Well, I'm another Californian with hot dry summers. But I grow a lot of irises, all kinds of lilies, dahlias, salvias, dianthus, foxglove, peonies, clematis, centaurea, pelargoniums, echinacea, snapdragons, guara, echinops, hellebores, heucheras, alstromeria, glads (altho they don't do that well), african daisies, asters, mums, euphorbias, gazanias, gaillardias, gerbera daisies, marguerites, rudbeckias, penstemons, shasta daisies, tracheleum caeruleums, lion's tail, verbascums, veronicas, lavenders, scabiosa, lantana, eucomis, caryopteris, stachys.... The best of them are the dianthus, echinops and lilies. The irises have to be thinned out about every three yrs or they become invasive and quit blooming. Salvias can get overwhelming. I have three "Hot Lips" in one bed and by summer's end they engulf the whole bed. The tracheleums are lovely, but they also get huge and spread all over, and have to be deadheaded. Asters and mums have to be hard pruned and thinned. Same with Shasta daisies. Euphorbias get really innvasive too, but they make nice fillers, until you have to deadhead. Snails and slugs like the gerberas. Dahlias have to be staked, or they become trailing groundcovers! Dang I hadn't realized just how many different plants I have put in the yard.. Not to mention the many Japanese maples and butterfly bushes, azaleas, camellias, rhodies, daphne, witch hazel, pieris japonica, etc all in the shady areas. Yikes.... Now, if I could just get delphiniums to grow!....

Some marigolds DO work against nematodes; I have seen the results myself, comparing roots of tomato and pepper plants that were thickly underplanted with marigolds with roots of plants that had few or no marigolds nearby. But as I said, the marigolds have to be thickly underplanted (completely surrounding the tomato plant and quite close to it) to be effective. That means they are competing with your tomatoes for moisture and nutrients. Also, tall varieties of marigolds can outgrow and completely overwhelm a young tomato plant. Another way to use marigolds for nematode prevention is to grow a dense cover of marigolds in your tomato area the season before planting. That should drive off the nematodes for a few months and give your tomatoes a good shot. Of course, that means you're not growing a crop in that area for a few months while the marigolds are driving off the nematodes. If nematodes are not a concern, I second the recommendation for basil. Basil and tomatoes get along as well in the garden as they do in the kitchen. If you let it flower, the basil will bring bees into your garden, too.

These are some of my Salvia combos - S. clevelandii 'Allen Chickering' grouped with both Vitis californica 'Roger's Red' [CA wild grape, which currently has the red leaves of autumn] and S. azurea var. grandiflora. S. coccinea 'Lady in Red' with S. guaranitica 'Black and Blue'. (Intense!) S. darcyi grouped with a dark brown/pink/tan?-striped Phormium hybrid [flax] and S. 'Indigo Spires'. S. farinacea 'Rhea' grouped with an orange Arctotis hybrid [African daisy], S. 'Nuevo Leon', Pennisetum setaceum 'Rubrum' [fountain grass], S. officinalis 'Purpurascens', and a cluster of faded orange Chrysanthemums. S. greggii 'Teresa' with Cistus x pulverulentus 'Sunset' [rock rose]. S. x jamensis 'Sierra San Antonio' growing up through a sea of Lantana montevidensis. S. mexicana 'Limelight' with S. microphylla 'San Carlos Festival' spread at its feet. (This is a new planting, so we'll see how it goes.) S. nemorsa 'Caradonna' with Sedum telephium 'Matrona' [stonecrop], as suggested by Betsy Clebsch in her book -surrounded by more of the Lantana. :) S. elegans with S. uliginosa and Hebe x franciscana 'Variegata' (the purple blooms of which occur at a different time of year, so as to prevent any clashes). I just realized how much I typed. Too much coffee. :D Brenda

It is a great site to get ideas isn't it? :-) Civil Servant my zone is so much different than yours that anything I recommend may not work in zone 5, but that site has a lot of ideas for different regional areas: https://www.gardenia.net/plant-combinations Some plants that I think look great with roses and also like colder weather (but don't do so well for me here we're its hot.. and I always covet them) are peonies and Johnson's Blue geranium. The blue/purple geranium trailing through the roses would look great with each color! I'm sure there are a lot of other ideas on that site too. :-)