Candlestick plants (Senna alata) grow as perennials in U.S. Department of Agriculture plant hardiness zones 9 to 11. In colder climates, you can grow them as annuals. Candlestick plants grow to a height of 12 to 30 feet where they are winter hardy but usually reach a height of 6 to 8 feet in one season when grown as an annual. In either situation, they are fairly easy to grow and worth the minimal effort for their bright golden fall flowers.
Water newly planted candlestick plants as often as necessary to keep the soil consistently moist for the first month or two until they become established. Water them once every one to two weeks when the top 1 to 2 inches of soil become dry for the remainder of the season. Water candlestick plants only during extended dry periods after the first year.
Pinch the tips of new branches off in spring to encourage fuller, more bushy growth. Use sharp loppers or pruners to prune candlestick plants in the spring in warm climates where they survive the winter. Prune off branches that have been broken by winter weather. Trim all of the branches back to maintain a shorter bush, if you wish.
Check once per week for white chalky-looking leaf miner eggs on the bottoms of the leaves. Do this throughout spring. Scrape the eggs off right away. Leaf miners are tiny black fly, moth or wasp larvae. Prune off infested leaves which will appear discolored with pale green or brown squiggly lines from the larvae tunneling into them and eating the leaf tissue. Prune the entire branch back to beyond the last infested leaflet. Spray the entire plant, especially the bottoms of the leaves, with a ready-to-use insecticidal soap once per week in late spring and early summer if the infestation is severe.
Check the leaves for caterpillars and pick them off when you see them. Candlestick plants are rarely seriously damaged by caterpillars. If you prefer, you can leave the caterpillars to pupate and turn into butterflies.