Could I grow these in pots & tubs?

I was asking on the main forum about gravel gardens, as I want one at the back of the house, (east facing). But on my travels I discovered some really lovely plants and was wondering if I could grow them in containers round the front, which faces south west and should get hot sun in summer. Some of these plants I have never heard of before so they might be rare or foreign.
The ones I loved are:
Agapanthus Back in Black
Agastache Black Adder
Eryngium Picos Blue
Festuca Elijah Blue - I'll get it for the gravel anyway but would it also grow in pots?

 

Agapanthus Back in Black is probably best in a pot where you are as it is a tuberous species and thus it is theoretically evergreen. If it turns arctic move the pot to the garage or similar.
I've never found Agastache to do as well in pots as they do in the ground. Deffo not hardy up there.

 

Drainage will be the key, fumanchu. All the plants you list need really good drainage, whether they're in the ground or in pots. Eryngiums are tap-rooted, so probably not ideal for relatively shallow pots. We need @silu !! She's got a wonderful garden full of terrific plants in Scotland, so she could advise you what is worth attempting. Silu....cooeee, where are you when we need you?

 

Drat. LOL! so much to learn... tyvm gardeners!