Seeds of hardy annuals may be planted in the open ground where it’s to flower; it is that simple. The main requirements are a fully sunny position and well-drained soil. Obviously, the condition of the soil will be reflected in the quality of the flowers produced and to get the best results the ground should be well cultivated in advance of sowing. Where the soil is poor, work in bonemeal to a depth of 2 or 3 in. and at the rate of about 2 oz. to the square yard. This is a fairly slow-acting fertilizer that will provide nourishment as the roots get down to it. Fresh manure is not a good thing for annuals as it encourages much soft leaf growth and not flowers.
Before sowing firm and rake the soil level, removing large stones and hard lumps of earth. Most flower seed is small and do need a reasonably fine surface soil to germinate. To plant the seed, broadcast the seeds by hand or plant them in rows but be sure to have just a light dusting of soil on the seed for germination. This will reduce the wasteful job of thinning. Pelleted seeds make small seeds much easier to handle and thin sowing is easily achieved. This means that the seedlings will have sufficient space to grow without the check caused by thinning or transplanting.
Do not attempt to sow seed when the soil is wet and sticky, be patient and wait until it dries out. Seed sowing is controlled by the weather not by the calendar. After the seed has been sown cover it lightly with soil and water with a fine spray. Water it just sufficiently to make the surface soil moist.
To prevent the beds from becoming dried out they may be covered with lath screens or burlap which should be kept in place until germination takes place. Evergreen branches may also be used. In dry weather, drills may be taken out and watered several times before the seeds are sown and covered with soil.
Where thinning of seedlings is necessary this should be done when they are about 2 to 3 in. high and a final thinning should leave sufficient space for the plants to develop. After each thinning water the seedlings to settle the soil around the plants. The seedlings that have been removed may be planted elsewhere in the garden, but this is not successful with all annuals. As a rough guide to thinning the distance between each plant should be about three-quarters of the plant’s ultimate height; e.g. plants that will grow 1 ft. tall should be thinned to 9 in. apart.
In the south annuals are used principally for winter display. They should be sown in August and September to flower from January.
How to Plant Annual Flowers
How to use Annual and Biennial flowers