Posted: 11/04/2015 at 01:06
You are going to have a very limited choice of things you can sow direct and I can't find any annual plants that will cope with full shade. Annuals germinate, grow, flower and set seed in one season and need sunlight to fuel it all.
However, there are shrubs, biennials and perennials that will be quite happy there and can give you a long season of interest through the year from foliage, flowers and /or stem colour.
Mahonia is a shrub with glossy, evergreen foliage and scented yellow flowers in late winter to early spring with dark purple berries later on - https://www.rhs.org.uk/Plants/98703/Oregon-grape-Charity/Details is a good form and widely available.
Angelica gigas is a tall plant that would provide height and foliage interest as well as flowers in late summer - https://www.rhs.org.uk/Plants/1275/Angelica-gigas/Details?returnurl=%2fplants%2fsearch-results%3fform-mode%3dtrue%26context%3dl%253den%2526q%253dAngelica%252bgigas%2526sl%253dplantForm%26query%3dAngelica%2bgigas%26aliaspath%3d%252fplants%252fsearch-results
Foxgloves are usually biennial so flower, set seed and die in their second year. They are easy to grow from seed and come in shades of white, apricot, cream with purple speckles and the common pinky purple form. There are also perennial forms but these can be tricky in my experience and the biennial forms set seed freely so you'll always have some new stock flowering every year if you don't hoe up all the seedlings.
Tiarellas are low growing and make good ground cover. They have pretty lobed leaves and produce frothy, creamy flowers in spring.
Hostas should do well. They come in a huge variety of leaf size and colour from green through gold, glaucous blue and variegated and they produce spikes of white or lilac flowers in summer.
Saxifrage 'London Pride' should be fine too and will produce rosettes of glossy green foliage with 30cm spikes of tiny flowers.
You can look up all of these on the RHS website or google to find cultivation details then go to your local garden centre or nursery to see what they have that fits your wish list.