Hard to tell from the pic, but looks like they may be a little too dry -- make sure to keep an eye on the watering. Also, I would move them closer together if a filled-in look is what you're after - if you just recently planted them, popping them out and replanting shouldn't be any big deal. Did you fertilize when you planted? I like to sprinkle Osmocote (timed-release fertilizer, once and done for the season) when I plant.

they will start spreading when the roots settle and get established enough ... and i really dont think fert is going to speed up recovery of transplanting stress .... and in fact.. i would let them get over that stress.. before i used fert.. just to make sure i didnt shock them more ...

when did you plant them ... most things do seem to just sit there for a week or 3 ... they are growing roots you cant see.. so it seems like nothing is happening ...

i also think it looks real dry .. try to water the whole bed.. rather than just those planted.. to encourage the roots to spread ...

i dont understand what the pot has to do with the bed.. other than it looks like they have been in that pot a couple weeks longer than those in the bed ... but if not.. then you are watering the pot more efficiently than mother earth ...

ken

From what I understand, the Wave Petunias are the ones you want for your flowerbed. They spread & are easy to grow. Petunias are heavy feeders and should be fertilized about once a week, but get a fertilizer for blooming which is usually safe. You don't want a fertilizer that produces growth with no flowers.

Always fertilize after you water the plants. Since your plants are young you may need to water twice a day if it's hot.

I agree with Mxk, move them a lot closer, or better yet, go to a nursery and get some Wave petunias to fill in the spaces. A rule of thumb for me is never go by the directions on how close to plant flowers. I plant them a lot closer. lol.

Good luck! I'm in Z7 and the heat gets to mine so I stopped growing them.

I planted wave petunias in full morning sun almost 3 weeks ago and they don't seem to be spreading much either. Waiting patiently...

Oh, it takes awhile, usually around mid summer is when plants put on a real show.

I am having crazy awesome luck with Proven Winners supertunias, specifically Vista Fuschia and Bordeaux supertunias. Waaaaaay better than I ever had with waves. I have put ONE plant in each of my 14 inch pots, they are all overflowing and growing down the sides!

On Mondays, they each get Jack's Petunia Feed, on Thursdays they get root and bloom boost. Every other Sunday they get Seedlinger's Fertilixer. Once a month, each pot gets a wetting agent. Because yours are in the ground, you could probably cut way back in the schedule, like half as often.

Sorry the photo was in the dark, I just ran outside to get a current photo. This was planted four weeks ago, again, it's only ONE plant...

Here is another supertunia, planted in the ground. This was three weeks' growth on a Pretty much Picasso. I didn't give it nearly enough room. I only fertilized it twice, but next time I'll switch to the root and bloom boost. I'll have to give them much more room next year...