Weed regularly to stop any undesirable weeds establishing.
Allow the wildflowers to drop their seeds after they have finished flowering. This will allow new plants to grow in the same place the following spring. If you’d rather, you could collect the seeds and use them to sow a wildflower patch somewhere else next year!
Once the seeds are ripe, around September or October, either cut or pull out the spent plants. If you have a small wildflower patch, simply shake the flowers to ensure all the seeds have fallen. In a larger flower patch, leave them on the soil for a week or so to drop all their seeds, then rake up the cuttings.
In the second year it’s best to sow more seeds, as there may not be enough already in the soil. In the following years there should be enough seeds in the soil to allow your wildflowers to re-grow naturally each year.