annuus (an-YEW-us) Annual
Sunflowers are supposed to be one of the easiest things to grow. If you feed birds you have probably found them coming up here and there all over your yard. How much can there be to know? I am a bit ashamed to admit that after growing sunflowers for the past 6 years for Good Scents, this was the first year I felt like I got the results I wanted. When it comes to growing sunflowers, as with so many aspects of gardening, the more I know, the more I realize I don't know.
I am only going to write about ornamental sunflowers, the ones grown for pretty flowers, not for seeds or oil. These started to become popular in the 90s with the appearance of pollenless F1 hybrids. Pollenless varieties are desireable for cut flowers because sunflowers produce copious amounts of pollen. When growing outside, bees collect and remove the pollen, but if cut and brought inside, the pollen instead collects on tables and counters creating a mess. Pollenless varieties produce little or no pollen and do not have this drawback.
Branching or Non-Branching?
Ornamental sunflowers can be either branching or non-branching. Branching varieties produce multiple stems growing out of the side of the main stalk, while the non-branching varieties grow a single stem and produce one flower at the top of it. If you are growing sunflowers to be enjoyed outside in the garden, the branching varieties are probably better. Branching sunflowers produce flowers over a longer season and have multiple flowers blooming at once at different heights on the same plant.
Each has its advantages, but for cut flowers I prefer the unbranched sunflowers. I experimented quite a bit with branched sunflowers, and while they produce many stems over a longer season, the stem length and the size quality of the flowers is variable. Because of their growth habit, branching varieties need to be planted quite far apart, at least 18 inches and up to 2 feet. This means they are not more space-efficient than the single stem varieties which can be planted quite close together unless you want the largest flowers possible.
In the case of sunflowers, bigger is not always better. A 6 or 8 inch diameter flower can be quite impressive outside but unless you are creating very large arrangements, a single flower that size can be hard to work into an arrangement. They are also so heavy that vases containing these huge sunflowers often tip over. Catalogs say to plant a foot apart for the largest flowers so this year I planted them about 6 inches apart and they were still about 4-5 inches across, plenty big for my purposes.
Most sunflowers are some flavor of yellow or another, from almost white to dark gold. On some the disks are brown and on others green. There are also some bi-colors with a ring around the disk like a giant black eyed susan, and quite a few that are described as "red" with names like Moulin Rouge and Claret. Red sunflowers are really a dark reddish brown mahogony color, like your grandmother's dining room table. For my taste they are too large and too brown to easily combine with other flowers for indoor arangements but they can look quite striking combined with other things outside. From what I can see all the red varieties are branching.
Varieties I Grow
The thing I didn't understand about sunflowers until this year is that to get a full season of sunflowers I needed to succession sow but also to grow varieties with different maturity dates with each sowing. In this way I got a continuous assortment of varieties coming into bloom all summer. I'd like to take credit for figuring this out myself but I read it in the Johnny's catalog.
These are the varieties I grew this past year with the number of days to maturity. All are single stemmed:
Premeir Lemon Yellow - pale yellow, black center - 40-50 days
ProCut Yellow - yellow, brown center - 50-60 days
ProCut Orange - dark yellow, brown center - 50-60 days
Orange Mahagony BiColor
Sunrich Orange - dark yellow, black center - 60-70 days
Sunrich Yellow - yellow, black center - 60-70 days
Sunbeam - yellow, green center - 70-80 days
How I Grow Them
Over the years I have tried starting sunflowers ahead in liners and direct sowing them. When started ahead and transplanted after a few weeks it seemed like the plants often ended up short and stunted. When I sowed them directly outside it seemed I never got them to sprout quickly or evenly. This year I compromised by starting them in liners and then transplanting them to the field as soon as the seed leaves had fully opened. This seems to be the best method for me. I get high germination quickly, and then by also getting the seedlings outside quickly, there is almost no transplant shock or stunting.