Ron,

Wave petunias will grow over non-invasive grass, but might have a problem competing with Bermuda, and possibly St. Augustine. In order to save money, you will want the ones that spread the farthest. The original Wave or the Tidal Waves are probably best for your use. You could space them about two feet apart and let them fill in. The Shock Waves don't spread so much and the Easy Waves are taller and not so spreading. The Wave plants are relatively expensive and even the seed is fairly expensive. For more info, see the Wave Family web site. Of course, the Waves aren't the only seed-grown spreading petunias. But they are probably the most popular. I have heard that some spreading petunias can spread as much as 8 feet. But I can't confirm that, because I am not a "petunia person". Zinnias are more my thing.

ZM

Quite a pretty picture you painted there--flowers cascading down a grass filled slope.

The reality is grass grows--you can't mow because of the flowers, your flowers will be hidden by tall unkempt grass. Then you will have to go with clippers and cut the grass. My prediction--the flowers will be yanked out before the summer is over

I use Easy Wave a lot to fill in areas, it always does very well for this purpose. But I have found that for some reason the "Blue" Easy Waves seem to spread a lot better than any of the other colors...I wonder why that is? Anyway, the Shock Wave series isn't very good,IMHO. I got some Ivory Shock Waves last year, and the flowers were much smaller, they got leggy and didn't really spread at all. I have never tried Tidal Waves or the Original.

I agree about the blue Easy Wave. It is the best at spreading.

Look into supertunia's... they are kinda pricey as well, but you cant beat the size and flower power ;)

note: white variety stays VERY close to the ground. Also expect several feet of width on these ladies (mine attained about 3' in width almost 4'), and maybe 14"ish tall, at least that's what i observed mine.

how will you water the small babes while the super aggressive lawn steals all the water????

i also agree... that un-mown lawn.. will be 1 to 2 feet tall by july .... and your flower show will be limited ...

if it were me.. i would round up the grass in swales, as soon as possible .... say mid april .. and then adding 3 inches of mulch ... and then planting right into the dead grass ... when the frost issue resolves itself ....

ken

I read this posting and had to do a double take because my neighbor asked me to do this same thing for them. A large lawn area they were sick of mowing and wanted petunias to cover the sloped area. I covered the entire area with newspaper, at least 10 sheets thick everywhere and then added 3 inches of city (free) mulch to the area. The newspaper kept the grass at bay and the mulch kept it in place. I then palnted Tidal Wave petunias every 2 feet. The closer you plant TW the taller they get but at 2 feet they spread enough to cover the mulch late June. It was beautiful! I did have to ammend the soil where I planted the little guys and it paid off. The few plants I just planted in the ground without better soil, were a beast to keep watered. And then the more you water the more mildew shows up.

So in saying that, if you just plant petunias, no matter what kind, they will lose the battle to grass. They will also need A LOT of water and then form mildew if you don't water only at night. So it is not really worth it unless you kill the grass by smoothering it or removing it.

My long winded 2 cents

Keriann~

What about daylilies? They would tower over the grass with no effort.....and then maybe a border of petunias in the front. You would have to remove the grass in the petunia border but then in the fall you could mow the daylilies and and grass that is left?? hmmm.. I might have to do that for my side garden this year.

Happy Gardening!

Keriann~

I wouldn't plant any annual over grass. If you are successful in getting them to grow, you'll have to hand weed the grass growing up through them. More likely the grass will win if you don't deal with it first. If you lift up any stand of healthy grass you'll notice that the blades of foliage are just part of the picture. It often has some thatch, and a tightly knit root system going down several inches. This in itself limits the penetration of water to as deep a depth as cultivated soil.

I have covered hillsides in annuals and also perennials, but I have terraced them or used perennials to hold the soil so it wouldn't erode in winter when the annuals die off. Spend a little time to prepare the site before you consider this. That means removing the grass and cultivating. It will save you work in the long run and you'll get better and more long-lasting results.