Sunflower (Helianthus annuus)
Tall, strong-stemmed plants produce huge, richly colored blooms. The flowers are packed with seeds that attract songbirds! One of the easiest and most satisfying flowers for your garden. Sunflowers are resilient and generally stay insect- and disease-free.
Ideal choice for beds, borders, and cutting gardens. Perfect for all kinds of containers. Cut flowers are long-lasting in fresh bouquets. Birds enjoy the seeds.
Keep soil evenly moist.
Organic-rich, well-drained soil.
Basic Care Summary
A heat tolerant selection. Plant in organic-rich, well-drained soil. Keep soil moist, watering freely in dry weather. Remove faded flowers or leave for winter interest.
Sunflower seeds are large enough to sow directly into the soil. You can sow the seeds when soil temperatures reach 45 degrees F although, ideally, the soil temperature should be about 60 degrees.
Lightly cultivate the sunflower bed on a regular basis, especially if a seed harvest is a goal. Weeds compete with the flowers for food. Heavy weed growth can reduce the number of seeds the sunflowers produce significantly. Use mulch between the rows, but do not allow the mulch to surround the sunflowers’ stems. This can keep too much moisture and lead to rot or fungal diseases.
Powdery mildew can be a problem during hot, humid weather, but the greater issue with sunflowers is drainage. Sunflowers are prone to verticillium wilt and this is particularly troublesome in heavy soils. Adding pelletized gypsum along with organic matter to clay soils can reduce some of the drainage issues. Planting the seed in raised beds or raised ridges can also help. To prevent verticillium wilt, avoid planting sunflowers in soil that grew potatoes, tomatoes, eggplant or peppers the previous year.
Prepare the garden by breaking up the existing soil (use a hoe, spade, or power tiller). Add organic matter such as manure, peat moss or garden compost until the soil is loose and easy to work. Organic ingredients improve drainage, add nutrients and encourage earthworms and other organisms that help keep soil healthy. Give plants an extra boost by adding a granulated starter fertilizer or a balanced all-purpose feed (for example fertilizers labeled 12-12-12).
Check the plant label for suggested spacing. Crowding plants can result in fewer blooms and weak growth as the plants compete for light. Exceptions to this might be regions with a short growing season, shade plantings which tend to grow slower and fill in less quickly, or a need to fill an area with color quickly such as for a special event or if planning to entertain guests outdoors.
Remove the plant from the container. If plants are in a pack, gently squeeze the outside of the individual plant cell while tipping container to the side. If plant doesn’t loosen, continue pressing on the outside of the container while gently grasping the base of the plant and tugging carefully so as not to crush or break the stem until the plant is released. If the plant is in a pot, brace the base of the plant, tip it sideways and tap the outside of the pot to loosen. Rotate the container and continue to tap, loosening the soil until the plant pulls smoothly from the pot.
Dig the hole up to two times larger than the root ball and deep enough that the plant will be at the same level in the ground as the soil level in the container. Grasping the plant at the top of the root ball, use your finger to lightly rake the roots apart. This is especially important if the roots are dense and have filled up the container. Set the plant in the hole.
Push the soil gently around the roots filling in empty space around the root ball. Firm the soil down around the plant by hand, tamping with the flat side of a small trowel, or even by pressing down on the soil by foot. The soil covering the planting hole should be even with the surrounding soil, or up to one inch higher than the top of the root ball. New plantings should be watered daily for a couple of weeks to get them well established.
Vining annuals require vertical space to grow, so provide a trellis, fence, wall or other structure that allows the plant to grow freely and spread.
New plantings should be watered daily for a couple of weeks. After that, depending on the weather and soil type, watering can be adjusted to every two or three days. Clay soils hold moisture longer than sandy soils, so expect to water more frequently in sandy settings.
Different plants have different water needs. Some plants prefer staying on the dry side, others like to be consistently moist. Refer to the plant label to check a plant’s specific requirements.
Ideally water should only be applied to the root zone – an area roughly 6-12” (15-30cm) from the base of the plant, not the entire plant. A soaker hose is a great investment for keeping plants healthy and reducing water lost through evaporation. Hand watering using a watering wand with a sprinkler head attached is also a good way to control watering. If the garden area is large, and a sprinkler is necessary, try to water in the morning so that plant foliage has time to dry through the day. Moist foliage encourages disease and mold that can weaken or damage plants.
To check for soil moisture use your finger or a small trowel to dig in and examine the soil. If the first 2-4” (5-10cm) of soil is dry, it is time to water.
Prune plants freely to maintain the desired size and shape. Pinching plants back stimulates dense, bushy new growth and encourages more flowers.
Remove old flowers to keep plant looking healthy and prevent seed production that drains the plant’s energy at the expense of forming new flowers.
Some plants are grown only for their attractive foliage (such as coleus, dusty miller and flowering kale). Their flowers are not very showy and any buds should be pinched off to keep the foliage looking its best.
Fertilizers are available in many forms: granulated, slow-release, liquid feeds, organic or synthetic. Determine which application method is best for the situation and select a product with a nutritional balance designed to encourage blooming (such as 5-10-5).
Too much fertilizer can actually damage plants so it’s important to follow the package directions to determine how much, and how often, to feed plants.
|Height Metric Range||1.2-3m|
|Space Metric Range||46-61cm|
|Available Colors||Orange, Yellow|
|Companion Plants||Sweet Pea, Hollyhocks, Canna|
|Lowest Temperature||40° to 50°F|
|Lowest Temperature Metric||4° to 10°C|
|Plant Light||Full Sun|
|Hardiness Zone||11, 12|