Hikari

Yes, sadly there is only a Despawn Self database script command for creatures and not for gameobjects, as you already mentioned.
Therefore one has to script the despawn of the plants in either SD2 or Eluna.

But in the long term it would be useful to introduce the Despawn Self command for gameobjects as well, because there are tons of situations and quests, where you need to despawn objects. I encountered already some of them.

Salja made a fix attempt a couple months ago for CoronaCore.

[url]https://www.getmangos.eu/server/9477-mangosone-2-4-3-quot-running-spot-issue-quot.html#post70411[/url]

Maybe it is a useful approach to narrow down the issue and finding a proper fix.