Deb, Questions, questions!!
Why are you doing the 4+ week cure? Is it due to your USDA zone? Have you had planters break due to freeze-thaw? Do you reenforce your planters? When's your last freeze/frost date? Are they putting this directly on the ground?

If your temps aren't staying in the 50's it's not a good idea to put it outside for curing. Ideal curing temps are between 50 - 75F.
You mainly need water in the first 5 to 7 days, look at Quikrete's web site or the Portland Cement Association's web site.

I think the problem, whether you wrap in plastic or not, is that it's too cold in your zone for a good cure.

I unmold in 24 to 48 hours(depends on the size of the planter) and place in a water bath for about 3 days then plant. Total time from start to finish is a week to a week and a half. Been making them for over 20 years now. Billie

Hmmm Billie...good questions

I have always given them a long curing time as my understanding is that the longer the better w. anything w. cement in it...and yes it is mighty cold here in the winter...I have had good luck wintering over planters as have my customers...I have never made one big enough to have to reinforce,,,have only lost one, maybe two and perhaps a moose stepped on it..who knows!

It sure is still being below 50 here most nights in May. Would wrapping them keep a little warmth in them since they are going to be filled with soil? I don't know! Possibly.

I think that probably it's going to be fine. It is reassuring to hear that your total time is a week. So 2 1/2 weeks is not bad.

thanks

Yeah, it's hard to moose-proof your planters...lol!! That's funny, I thought we just had to worry about our different temperature zones when giving suggestions/help. That's why it's nice if people list their USDA zone.

From different classes I've taken I believe the strength was approximately 75% by 7 days and 90% by 28 days. Most of this information is for large concrete work not the smaller pieces that most people make on this forum. Funny people worry more about this than adding too much water to the mix. The drier you work the stronger the mix.
Anyway, wrapping the planter will help. I've used bubble wrap then put burlap on top of that. I've hollowed out a bale of straw and placed a planter in it for the Winter. This was more to protect the roots of a tree than protect the container. Just tell them to be gentle cause it's still green. Keep us posted how it turns out. Billie

I'm a newbe here and haven't even made anything yet, but if it's going to be under ground at a cemetery where they water the grass every couple of days, I would think it would stay damp, hence more curing. No? NT

NT, Don't know about other parts of the country but in Pennsylvania we leave our planters (in cemetaries where it's allowed) next to or in front of the headstone. We also don't water our cemetaries. Do they really water the cemetaries in California?
DEborah, Did the people pot up the planter? How's it look? Billie

Well, here in CA we rarely get any rain from April or May until October or so!
They HAVE TO water the cemetaries or they turn to dust!
That's why I mentioned that the place would be well watered.
You guys back East get rain all the time! I'm jealous!