100 Mixed Succulent Plant Seeds You can start seeds in almost any type of container, as long as it’s at least 2-3 ” deep and has some drainage holes. If you love to DIY by yourself, you might start growing seedlings in yogurt cups, milk cartons or even a paper cup. Choose the potting soil that’s made for growing seedlings.(NOTE: Do not use soil from your garden or re-use potting soil from your houseplants. Start with a fresh, sterile mix that will ensure healthy, disease-free seedlings.) Some of the small ones can be sprinkled right on the soil surface. Larger seeds will need to be buried. After planting seeds, you have to moisten the newly planted seeds. To speed up germination, cover the pots with wet paper or a plastic dome. This helps keep the seeds moist before they germinate. When you see the first signs of green, you have to remove the cover.