[header] How to grow tomatoes from seeds [title] Buy seeds or choose seeds from a tomato. [step] You can buy seeds online at seed exchange sites, from your local nursery, or from other gardeners. You can also buy seeds from the garden section of a department store. 
If you want to collect seeds from a plant, then you will need at least one tomato from that plant. Make sure the tomato is from a plant that was grown from an heirloom or open pollinated seed.