How to Grow and Care for Coleus (The “Collis Plant”)

Coleus plants are celebrated for their vibrant, diverse foliage rather than their flowers. These versatile plants, belonging to the mint family (Lamiaceae), feature an impressive array of leaf colors, patterns, and shapes. They are a popular choice for both indoor and outdoor gardening due to their striking appearance and ease of care. Coleus offers season-long visual interest until the first frost, whether used as bedding plants, in containers, or as houseplants.

Coleus Plant Care

Light

Coleus plants thrive in specific light conditions that significantly influence their foliage color. Many varieties flourish with morning sun and afternoon shade, which helps maintain vibrant colors. While some newer cultivars tolerate full sun, too much intense, direct sunlight can scorch leaves or fade their colors. Insufficient light can lead to duller colors and leggy growth, indicating the plant is stretching to find more illumination. For indoor Coleus, a bright, indirect light source is ideal.

Water

Coleus plants prefer evenly moist but not waterlogged soil. Allow the top inch or two of soil to dry out between waterings to prevent root issues. Overwatering can lead to root rot, while prolonged dry spells can cause leaves to brown or the plant to wilt. Outdoor potted Coleus may require daily watering, whereas indoor plants need water once or twice a week.

Soil

Coleus plants perform best in rich, loose, and well-draining soil with a pH between 6.0 and 7.0, ranging from slightly acidic to neutral. For container planting, use a good quality potting mix with adequate drainage holes to prevent water accumulation and root rot. Amending garden soil with compost or other organic material improves both fertility and drainage.

Temperature and Humidity

Coleus are tropical plants that thrive in warm, humid conditions. They should not be planted outdoors until temperatures consistently remain above 60°F (15.5°C). Optimal growth occurs between 75°F and 90°F (24-32°C), and temperatures below 50°F (10°C) can cause damage. For indoor plants, maintaining humidity levels between 50% and 70% is beneficial.

Fertilizer

During the growing season, Coleus plants benefit from regular feeding. A balanced liquid fertilizer applied once a month is sufficient for potted plants. For in-ground plants, amending the soil with compost provides initial nutrients, and light feeding with a water-soluble fertilizer every 6-8 weeks is recommended. Over-fertilization can suppress the vivid colors of the foliage, so follow dilution directions.

Propagating Coleus

Cuttings

Propagating Coleus from stem cuttings is a successful method. Select a healthy stem section 4 to 6 inches long, cutting just below a leaf node. Remove all leaves from the lower half of the cutting. Cuttings can be rooted in water by placing them in a glass jar in a bright location out of direct sun. Alternatively, plant cuttings directly into moist potting mix, with rooting hormone optionally applied, and cover the potted cutting with a clear plastic dome or bag to maintain humidity.

Seeds

Growing Coleus from seeds offers a wide variety of unique patterns and colors. Start seeds indoors 8 to 12 weeks before the last expected frost. Coleus seeds are tiny and require light to germinate, so sprinkle them lightly over moist potting mix and gently press them into the surface. Maintaining a soil temperature between 70°F and 75°F (21-24°C) is ideal for germination. Once seedlings develop their first true leaves, transplant them into individual pots.

Popular Coleus Varieties

Coleus plants exhibit an extensive range of varieties:

  • The ‘Wizard’ series is known for its smaller, branching form and standard color mixes, suitable for containers and hanging baskets.
  • The ‘Kong’ series features expansive leaves, up to 6 inches wide, on plants that can reach 2 feet tall, preferring shade to prevent leaf burn.
  • The ‘ColorBlaze’ series offers upright, heat-tolerant varieties adaptable to varying light conditions, showcasing deep burgundy or vibrant red foliage that intensifies with more sun.
  • ‘Chocolate Covered Cherry’ displays colors from pink to burgundy with green edges.
  • The ‘Premium Sun’ series is bred to thrive in full sun.

Common Coleus Problems

Coleus plants can encounter a few common problems. Pest infestations can cause stunted growth or distorted leaves. Common pests include:

  • Aphids
  • Mealybugs
  • Spider mites
  • Whiteflies

A strong spray of water can dislodge some pests, while insecticidal soap manages severe infestations.

Fungal diseases, including downy mildew, root rot, and stem rot, also affect Coleus. Downy mildew appears as fuzzy gray or purple spores on leaf undersides. Root and stem rot are caused by overwatering or poorly draining soil, leading to wilting and discolored leaves. Ensuring good air circulation and avoiding overhead watering helps prevent these issues.

Other common issues include leggy growth and wilting. Leaf discoloration may indicate light imbalances or nutrient deficiencies. Adjusting care practices can resolve these problems, promoting healthier Coleus plants.

How to Grow and Care for Rose Mallow Hibiscus

Benefits of Having Tillandsia in Your Home

How to Grow and Care for Tradescantia Minima