As a nurseryman, I like things which are low maintenance and provide a long season of interest. Here I mention but a few plants which associate well in containers and also work well in the garden. This is by no means the opinion on this. There are MANY plants which work well in concert together, providing an eye catching spot of color for the garden.
Calylophus drummondii is a low spreading perennial with fine narrow leaves. It is almost continuously in bloom from spring to frost. Use it for trailing, or as a bright border edging. The yellow cups are bright and stand out among many other yellow colored plants. You can see this some distance away as its color is brilliant and goes on for so long. Purples, blues are classic combinations, but don’t forget foliage. Black, maroon, bronze foliage colors work well with this heavy blooming performer as well. If you like vibrant hot colors, this can provide that sunshine bright yellow and use orange and reds with it for a firery combination. As a container planting, use things like black leafed taro (colocasia esculenta ‘Black Magic’). In the garden, many of the purple things like Royal Purple smoke tree(Cotinus coggygria ‘Royal Purple’), bronzy Sambucus racemosa ‘Guincho Purple’ work nicely in combination, and provide vertical elements as well since they are shrubs. Abutilons are nice companions too, ‘Tangelo’, Victor Reiter’ are amazing oranges and also lend an air of tropical lushness.
Indigofera incarnata is a mouthful to remember, I usually tell people to call it the ‘miniature pink wisteria bush’ and they always remember that! It is very elegant, with pendant clusters of pink or white clusters in the wisteria fashion. Divided feathery foliate appears as an elegant foil to the flowers which have a long season. The bloom in spring, rest, then bloom again until frost. Nice thing to have at the front of the border, foundation planting, atop a retaining wall by a bench, anywhere you want a show stopper! The blooms are displayed to advantage in containers. They drape over the container sides and everyone always asks what that plant is. Easy care, water and feed lightly and that is about it, more sun, more flowers. Associates well with everything! A companion planting with Japanese maples is superb! Any plant that looks good with pink or white will look good with this.
Aloe ‘Johnson’s Hybrid’ is a low spreading perennial with constant bloom spikes. This is a short border type plant, of easy culture. You can even let it dry out and it will live! Bloom stalks come regularly and the leaves have the healing quality of Aloe vera. Flowers are orange tubes which hang down from the upright spikes. Many clusters appear all throughout the growing season until frost. Hummingbirds just love it. I have sold this to people that thought they never wanted a ‘cactus’/’succulent’ in their garden ever again! it is that good with those endearing qualities.
Calandrinia spectabilis is another plant of similar stature to the aloe. Low spreading growth (and it grows fast). This time you have slightly taller flower stalks which bear cups of magenta purple, each lasting a day, but many, many flowers come again and again. As the plant grows, more stalks appear, so the clump is quite showy for a very long bloom season. It is succulent in look with fleshy leaves, and is very easy to grow in sun. Think of it as a long blooming perennial poppy.
The flowering gingers are a large group which provide elegant foliage giving a tropical air and late season blooms which are often very fragrant in whites, pinks, yellows, oranges and reds. There are variegated forms of many and some are also edible(think Thai, Indian, southeast Asian cuisines). Humousy soil, fertilizer, and water yield lush results and the blooms delight with their often fragrant flowers. They also make wonderful cut material for the vase. Sun to shade(more sun, more water) but they are fast growing and the foliage in itself is ornamental. Variegated forms are splashed in white or yellow in striped patterns. Nice and different container subjects.