Ask Mr. Smarty Plants

Roses are interesting plants. They are not fussy per se, but there are some rose rules that are good to keep in mind when planting companions. It's a little bit like adding a puppy to a house full of cats, you want to make sure everyone will get along. 

Roses don't like other plants touching them. They also don't like to get their leaves wet when watered. They respond well to fertilization, but at specific times and temperatures. Although they don't want to be watered from above they don't like having their feet wet too long, so good drainage is best. Roses like their soil just right and if they are lucky it is the texture of a good chocolate cake. In Texas they don't like too much mulch, but do want some. If you took your roses out to breakfast and the waitress asked how they wanted to have their eggs prepared, they might respond "perfectly". They also would like sunlight from all directions. Other than that they play well with others. So consider these things when adding your new charges. It isn't hard once you have everything in the ground. All you have to do to find good natives that share in the same growing conditions. 

Don't choose plants that will become too bushy and brush up against the rose or block any light. Roses respond well to having their feet in the shade so a ground cover would work as long as the base or stem of the rose is not covered completely. When that happens, they can stay too wet at the base, after a rain or a watering. This can produce stress or in the worst cases rot.

Living in east Texas, you have an abundance of good choices. If you use the plant database on the website you can look for plants that do well in your area and can further sort by color, to find your requested blue, white, pink and yellow. Play with the different searches and when you find plants you like, read about their care and requirements to make sure that they have the same basic needs as your roses. Here is a small list of plants that would work. There are plenty more to choose from but this will give you some tips to help you think about the placement of plants as well.

If your Knockouts are spread apart and you would like to have plants in between them, then from the roses, radiate out, with smaller plants that will never get bigger than your roses in height. Columbines would work nicely close to the roses. They are small and will never crowd. Aquilegia chrysantha (Golden columbine) is a yellow native to Texas, although it is found in the wild, in west Texas. It would do fine where you are, with the condition that you make sure not to overwater it. The columbine which naturally occurs in east Texas is Aquilegia canadensis (Eastern red columbine) a red variety. Phlox divaricata (Wild blue phlox) would also work well close to the roses. These are a small wild blue phlox, they like the same rich soil and they would love to be planted right under the roses to give them a bit of shade. They too, do not like to have their feet wet too long so you could water them exactly the same as you would a rose. Tetraneuris scaposa (Four-nerve daisy) would be another option close to the rose that gives you some yellow. 

As you move out from under the roses you can go higher with the companion plants. You want plants that don't get too bushy so think about an upright shape as being a good choice for the middle areas between your roses. Irises work well here. There are many varieties so take a look in the database and see which ones you like best that will work for your area Iris virginica (Virginia iris) would be fine in east Texas. Liatris elegans (Blazing star) would also be a nice vertical addition with the Iris or alone with the roses. They aren't exactly blue but more purple/pink/blue. Even though Iris and Liatris are vertical, they both spread with rhizomes so you have to thin out the clumps they produce over the years so rhizomes don't crowd the rose roots underground. Both make great cut flowers so don't forget to add them when you are cutting a bouquet of roses. 

As you radiate even farther from the roses you can be less concerned about over crowding. Conoclinium greggii (Gregg's mistflower) is a must for any Texas rose garden. The mass of blue flowers all covered with butterflies mixed in with Knockout roses would be a stunning display. This plant spreads with just-underground runners and can double in area, in one season. They are easy to control, by pulling out any that have spread too far. The roots are shallow. This is a great butterfly plant and will draw pollinators to your garden. Symphyotrichum oblongifolium (Aromatic aster) is a native to your own backyard in terms of its natural range in Texas. This fall blooming aster is a nice batch of blue blooming later than the rest. This too spreads so make sure to plant this on the outskirts of your beds. 

Your desire for white in the beds can be combined with you're wanting of ground cover. Phyla nodiflora (Texas frogfruit) is just about the cutest white ground cover you will ever see. Frogfruit isn't aggressive and it doesn't smother plants the way other ground covers tend to do. It will ramble politely between plants looking for open patches of light and ground. It will climb rocks but will stay off plants. It blooms often, from early spring until late summer and into the fall. It might die back a bit in the winter depending on the season but is a tough little plant and can take a lot of water or hardly none at all. Frogfruit might be a perfect plant to tie everything together.

You can easily become carried away when planning a garden. We have probably given you more to think about than what you had bargained for, so take some time and hunt around in the database. You will find plenty more options to choose from. Roses are a great centerpiece to a Texas garden. Have fun with it.