Hi Carla, you can do either or…if you insert a plastic nursery pot, you would need to hollow out the head a bit more to accommodate the pot. But there’s more room for the plant if you just fill with potting soil. Remember, if you use the stone textured spray, it will wash off when exposed to weather. The styrofoam planter is better for a covered porch or patio or used indoors. I think these are so cool, I’m glad you like the idea, too! Let me know if you have further questions. Thanks for dropping by! ~ Kristen

Apologies for the delay. Concerning sealing styrofoam, I have wondered the same thing, myself. You could try a clear spray-paint top coat. The thing is, there will be tiny little pin-hole sized holes in the styrofoam that can trap water and dust/debris in the outdoors, which could promote mildew or moss eventually. You could also try researching on-line to see what ideas are out there that might work. I will try to do the same and if I discover something that works, I’ll update this post. Thanks for visiting Make it a Garden ~Kristen

Thanks for visiting Make it a Garden. I hope you have a lot of fun and creative endeavor with your project! – Kristen

Thank you Lorna—yes, like I said, there are LOTS of different spin-offs with styrofoam crafts. Many fun and whimsical ideas out there!