I found collecting Diplotaxis seeds tricky, they have tiny seeds and really short window of time when pods are dry (ready to harvest) but not open. And just a small shake of the plant can be enough for pods to split and tiny seeds go all over the place. Good for self-seeding, not so much for collecting seeds. So far I’ve managed to gather small quantities for sowing it in other places around the house. Right now I have some plants with maturing pods, crossing fingers I’ll be more succesfull this round
I haven’t tried black mustard so no idea on comparison…
It does make sense to try and get more seeds like that, but it just doesn’t fit to what I’m doing… Meaning it’s not a priority species for me, being a native plant and doing fine by itself (I’m just occasionally helping it move around the place), and my available ‘seed space’ is already overcrowded through the year, with a combination of drying seeds, sorting my stash or going through it for seeding purposes or exchanges, or sorting newly aquired seeds.
I also don’t mind it re-seeding some, and what I do collect I usually just direct seed at the wanted location at the same time.
I do have a mind to try and gather more seeds without having to cut it and bring indoors, and whatever I do gather will be used for setting up completely new gardening plot later this year
