Spring potted flowers question for rookie

[sundaypaper]

Rookie gardener here. I've got a small south facing front yard in front of my terraced cottage with a window box and pot plants on the gravel floor. It's quite a sun trap. In the summer I had geraniums and they were really the only successful plants I managed to keep alive. Lavender kept dying, as did other plants I tried.

I'm not much of a gardener and am time poor so I've got a pre-planted window box coming which should look like the attached image. I want to get a few more potted plants / flowers from B&Q garden centre to cluster around my door step which will look nice alongside the window box and which I can't kill!

A watering every few days and deadheadjng is do-able but I'd rather they didn't need replanting or anything too onerous etc.

Is there anything low maintenance and easy which will look lovely this Spring, aside from geraniums?

Thank you!

Have a look at the Sarah Raven website for gardening porn inspiration. Most things in a pot in a sunny spot are going to need quite a bit of water and a bit of feed every so often (tomato feed is good for encouraging flowers). Lavender are surprisingly fussy, they want good drainage and not too rich a soil, regular water but not to be soggy.

If you are going for the random riot of colour look (which I personally love) verbenas come in a billion colours, Bidens are a little yellow/orange job that is very sweet, and if you can get one of the shrubby salvias going they will be happy too (everyone has Hotlips because it is so easy to grow; rip off some bits from a friend and shove it in a pot and there’s a good chance it will be fine). Or Mediterranean herbs - rosemary, thyme, sage.

The bigger the pot the easier it will be.

Thank you! I should add, I want them to be in flower now and last at least the Spring. Does that apply to the above suggestions?