Curious about when to plant sunflower seeds? These cheerful flowers can fill your garden with vibrant colors from July to October.
There are three primary types of sunflowers: annual helianthus, perennial helianthus, and tithonia. Once you understand how to cultivate them, timing is key to enjoying their height and beauty. Plus, many of these varieties make excellent cut flowers and attract wildlife.
Our helpful guide will provide all the necessary details on when to plant sunflowers of each type, along with expert tips to ensure they flourish in your garden.
Timing for Planting Sunflower Seeds
When to plant sunflower seeds varies by type. Annual helianthus and tithonia can be sown indoors in March or April or directly into the ground in late spring or early summer. Perennial helianthus should be planted in spring or fall.
Annual helianthus, especially the giant yellow ones, are great for kids. The large seeds are easy for even toddlers to plant. Consider hosting a family contest to see who can grow the tallest sunflower!
Stylish dusky pink and claret-colored annual helianthus, along with bold orange tithonia, can enhance your flower bed designs and brighten up vegetable patches. Yellow perennial types, like 'Lemon Queen,' work wonderfully as border plants.
Annual Sunflower Seeds: Planting Tips
Growing annual sunflowers, such as the impressive 'Russian Giant' or the elegant terracotta 'Earthwalker'? These should ideally be sown indoors in early spring; otherwise, direct sowing later in the season is also effective.
Starting Indoors
As a half-hardy annual, helianthus annuus can be started indoors in a greenhouse, cold frame, or sunny windowsill during March or April for earlier blooms. Use seed trays for sowing and transplant seedlings into individual pots as they grow. Once they reach 12 inches (30 cm) tall, they can be planted outside.
Direct Sowing
For direct sowing, annual sunflowers should be planted in well-drained soil outdoors between mid-April and mid-June. They thrive best when sown 2-3 weeks after the last frost or once the soil warms up. According to horticulturist Shannie McCabe, sunflowers dislike cold conditions.
Perennial Sunflower Seed Planting
Opting for perennial sunflowers? Varieties like golden 'Capenoch Star' and 'Lemon Queen' can be planted in the ground during spring or fall.
In spring, place perennial sunflowers in the back of sunny borders with neutral to alkaline soil. Enhance water retention by mixing in organic matter like well-rotted manure. Protect from slugs.
In fall, trim back spent flower stems and incorporate organic matter into the soil before planting perennial helianthus at the back of a sunny border.
Mexican Sunflower Seeds: Planting Details
The Mexican sunflower (Tithonia rotundifolia) boasts stunning bright orange flowers on tall stems from mid-summer to late autumn. This variety attracts butterflies and is excellent for cutting. 'Torch' is a standout choice. Sow it indoors or directly in the soil.
Starting Indoors
As a half-hardy annual, tithonia is best sown indoors in early or mid-spring for earlier blooms. Nina Marshall from Chiltern Seeds suggests starting seeds in March or April in a warm environment between 55 to 65°F (13 to 18°C).
Be patient after sowing, as tithonia can have a slow start. Catherine Kaczor from Hudson Valley Seed Co advises not to worry if it seems to lag; it will eventually thrive.
Direct Sowing
Once the weather warms in late spring, you can sow Mexican sunflowers directly into the soil. Nina Marshall notes they begin to flower abundantly when sown in the first week of May.
Choose a sunny spot with well-drained soil, ensuring there's enough space for tithonia to grow, as it can reach heights of 6 feet (1.8 m) or more. Avoid excessive fertilization, which can reduce blooms and increase foliage. Tithonia is low-maintenance and delightful to grow, attracting many pollinators when in bloom.
Planting Sunflowers in Pots
Compact annual helianthus can thrive in pots filled with well-drained compost on sunny patios or windowsills, making them a fun project for children. Consider varieties like 'Short Stuff' or the fluffy 'Teddy Bear,' which remain relatively small.
Shannie McCabe recommends 'Teddy Bear' for kids; they grow to only 18 to 24 inches tall and have fully double petals, making them look fluffy and inviting. These plants mature quickly and are easy to care for.
For pot planting, you can start annual sunflowers early indoors in March or April in their final containers. Alternatively, sow them outdoors from mid-April to mid-June in the pots they will grow in. Select a well-drained pot that can accommodate the dwarf sunflower's full size, typically around 2 feet (60 cm). Position pots in direct sunlight, water regularly, especially during hot spells, and anticipate cheerful blooms come summer.
