If you are looking to collect your own sunflower seeds then you need to get organised. The seeds will be ready for harvesting once the flower head has fully dried. If you live in a warm and sunny climate then collecting the sunflower seed is a relatively simple affair as all you really need is a large brown paper bag. To begin with, the bag is placed over the flowerhead and secured at the base. It is there to both protect the drying seeds from being eaten by birds, and to collect the seeds as they begin to naturally drop from the flower head. It should only take a few days from the flowerhead to wilt until it fully dries and is ready for harvesting. Do not use a plastic bag as this will raise the humidity around the flowerhead and can encourage fungal rots to take hold and damage the seed.
1. The flowerhead will significantly droop on the stem
2. The old petals would have dried up and fallen off.
3. The back of the flowerhead would have turned yellow or brown.
4. The seeds will be hard and would have swollen to their recognisable shape as well as having their trademark black and white stripes.
If you live in a cooler, rain-prone northern European climate then drying out the flower head can take a little longer. This is a problem because sunflower seed heads are notoriously difficult to harvest if they are still moist. The same paperbag technique will apply but it will be done over a longer period of time. This means that it may need to be replaced periodically and if rain is due then you may need the added protection of a plastic bag. Just remember to remove the plastic bag at your earliest convenience.
Still keeping a brown bag over the seed head, hang it upside-down in a warm, dry and well ventilated position indoors. It will need to be hung a good height above the ground to prevent the seeds from being eaten by rodents.
Once ready, the easiest way to remove the seeds from the seedheads is to rub them together. Alternatively use a metal spoon to scoop them out of the seed head, you may find this to be a particularly satisfying experience. Once collected, rinse the seed in cold water using a colander as this will help to remove any dirt, bacteria or fungal spores that may spoil the seed at a later date. Allow the seed to dry fully on some paper towel before placing in a labelled envelope. Remove any diseased or damaged seed before packaging.