Both the Creo Herbam and Creo Terram guidelines are a bit sparse concerning thr repair of said objects (concentrating mainly on the creation).
What would be an appropriate level of Creo herbam spell, to repair damage to an object like a staff? How much for "severe damage" (e.g. almost hacked through)? Or broken (hacked in twain)? Or All-but-destroyed (in bits and pieces)?
Looking at healing spells (CrCo), perhaps a Base of 25 (fix a severed limb) is fine for rejoining the broken staff. And then a bit more for the bits and pieces.
Hmm, personally, given the raw material already present, I would use ReHe to fix a broken staff, maybe adding a Cr requisite depending on how sever the damage.
CrCo or CrAn spells can heal a living being, so you can use CrHe to heal a sick plant.
A wooden staff is made of dead wood, so you can't heal it. To repair an object you can use a Muto or Rego spell.
In Covenants page 99 there is a Ritual (Repair Cracks and Tears) that heals an animal-made product, so I think the spell you are searching for is related to Creo and Herbam.
In the Cr/He guidelines I found no obstacle preventing you to do that and because "plants may be created living or dead with equal ease" I suppose Cr/He healing spells could be right, but IMO you have to create at least a Level 20 Ritual in order to repair an item.
Frankly I don't see the value in pursuing a Cr ritual approach (takes longer to cast, costs vis) to fixing inanimate objects. Re(form) will achieve the same result much faster and with no vis.
The object only need be able to sustain the repaired state naturally for it to be permanent.
But if you were to snap a staff or other piece of wood in half rego magic could not return it to it's original condition. Rego could only repair the item as if a craftsman had worked on it. Creo on the other hand could return it to it's original condition as if it had never been broken.
(If the staff was enchanted there might be more to consider as the Verditious minor inner mystery of reforging seems to indicate)
I disagree wholeheartedly Erik. Rego magic can indeed manipulate two (or more) broken parts back together. It's simply using the existing halves and weaving the wood of the ends together. Since there is no breach of essential nature I have always personally considered this an extension of the term "control" target (i.e. controlling the very fabric of the object(s)).
My Verdi uses rego all the time to fuse his compounds items together.
Sure Creo can do the same thing, and if you'll note in my original response, I even suggested that perhaps a Cr req might be added to the Re spell if the break were so severe that parts of the original were missing.
I see no reason why one must limit themselves to Cr for a solution here and thus force themselves to spend vis when Re works just fine.
Broken pieces of wood can't naturally become a single unified piece of unbroken wood again so I don't think that rego is applicable. Of course I don't have books here to quote from in order to make my case by textural exegeses so I'm not going to pursue this disagreement with BoXer (and certainly no fewer than one of us is mistaken and I might well incorrect).
However I didn't mean to imply that creo was the only way to go about this. A muto spell that gives the broken staff pieces the ability to grow back together as a shoot could be grafted to a tree would be a fairly low level spell that would work to do the job (although perhaps a rego spell to control the growth so that the repaired staff resembles the original exactly might be in order).
Well it all comes down to a YMMV situation actually.
I consider the parts of the broken object not to have essential nature as broken pieces in relation to the true whole from when they were derived (if you get my meaning). Thus in repairing the object you are restoring the object to its essential nature as a staff. This would make the Re solution I posit to be perfectly viable.
Of course your suggestion of using Re to simply regrow the staff from a piece is viable as well.
The Mystical Carpenter (ReHe 25, Covenants p. 51) seems to indicate Rego can work just fine, if you're fine with it looking like it has been mended by a mundane craftsman.
If you want it back the way it was, seamlessly unbroken, I think that Muto or Creo would be The Way (TM).
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Answer tomorrow if I can check my books.