30+ Hollyhock Black Malva Flower Seeds, Alcea Rosea Carnival, Self-seeding Biennial, Decorative, Blooms Heavily, Attracts Bees and Hummingbirds! From USA Hollyhock Black Malva Flower Seeds, Alcea Rosea Carnival, Self-seeding Biennial, Decorative, Blooms Heavily, Attracts Bees and Hummingbirds! Annual. Height: 5-6'. Depth: 1/8". SOIL temperature MUST be kept at 70F for proper germination!!! Cool soil, particularly at night can inhibit or significantly delay germination. Overly warm soils, well above 90F, can inhibit germination and provide ideal conditions for seed rot. To keep soil temperature warm, start seeds indoors. Keep the container covered with a plastic bag on the top of the fridge where the room temperature is higher, therefore the soil temperature is good for germination. Keep soil moderately moist, though not overly, dripping wet. Water soil when the soil surface just begins to dry. Once seedlings have sprouted, keep in small containers until a few sets of leaves have developed. Transplant to larger containers or outdoors. Soil Type: Well drained, pH 6.1 - 7.8.