How to Grow Flowers from Seed
Using seeds is a cost-effective way to grow flowers. You can start growing flower seeds indoors, in a planter, or outside in your garden or flower bed. Moisture, sunlight, and the proper soil are the most important components to growing a flower from a seed. Once the seedling becomes a flower, you should care for it like you would any other flower.
Part 1Germinating Seeds Inside
If you want to grow multiple flowers, you can purchase an indoor planter that has spaces for more than one flower. It’s important that the container has drainage holes because overly saturated soil will inhibit the seed’s growth.
If you don’t want to buy a planter, you can punch holes in the bottom of an egg carton and use that instead. Put a rag or cloth under the container to prevent leaks.
Combine the three different types of soils together in equal parts to create a well-drained soil high in organic material. Pour your flower container ¾ of the way up with this mixture.
Harder seeds should be covered with an organic material like vermiculite or sphagnum moss, while softer seeds should lay on the top of the soil. Read the seed packet that came with your seeds to determine if you should bury them under the soil or leave them on top of it.
Lightly sprinkle water on top of the soil, but don’t add too much or you could wash away smaller seeds. You can do this by sprinkling the water with your hand, or slowly pouring the water into the container from a small saucer. Either way, the soil should be moist but the seeds should still be intact.
Plastic wrap or a sealed lid will trap moisture and help the seeds germinate. Poke a couple of holes in the top of the plastic wrap so that the plant can breathe.
You can also wrap the planter in a plastic bag for a similar effect.
Germinating seeds do best in temperatures of 65–75 °F (18–24 °C). Move the planter to a warm area that gets plenty of sunlight. Alternatively, you can place the planter on an artificial heat source, like the top of a refrigerator or near the oven.
Move the planter before you use the oven or heat could damage the seeds.
If you plan on transplanting your seedlings outdoors, harden them off by leaving them outside under a shaded area for 7-10 days. This will acclimate them to the change in temperature. Some flowers have an intolerance for the cold and should be kept indoors. 
The seed package should give you a range of temperatures that the flower will thrive in. If a flower is cold-resistant, it should be labeled as hardy. Tender flowers are less resistant to cold and should always be in an area that’s over 40 °F (4 °C).
Position a small spade 2–3 inches (5.1–7.6 cm) away from the seedling. Gently dig around the seedling, making sure not to sever any of its roots. Then, pull the seedling out of the planter, with the soil around its roots, and place it in a well-drained soil in your garden.
Monitor the seedlings to make sure that they don't die after the transplant.
Part 2Planting Seeds Outside
Use a rake, tiller, or pitchfork to dig 6–8 inches (15–20 cm) under the soil. Turn the soil over until you’ve loosened all the soil in your flower bed.
You may also want to incorporate compost in the soil to promote flower growth.
The information on the seed packet will explain if the seeds have any special germination needs. Soft-shelled seeds should be pressed lightly into the soil, while hard-shelled seeds should be completely covered with soil. Read the instructions to see which method you should use.
This is useful when planting a wide variety of seeds or plants. The visual reminder will also let you know whether the flowers are growing or if your seeds failed to germinate.
Not all seeds will become flowers. Labeling will also prevent you from mistaking your seedlings for weeds.
Lightly mist your flowerbed with water so that the soil is moist. The soil should always be moist while the seeds are germinating. To see whether the soil is actually moist, press your finger down into your flowerbed. If the soil feels dry under the surface, you know you need to water your seeds.
The flowers should germinate within 3 weeks to a month. If you don’t notice that they are starting to grow, you may have to lay down more seeds.
If it rains, you shouldn't have to water your flowers. However, it's important the soil under the flowers stays moist. If you have a period of time with no rain, water them so that the top 6–8 inches (15–20 cm) remains moist.
Pruning the flowers after they have bloomed will encourage new growth. Use a set of hand pruners and clip away old or damaged flower petals or leaves.
An organic fertilizer and promote the health of your flowers and will brighten their color. Look for a fertilizer designed for your specific type of flower, and sprinkle it on the surrounding soil. Read the instructions before you use the fertilizer so that you don't over fertilize them, which could kill them.
A balanced 5-10-10 fertilizer can be used on the widest variety of flowers.