I don't see anywhere in the book where a charge item cannot have duration Sun and a constant effect. As such as covenant background flavor I created this:
Flower Pots of Euanthia
by: Euanthia the Tenderest Shoot
description:
With greatest of love for all growing things, Euanthia created hundreds of pots in which to grow her beloved plants. Each pot is a simple charge item and yet the magic has lasted for over a century. The legend says that as long as plants grow in Porphyris, Euanthia will bless the people.
The pots are charged items which casts a simple spell to ensure the plant within the pot grows healthy and hearty during its life within the pot. Of the many pots made by Euanthia, only three dozen remain, collecting dust in the collapsing apothecary house.
item level:
8
spell:
Euanthe's Blessings Cr/He level 4
effects:
base 1 to make a plant grow healthy, +1 touch, +2 sun, +4 for constant effect
activation:
the only action required to make the charge item work is for a plant to be planted within the soil of the pot
It'd still eat up a charge everytime it was activated, and in order to keep it 'constant' it'd burn through 1 every 12 hours or so (dawn to dusk, dusk til dawn, etc.).
Doable, yes. Effective, not so much. Not counting warping.
That said, I'd have to double check to verify your example. Might be one of those odd guidelines that takes (duration) to happen but the effect is permanent.
Constant Effect Devices, as described on ArM5 p.99 box, specify two uses per day for the effect. By ArM5 p. 96, a "charged item can be used as desired until the charges run out", and has no uses per day.
But perhaps Euanthia IYC made a breakthrough?
Give them duration and target circle. The pot itself is the circle. Planting something activates the charge, and until that thing is removed it gains the benefit.
Won't work. To trigger a duration ring target circle, a magus must trace the circle if it is premade, or actually draw/walk it (depending on scale) if it isn't.
Though TBH, I want NOTHING to do with your warped plant whatsoever, OP.
Make it D:Conc. + Item maintains concentration. It can be permanent that way.
I have to say we have a few permanent items with Circle ring parameters. They are far from game breaking, we would say. But yes, it is house rule territory. In the same way that it is impoosible for a mundane to use an item to draw a circle/ring if you apply the rules strictly, since it must be a magus the one drawing the circle/ring.
I had a game last night where the villain had a spell of ring duration with a ring set I masonry that fell after 200 years when the hero's collapsed the tower it was in- so ring may be enduring if established well, but not truly permanent. (villain was a Diedne who escaped the march by turning herself into a living ghost and staying hidden, the circle spell forced other spirits to manifest so she could summon them into the circle and harvest them for vis)
Indeed, IIRC, concentration items actually require the user to concentrate for a short time at dusk and dawn to maintain the effect since the magic in question flickers otherwise.