I only sow with easy hardy annuals but I rarely get good results. When I sow in open ground they usually don't appear at all ?eaten by slugs/snails.
I have sown nasturtiams, calendula and trailing sweet pea in pots, a basket and a window box all in the same (smallish) back garden. As usual a lot of disappointment despite dead heading and having put in a slow release fertiliser tablet at the beginning of the season. I have an automatic watering system so I suppose the fertiliser is washed away after some time, but then don't annuals just make leaf and no flower if overfertilised?
Fortunately my field poppies do well, but the dead heading is a bit laborious.
I pass gardens with hardies much earlier than I get them and full of bloom too.
Those in the widow box do better than in the smaller pots. I've bought lobelia before and it has been ok , but not like the abundant waterfall that I see
Where am I going wrong?