At least 2 inches sq. would be usable for getting something stuffed in. Is the concrete thick or just an inch; it may be that thicker concrete would require a bigger hole for getting started. I have only planted between flat stones, so never dealt with cracked concrete plantings. Okla. doesn't get as cold as your winters so not positive about what would be suitable all year. However, there are a lot of sedums and many are very tight to the ground and surely some of them would survive Utah. Creeping veronicas that are only about 1/2 inch tall are nice; one with 3 inch tall bloom spikes I use among my paver rocks. There are also other creeping veronicas with shorted flower spikes. Good luck. Sharon
Wooly achillea could be a possibility also. g

Sounds like a neat idea! I grow lots of sedums and they would probably grow ok in the cracks with a bit of gritty soil, but they are all succulent and fragile and I think they would tend to break off in a patio environment. I'd go with sturdy plants that could take an occasional trampling. There are many nice varieties of thyme and they smell nice when trampled. I think I would also consider dropping seeds and fine soil into the cracks rather than trying to stuff roots into a narrow space. You might also try Aubretia deltoides (Purple Rockcress) and Aurinia saxitilis (Basket of Gold) for perennials and Sweet Alyssum as an annual.

Moss rose would be sooo pretty!
Marsha

Any sedums that grow over cement and are trampled are literally turned to mush. It wouldn't kill the plant, save that portion, but I doubt it would be very appealing. Of course nothing will survive well trampling on a hard surface, but my bet is that anything succulent would be most unappealing. That said, the very tiny leaved sedums (eighth inch or less) would look very nice growing between the cement and not overflowing. Another good carefree one for the not overflowing would be hen & chicks (Sempervivum sp.). Otherwise, I think thyme could be your best bet overall.

I hope you have some good soil beneath the cement too. If plants will need to grow in the soil you fill cracks with only, sedums and semps may be the only thing that will grow there, unless you are willing to water your patio,LOL.

Still, I am a strong advocate of trying things if they have a chance, so I do encourage you to experiment. I found Alplains seeds do sell Veronica oltensis seed. A previous poster was looking for it and I hope she is reading this.

Rick

Hello to all. I have been lurking on the sidelines for more than a year and have finally decided it was time to register. I cannot beleive how many talented people are out there. My problem or question is My husband and I have built a good size pond with rock walls and a few flat slates (for plant pots). I want to plant in the rocks and cannot keep the soil in the cracks without washing out.How do you keep the soil in? Thanks