Sow in the spring or autumn at around 3g/m2 for 100% pure wildflower seed mixtures and 5g/m2 for 80/20 meadow grass and wildflower mixes. Good ground preparation is essential.
Wildflowers will not survive or compete in areas of lush grass or weed growth such as thistle, bindweed and nettle. It may be that you need to spend a season clearing the ground of all weeds before attempting to sow. Don’t sow perennial wildflowers into problem areas or in heavy shade such as below conifers, it won’t work. If we could give you only one piece of advice it would be to hold back sowing your wildflower seeds, this will give weed seedlings time to emerge from freshly rotovated or dug over soil. Weed seed can be buried in the soil and will germinate when it is brought to the surface. Once you have sown perennials, it is very difficult to then deal with an emerging weed problem.
Take care not to bury the wildflower seed; it needs light, warmth and water to grow. It can be quite difficult to spread 3g (little more than a pinch) of seed over a square metre. You can mix the seed with a light coloured carrier to aid in spreading the seed evenly. Sand and bran (usually purchased from pet shops) make good carriers.
When you have cleared your area of all weeds and the soil is nice and crumbly, spread the seed at the recommended rate, and in the early stages, keep well watered. Some species may need frost to help to break dormancy, so be patient - the seeds will lie in the soil until the conditions are right for germination to occur.
Unless sowing with a companion annual mix, do not expect to see flowers in the first year - perennials need to grow for at least 2 years before the plants are mature enough to flower.
Year 1 maintenance- just keep an eye on it and spot treat or remove any obnoxious weeds and rough grasses that find their way into the area. Make sure the seedlings are getting sufficient light.
Year 2 and onwards- as for year 1, allow the seeds to ripen and fall into the soil, usually towards the end of August. Cut back hard. Remove the cuttings, as they could stop the light reaching seeds that have just fallen.