Annual
Coleus
Coleus scutellarioides · Lamiaceae
Also called: Painted Nettle, Flame Nettle, Solenostemon scutellarioides (former name), Plectranthus scutellarioides (former name)
Coleus (Coleus scutellarioides) is a moderate-water annual well suited to Tucson and the low desert. It's a fast-growing annual.
Coleus at a glance
- Water use
- Moderate (established)
- Sun
- Part shade to filtered light; in Tucson, morning sun with afternoon shade or bright dappled shade is essential—full low-desert sun scorches the foliage. Sun-tolerant cultivars handle more light with steady moisture. Also grown as a houseplant in bright indirect light.
- Mature size
- 10-24 in tall and wide (varies widely by cultivar)
- Growth rate
- Fast
- Bloom
- Insignificant pale blue to lavender flower spikes (grown for vivid multicolor foliage), Grown for foliage; small blue/lavender flower spikes appear in summer and are typically pinched off
- Cold hardiness
- Very frost-tender; damaged below ~50 F and killed by frost. Grown as a warm-season annual outdoors in Tucson or year-round as a houseplant (min. indoor temp ~55-60 F).
- Soil
- Rich, moisture-retentive, well-drained soil; amend lean Tucson soil generously with compost. Containers with quality potting mix work very well.
- Native range
- Southeast Asia and Malesia (tropical Asia to Australia)
- Best used as
- Shade-garden foliage color, Container and hanging-basket plantings, Patio and covered-entry accents, Houseplant (indoor color)
- Wildlife
- Low wildlife value; flowers attract some bees and hummingbirds if left to bloom. Generally not browsed.
- Toxicity
- Toxic to dogs, cats, and horses (ASPCA-listed)—contains essential oils/diterpenes (coleon O) that cause vomiting, diarrhea, drooling, and possible skin irritation. Keep away from pets; sap can irritate sensitive skin in people.
How to grow Coleus in Tucson & the low desert
Watering
Warm-season annual: plant after frost (April) in a shaded spot. Keep soil consistently moist—coleus wilts quickly when dry, especially in dry Tucson air and heat; water frequently (often daily for containers in summer). Mulch and group plantings to raise humidity.
Fertilizer & nutrients
Moderate feeder for lush growth; apply balanced slow-release fertilizer at planting and a diluted liquid feed every 2-4 weeks during the growing season. Avoid excess nitrogen, which fades leaf color.
Pruning & care
Pinch growing tips regularly for bushy, compact plants and remove flower spikes as they form to keep energy in the colorful foliage.
Notes
In Tucson, treat coleus as a shade/container plant—it cannot take full low-desert summer sun and dry heat without scorching. Excellent for shaded patios and north/east exposures, or grown indoors in bright indirect light year-round. Roots easily from cuttings to overwinter indoors.
Sources: University of Arizona Cooperative Extension; Pima County Master Gardeners; ASPCA Toxic Plant Database; Missouri Botanical Garden