If you can take the soil out and put a liner in the bottom to keep it from draining too much, I would suggest just that. Then plant both! Nasties and moss rose are lovely, I imagine that they'd be lovelier together!

FYI, those racks that were brought to the swap ended up being left behind. I debated if we should just ship them to my mom who lives in FL and can do the coco mats and she has FERNS growing in hers. Meanwhile in CO, we usually can't keep cactus alive in the dang things. Well, hubby decided that he really wanted to try to plant something in them, so we bought coco mats for them, put plastic bags inside the coco mats, and then put in some moisture-retaining soil (it's the ONLY time I'll ever buy Miracle Gro, but it's just for ornamental flowers, right?) and wayyyyy too many plants. Anyway, we water them not even every day, and things are blooming beautifully, with no wilt! I say, go for it!

Just an FYI. If your soil is too rich, the nasturtiums will grow plenty of big fat leaves but few or no flowers. Ask me how I know! :-)

Thanks to both of you. I've tried to find some "Nasties" - I like that nickname! - but all I can find at this point is seeds, so I'll just have to go with the Portulaca. I've had no luck growing from seed. For some reason containers of Nasties are hard to find here.

I have mixed compost into the barrel's soil, so it may be too rich for the Portulacas as well. Mayberry, I like your approach, but the barrel is huge, easily big enough for a 5-gallon purchased container, so there is no way that I am pulling all that soil out!

Did the same last year with Morning Glories, Kvenkat. Had a wonderful green wall of huge leaves, no blooms all year. Now I've got some Nasties going in several locations - and one's leaves are much bigger than others. All were direct sown, no blooms set yet. Worrying.