Pelargonium x hortotum. Black Velvet Rose Geranium seeds should be started indoors in early spring. Once the weather warms up in late spring to early summer, and night time temperatures are steadily above 10°C (50°F), the curious little seedlings can be transplanted outdoors. Expect dark, nearly jet-black foliage with each leaf marked by a light green margin. Above the unique foliage rise clusters of florets in bright rose pink with white centres. This hybrid geranium has robust growth and a nicely mounded form that is heat tolerant, and well suited for container growing, so it’s a superb choice for patio gardens.