How do I get multiple Death Flowers?

I just wanted to point out that even without the Swift-Gro gardening station, you can distinguish a bit among special seeds, and therefore don't have to plant them all. All seeds found on the ground have the same value (seen if you try to sell from inventory) as a harvestable item with the same quality, i.e. a perfect apple seed will sell for ($)16. So an unknown special seed worth ($)75 will be an outstanding life fruit every time, with the caveat that the super green thumb LTR will push it to perfect once planted. It's therefore easy to avoid wasting your time caring for low-quality plants. Death flowers and money tree seeds are always worth ($)0, and in my games at least they don't glow on the ground or generate their own map tags with the collection helper LTR (although they're often found with life fruit or flame fruit seeds and their respective tags). And of course as soon as they sprout you can tell which is which.

If I'm feeling lazy I just use nraas MC to find the death flower seeds. Click on the ground (out in the world, not on a lot or the mod will only search that lot), select nraas>MC>object info>not inventory and a list of items will appear. Each type of special seed get its own listing, and if you select, for example, death flower seeds, you'll get a page for each dropping from the upper-right-hand corner. Click on each accompanying seed icon and the camera will center on the seed. There are usually around a half-dozen on the map at any given moment, although they do take a bit of time to respawn.