This year I decided to try growing sunflowers as part of my vegetable garden so that I could harvest the seeds. I bought a packet of what were described as medium-sized sunflowers and planted seeds along with my other vegetables at Labour Weekend (end of October for anyone outside New Zealand). The birds went berserk in my garden this year, digging up all my seeds and many of my seedlings while looking for worms. I had to replant 3 times and eventually got 2 sunflower plants to grow from my entire packet of seeds.
These 2 sunflowers grew really well and got taller and taller. One reached about 2.5m tall with a massive ‘trunk’ about 5cm thick. Just as well I didn’t choose the tall sunflowers!
It was a delight to watch the bumblebees and monarch butterflies visiting the flowers regularly. One flower was about 30cm across.
Sunflowers are ready to harvest once the petals die back and the backs of the flowers turn a yellowy brown. It is also a tell-tale sign if the birds have started to do their own harvesting of the seeds. When I harvested the largest flower I was really surprised by how heavy it was – it weighed 1.5kg! You are supposed to cut the flowers with about 30cm of stem so that you can hang the flowers upside down to complete the drying process. It is a good idea to cover them with a paper bag to catch any seeds that might drop. After a week or so, I rubbed off the fuzzy covering leaving just the black seeds. Then I left it for another couple of weeks until the seeds were drying out and easy(-ish) to remove.
Excited about my harvest and already planning what I was going to do with the seed bounty, I removed all the seeds onto a paper towel. I was a little surprised at how light the seeds were – the whole lot weighed just 75g. Imagine my disappointment as I started to remove the black outer shell to expose the inner seed and discovered that virtually none of of them had a seed inside. All of that effort for no reward! I still don’t know what happened: the soil was nice and rich; there was a constant stream of pollinators to the flowers; and modern sunflower hybrids are often self-fertile anyway. Unfortunately I stupidly didn’t keep the packet the seeds came in so I don’t know what variety they were.
Does anyone have any suggestions for what might have gone wrong?