Although the annual sunflower (
annuus cultivars readily reseed in the garden if they haven't been deadheaded before self-sowing occurs. Instead, look at the flowers. Perennial varieties are native plants, and the blooms tend to be more modest, though they're still shaped like daisies, with petals that radiate from the center.
Helianthus occidentalis. This North American native perennial sunflower reaches 4 feet in height and produces orange-yellow blooms in late summer and early fall. Full sun is best for this species, but it tolerates poor or sandy soils and droughts.
Sunfinity Hybrid sunflower is the first annual sunflower to bloom continuously from late spring through the end of summer. Each branching plant produces an average of 50 golden yellow, 3-4 in. flowers and well-grown plants can produce over 100 blooms.
At the end of the season, it's easy to harvest sunflower seeds to dry for re-planting, baking up for a tasty snack, and re-purposing into suet cakes to feed the birds in the winter months. Sunflowers are ready to harvest when their foliage turns yellow, the petals die down and the seeds look plump.
Annual and perennial sunflowers should be cut back in early spring to promote branching, creating a full plant. Do not prune annual sunflowers after buds appear. Step 2 - Cut back perennial sunflowers a second time around mid-summer.
Sunflower seeds are easy to collect and store for planting next year. Just let the flowers go to seed, then harvest the seeds and keep them in a cool, dry place. Saving sunflower seeds is a great way to get free seeds for your garden, and it's also a fun project for kids.
Perennial sunflowers need a dormant period, so they do not make good winter houseplants. The growth dies in the fall, and the roots need time to rest and gear up for the next growing season. Leave landscape plants outdoors, move container-grown plants to a protected area, and wait until spring.
Also, since they produce so many flowers for such a long time, they are great in containers on patios, porches and decks where their smiling flowers can be seen all summer long. DO THEY NEED TO BE DEADHEADED? No, they do not require any additional care such as deadheading.
With a garden height up four feet and a spread of more than two feet, Sunfinity excels in the summer landscape all season long. Plant in a garden bed outside a window and be greeted with a sunny smile every morning.
It's important to note that while most sunflower varieties are annuals, many will reseed themselves if left to the end of the season on their own, especially if there are critters around the planting site to help spread the seed.
Plant perennial sunflower in an open area that receives at least 6 to 8 hours of sun a day. Water whenever the soil feels dry to the touch, but once established, perennial sunflower rarely needs supplemental irrigation. To promote continued bloom, clip flowers as they fade.
Remove sunflower root balls from the soil.
Once dislodged, sunflower root balls should be removed from the soil as much as possible, as it will be hard to plant around the tough roots. The woody root and stalk won't compost very quickly, so consider burning them instead.
Perennial sunflowers can usually be found in varying shades of gold, with a few cultivars in a softer lemon yellow. The foliage differs among many of the sunflower species. While sunflower leaves tend to be coarse in texture, there are some exceptions, such as Helianthus salicifolius, which has fine foliage.
Sunflower Sunfinity
Sunfinity comes into bloom in late spring and keeps on growing long after traditional single-stem sunflowers have bloomed and died. Sunfinity Sunflowers have lots of blooms that can be cut and used indoors. Continuous blooms all season long – over 100 blooms on one plant during the whole season.
A good general rule for pruning perennial sunflowers is to cut them down to half their size in the late spring or early summer. Then, reduce their size again by a third in June or July. Keep your warm climate in mind.
Keep them deadheaded until the end of the season. If you deadhead your sunflowers, they will keep pumping out new blossoms in their will to create seeds and more sunflowers. Don't cut the stalk way back, the next sunflower often forms just inches from the place you deadheaded.
Seed harvesting
Leave the flower head on the stem for at least 2 weeks.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
Sunflower is most susceptible to frost injury at the bud (R4) and flowering stages (R-5.0 to R-5.9) of development. Temperatures of 30 °F (-1 °C) or less can cause damage to the anthers and stigmas of the pollinating disk flowers.
You can keep your sunflower in a warm, bright, dry location indoors throughout winter. Sunflowers can survive winters, but their flowering will likely be duller in color.
Crazy enough, if sunflowers are grown year after year in the same spot, even their own seedlings will eventually start to suffer themselves from these toxins that the adult flowers naturally release into the garden soil.
So how late can you plant sunflower seeds? With varieties that only require a 50-60 day growing season, you should be able to plant sunflowers as late as July for fall flowers. If you live in a warm climate where the first frost comes well into late fall, you can plant sunflowers even later in the season.
For example, sunflowers should not be planted in the same field more than once every three to four years because of high susceptibility to sclerotinia head rot; the same applies to soybeans because of cyst nematodes. Regular crop rotation also reduces the likelihood of weeds building tolerance to herbicides.