plants in full sun grown from seed from purchases seed pack that won’t flower at all. ( it’s now mid July in texas !). Have grown them in same spot before with great success. And I’m bummed with this big ugly giant with no flowers? Anything I can did to stimulate flower growth?
Might be too much nitrogen if there is an abundance of leaves. Try a fertilizer for blooms low in nitrogen if it’s not too hot.