Viall's primrose

Plants for partial shade need a few hours of direct sun per day to grow and blossom properly, thus could suffer harm from direct sun heat or overlong sun exposure. It is important for the plant not to be exposed to afternoon heat and in early afternoon hours, but must be exposed to morning, forenoon and evening sun. Partial shadow position can mean a site that is sunny one part of the day, or a site with sun and shade in patches, as it is the case under broadlived trees or behind a picket fence - wooden boards with spaces in between.

Herbaceous plants are not woody. Their stems are soft, usually remaining green. With some herabceous older stems may harden and look like woody stems (e. g. bamboo).

The plant develops new leaves or needles every spring, which dropp off in autumn. Herbaceous plants can die completely in above ground section and grow back in the spring.

Plant can in otherwise appropriate environment survive cold down to - 23 °C.

Moist soil usually contain morefine clay parts and less sand, more humus and organic materials, they are somewhat heavier, but not hard; water does not run away quickly but stays among soil particles and is long available to plants. There is no stagnant water, soil is airy enough. Drought occurs rarely on such positions. Plants are given more or less permanent, moderate moisture.

Herbaceous, not woody plant. Stems and leaves may be evergreen or deciduous - thus regrowing every spring. Perennials may blossom consecutively for several years. Some perennials develop special underground organs - bulbs, corms or rootstocks and these species are treated separetelly, not with geophyte and tuberous plants.