Although the idea of mason jars with plants in them sounds cute, without drainage you will have a hard time getting anything to grow in such a situation.

May I suggest that you find some already mature or even blooming plants in June in pots small enough to sit inside the mason jars that you have. Fill the mason jars with gravel or glass marbles or peat moss or anything and then set the potted plants inside that.

Joe

Love your idea! My brother and his wife used the kind of container from chinese take-out [new] with suculants grown in soil. I wonder if you might use the same kind of container with sweet alyssum or lobelia. They are not natives, but naturalize very well, and would look well in small containers. I believe I've seen small lunch sacks used for this kind of table decoration ... cut down to size with pinking shears - line with plastic bags?
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I found this nursery while looking for something else. They sell only CA natives ... you might find just the right plant[s] already started and super easy to use for your table decorations.... hope so. Is Santa Margarita up your way? [San Luis Obispo ?] Mail order, or 'road trip' down to pick them up?

http://www.laspilitas.com/

They won't be in bloom necessarily, but a succulent such as a chalk dudleya would work in a container and has an attractive shape. Drainage will be important, so the mason jars wouldn't be a good long term home for them.

Yeah, the only native I can think of that would be small enough is the dudleya, as kelpmermaid suggests. You could fill the bottom of the Mason jar with gravel and put soil on top; that would look really pretty on the tables. They could be easily pulled out and put in the ground later.

There might be some native ferns that are small enough- how about maidenhair ferns?

Renee

Live oaks,Garrya-in bloom now with its distinctive silk tassles,Vine maple,California Buckeye is a sculptural in leaf and out of leaf. Ribes sp. All these and more take container watering...
Chain fern is another great (big) container plant,Coral bells..at native nursery I would hunt for Catalina coralbells-huge leaves and blooms.Fremontodendron is a beauty.
If you want native succulents -the golded spined teddy bear Cactus is the beauty of them all in my opinion.

Really, also almost any native shrub that does well in part shade can take all year watering in a pot. So,you could be creative and keep Alders,Willows and yellow in autumn leafed, Cottonwoods with black trunks-when wet.

Thanks all! We aren't necessarily wedded to the idea of the Mason jars and could just as easily do small terra cotta pots, but it seemed like it the jars might be easier logistically. Either way, sounds like the way to go is to either grow or purchase the plants separately and transplant them a day or two before, though. I'll take a look at some of these plants---thanks for all of the suggestions!

Not "wedded" to the idea. Yuk yuk.

oop,I must have skipped the extra small container part...but,creative could still be native tree's almost Bonsai'ed. Believe it or not, I have kept live oaks and buckeyes in 6" pots for years-near a decade now. And they still send out long shoots that I prune back to a nice form-healthy plants.