Rex Begonia Plant Care: How to Grow Rex Begonias

Rex begonias (Begonia rex-cultorum) are cultivated herbaceous perennials that grow from rhizomes, a type of plant stem that grows horizontally underground or across the soil surface. Also known as painted-leaf begonias, this semi-tropical plant blooms tiny flowers and is most notable for its distinct leaves that grow in diverse shapes with unique patterns. While some leaves are heart-shaped with silver streaks, others have jagged edges with swirling pink designs.

Rex begonias are versatile plants that you can grow indoors or outdoors: Its colorful leaves make for an elegant houseplant or addition to a terrarium. To grow begonias as an indoor plant, select a wide, shallow pot with drainage holes, fill it with porous potting soil, and place it near an east- or west-facing window. As the rhizomes grow to the side of the pot, prepare for repotting.

Hundreds of begonia cultivars and hybrids offer unique, variegated leaf patterns and colors. Here are some of the most common:

1. 1. ‘Angel Wing’: This begonia cultivar grows long, dark-green leaves covered in silver spots alongside red blooms. An upright-growing variety, ‘Angel Wing’ can grow up to two feet tall.
2. 2. ‘Charm’: This begonia cultivar features bright green leaves with showy pink streaks. This begonia type grows outward instead of upward, creating dense foliage coverage.
3. 3. ‘Escargot’: The spiraling leaf pattern on this cultivar resembles a snail shell, beginning at the center of the leaves twirling out toward the leaf tips. The leaves are a mix of green, silver, and brown and grow alongside pink flower blooms. This cultivar grows spiraling out and can reach a height of one foot.
4. 4. ‘Plum Paisley’: This cultivar grows dark green leaves covered in stripes of lavender and speckles of silver. It prefers hot temperatures and high humidity and grows low and wide, spanning about four inches tall.
5. 5. ‘Red Kiss’: The ‘Red Kiss’ cultivar is a vibrant, medium-sized option with bright red and black leaves that grows between six to eight inches tall. While the leaf colors dull in the heat, the color increases in vibrancy as the temperature cools.

Rex begonias grow best in USDA Hardiness Zones 10 and 11 and thrive in moderate humidity and partial shade between sixty-five to seventy-five degrees Fahrenheit. Here is a step-by-step guide on how to plant rex begonia seedlings in your garden:

1. 1. Obtain seedlings. Microscopic rex begonia seeds are difficult to see, let alone handle, so the best way to grow the plant is from seedlings or propagating from a leaf cutting. You can purchase seedlings online or at garden centers and nurseries.
   
2. 2. Choose a site. The rex begonia plant grows best in shady areas, as direct sun can burn the leaves. Bright indirect light promotes plant growth, preventing root rot and providing the leaves with sunlight in small doses. Find a site that receives minimal direct sunlight and good water drainage, like under a tree.
3. 3. Prepare the soil. Begonias prefer slightly acidic soil, with a pH between 5.7 and 6.2. Loosen the soil with a garden rake or your hands. Dig holes about seven to ten inches apart to give the seedlings ample room to grow. Learn how to test soil pH.
4. 4. Plant the seedlings. Place the seedlings into the holes, then gently cover them with soil.
5. 5. Water the soil. Settle the soil with a generous watering, which will encourage the seedlings to root.

Rex begonias enter a dormant stage during the winter months, which will cause them to shed their distinct foliage. However, by springtime, you’ll have new growth that only requires minimal plant care.

1. 1. Fertilize the soil. During the growing season, fertilize the soil twice a week with diluted water-soluble fertilizer. It’s also important to ensure the soil is well-drained. While begonias prefer moist soil, the plant is prone to root rot. Add perlite or peat moss to the planting area to aid drainage.
2. 2. Water the plants weekly. Water your begonias about once a week when the soil is dry to the touch. Avoid overwatering and misting the leaves with a spray bottle, as this will cause mildew and lay the groundwork for root rot.
3. 3. Monitor the plant for pests. Both mealy bugs and powdery mildew commonly affect begonias. While the plant can tolerate minimal mealy bugs, large infestations will inhibit its growth. Powdery mildew results from damp leaves and spreads quickly, so treat it with a fungicide at first notice. The plant is also susceptible to botrytis fungal infections, or gray mold. To prevent this fungal infection, remove dead leaves and ensure the plant has good air circulation.

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