Now that you mention it I do remember noticing that. Not sure why that feature is in place it would be cool if @LemonadeJoe could help me figure out a work around!
This topic is a grow journal. The recommended approach is not to “reserve” posts for future garden updates, but to update with new reply. This way you have the benefit of working timeline slider (on the right) in your journal.
Making some post a wiki (to be able to edit it indefinitely) is great for knowledge base type posts, seed waiting list, etc.
The decision is up to you obviously, I’m just recommending.
There could be also a mix of those two approaches. What you could experiment with is making first post a wiki and then adding a “TOC/Index” or quick links (linking to particular stages of grow, e.g. flowering, harvest) there as your grow progresses.