Strawberry is a seed plant. To produce berries out of strawberry flowers, we need to pollinate strawberries. There are mainly three ways to do pollination.
1. Insects like bees can carry pollen (outside in spring time)
2. Wind can shake strawberry flowers for pollination (outside or indoor by fan)
3. Touch pistils with cotton sticks or fingers (outside or indoor)
Since it is still before last frost date here in Oregon and I still keep strawberries indoor, today I used a cotton stick to pollinate strawberries. We need try to get pollen from stamens with the cotton stick and then touch pistil. In general, we need to cover the whole pistil area evenly to grow nice berries. Otherwise, berries could become strange shape. The worst case is it turns into brown color, which means that the flower failed to get pollinated.
If pollination is successful, the pistil remains green and it will become a green berry and graduatelly turn red and big. Then, time to taste our own organic strawberries 🙂