I'm a newbie gardener and I wanted to rework the existing plants in the backyard of our new house to create a small corner garden along our back fence. It will end up to be the shape of a quarter circle, about 8-9' in length along the 2 straight sides. I have a little room to go longer on one side if need be, but not too much longer since we want to put down a patio next to the small garden.

Currently, the plants that came with the house include:

-Hibiscus, which takes up that back corner space, and a spirea bush along one side of the fence (pretty much takes up the length of the fence). The rest of the area is empty (the plants are currently spread out over a 15' narrow strip).

-3 Little spire Russian Sage plants

-3 Salvia 'May Night'

-3 Gaura lindheimeri 'Blushing butterflies'

-6? Rudbeckia (I think, I can't tell yet, they're just starting to come up...probably the Goldstrum)

-9 Asiatic lilies (yellow-orange)

-6? Irises - purple

-three random plants I got as a freebie from another plant order (1 achillea coronation gold, 1 guardilla 'oranges and lemon', 1 rudbeckia moreno)

My problem is that everything is either purple or yellow (except for the gaura) and approximately the same height. I'm not sure how to fill in the rest of that semi-circle without it looking too much like a checkerboard. I would prefer not to have to buy additional plants since we spent a fortune on our front yard garden this year.

If you have made it through this entire post and have any ideas to offer, I would be most grateful!