Warm-Season Flowers for Your Garden

There’s no question that summer heat can be tough on flowers — it wilts delicate petals and stresses moisture-loving plants. But even when temperatures are at their peak, you can enjoy an explosion of colors in your garden.

Classic favorites like zinnias and sunflowers thrive when the mercury rises. So do exotic beauties like hibiscus and bougainvillea.

Here, we’ll explore blooms that thrive in hot climates, along with tips on planting and caring for them.

Understanding warm-season flowers

Generally, warm-season flowers have shorter germination periods than cool-season flowers. They grow quickly, and they’re more resistant to heat stress. 

What gives these flowers their heat-enduring superpowers? It depends on the flowers. Some have deeper root systems, which helps them access water in dry conditions. Others have waxy leaves, making them less susceptible to water loss, or their bright colors help them stand out to pollinators.

That said, it’s always important to select flowers that will do well in your region. You can refer to the USDA Hardiness Zone online for guidance or check with your local extension service or garden centers. 

Beautiful blooms to consider

Nasturtiums 

USDA Hardiness Zones: 9-11 (perennial), 2-8 (annual)

Planting tips: In warmer climates (zones 9-11), you can plant Nasturtiums in early spring or late summer. Nasturtiums prefer full sun, but they can tolerate partial shade, especially in hotter climates. Choose a spot with well-draining soil.

Care tips: Nasturtiums prefer to be kept on the dry side, so water them regularly but allow the soil to dry out between watering sessions. They are relatively drought-tolerant once established.

Anthuriums

USDA Hardiness Zones: 10-11

Planting tips: Anthuriums like a well-draining, peat-based soil mix. They thrive in indirect light, making them ideal for shaded garden areas.

Care Tips: Keep the soil consistently moist but not soggy. Anthuriums enjoy high humidity, so misting the leaves regularly can be beneficial. Fertilize every six to eight weeks with a high-phosphorus fertilizer to encourage blooming.

Dahlias

USDA Hardiness Zones: 8-11 (Select heat-tolerant varieties. Options include Bishop of Llandaff, Bloodstone, Juanita, Kidd’s Climax, Mystique, Orange Globe, and Thomas Edison.)

Planting tips: Plant dahlia tubers in rich, well-draining soil. Space them about 18-24 inches apart in a location with full sun. Use stakes to support taller varieties.

Care tips: Water regularly, especially during dry periods, but avoid overwatering. In extremely hot climates, consider providing some afternoon shade to protect the plants from the most intense heat.

Lavender

USDA Hardiness Zones: 5-9

Planting tips: Plant lavender in well-draining soil, preferably sandy or gritty, in a location with full sun. Space plants 18-24 inches apart for good air circulation.

Care tips: Lavender is drought-tolerant, so water sparingly once established. Prune back in the spring to maintain shape and encourage new growth. Avoid high humidity and overwatering to prevent root rot. (Some varieties, like French, French hybrid, and Spanish lavenders, can tolerate humidity, especially if the area has warm winters.)

Zinnias

USDA Hardiness Zones: 3-10 (grown as annuals)

Planting tips: Sow zinnia seeds directly in the garden after the last frost in well-draining soil and full sun. Space seeds or seedlings 6-12 inches apart, depending on the variety.

Care tips: Zinnias are low maintenance. Water at the base to prevent powdery mildew and deadhead regularly to promote more blooms. They thrive in warm weather and are drought tolerant.

Marigolds

USDA Hardiness Zones: 2-11 (grown as annuals)

Planting tips: Sow marigold seeds directly in the garden after the last frost or start indoors six to eight weeks before. Plant in well-draining soil with full sun exposure.

Care tips: Marigolds are very easy to care for. Water regularly but allow the soil to dry between watering. Deadhead spent flowers to encourage more blooms. In hot summer areas, some afternoon shade can help marigolds bloom longer.

Sunflowers

USDA Hardiness Zones: 2-11 (grown as annuals)

Planting tips: Sow sunflower seeds directly in the garden after the last frost. They prefer well-draining soil and full sun. Space seeds 6-12 inches apart.

Care tips: Water regularly, especially during dry spells. Taller varieties may need staking to prevent them from toppling over. Sunflowers are drought-tolerant once established.

Cosmos

USDA Hardiness Zones: 2-11 (grown as annuals)

Planting tips: Sow cosmos seeds directly in the garden after the last frost. They prefer well-draining soil and full sun. Space plants 12-18 inches apart.

Care tips: Cosmos are low-maintenance and drought-tolerant. Water sparingly and avoid over-fertilizing, as this can result in fewer flowers. Deadhead regularly to extend the blooming period.

Hibiscus

USDA Hardiness Zones: 9-11 (Hardy varieties like Rose of Sharon and Blue River II can grow in Zones 5-8.)

Planting tips: Plant hibiscus in well-draining soil with full sun to partial shade. Space plants 3-6 feet apart, depending on the variety.

Care tips: Water regularly, keeping the soil evenly moist but not waterlogged. Fertilize monthly during the growing season. Protect from strong winds.