I have a old dinghy that I have planted with herbs, but there is still plenty of space because the herb plant are still quite small. I chucked in (I’m not a gerdener) some nastertium seeds and they looked lovely growing round the herbs. They’ve finished now. What can I plant that will fill in the gaps and look pretty and interesting and survive my black fingers? Needs to be an annual because I reckon the herbs will have grown big enough by next year.