Aside from the considerable economic advantage of starting seeds for annuals indoors, other advantages are the flexibility one has in choosing whatever they want to grow, and the fact that doing so will mean that when the plants are ultimately transplanted outdoors, they can be much bigger, healthier and more vigorous than anything available for purchase from a retailer.
TIMING
One of the most important things to consider when planting any type of seed indoors is when it will be transplanted outdoors. By planting the seeds far enough in advance, one can rest assured that the plants they transplant won't suffer from transplant shock. Then of course, there is the best advantage of all: the ability to see blooming flowers much earlier than they could have without planting seeds.
The general rule of thumb is that seeds started indoors should be planted a minimum of 8 weeks before they are to be transplanted outside. Before actually planting them outdoors, however, they should be kept outside during the day for a week, for hardening off. Once the transplants are hardened off, they will be more acclimated to the outdoors.
NECESSARY SUPPLIES
Containers
Peat pellets are an excellent choice. The pellets must be soaked in water for a minimum of 30 minutes. As they soak, they absorb the water which forces them to expand, so by the time they are done soaking, they will be more than double the original size. Each pellet contains a planting medium that is held inside by some sort of protective mesh covering.
The greatest advantages to the peat pellets are their size, and the fact that the entire unit, plant and all can be planted right in the soil. Eventually, the pellet will break down, but when it does, it will have added some great organic matter to the soil.
Peat pots are another good choice, because the peat will break down, just as it did in the pellets, and add organic matter to the soil. When using peat pots, however, it is necessary to purchase dirt.
Planting packs are an okay idea, but it can be hard to get the seedlings out of the packs, and that will cause stress for the plants, and then there is no guarantee that the planting packs can be used again in subsequent years.
Soil
The problem with most commercial potting soils is that they don't contain any amendments to help with aeration or drainage. Using a regular potting soil is okay as long as one can add a significant amount of perlite to the soil to improve the quality of drainage an allow air to move throughout the soil. This will also ensure that when plants are watered, every part of the soil will get evenly moist.
PLANTING
It isn't necessary to plant the seeds deeply. Sprinkle them on the top of the soil and then cover them with another very thin layer of soil. To keep better track of how successfully the seeds germinate, just plant a few seeds per container. Make sure that each container is properly labeled.
WATERING
Watering the containers after planting the seedlings will push the seeds too far down into the container. The best way to prevent this is by watering the soil before planting the seeds. It won't matter whether the seeds are watered before they are planted. There will still be sufficient moisture for them to germinate.
LIGHT
When trying to get seeds to germinate, it is important to provide adequate light. A shop light fixture that holds two fluorescent tubes will work well. By using one cool light and one warm light, it will be possible to provide the seeds with the closest thing to full spectrum light one can get. When seeds are germinating, they should get between 12 and 16 hours of light daily.
WARMTH
Seeds need warmth to germinate. There are many ways through which to provide this heat. One can use everything from the top of a refrigerator to the top of a steam register or radiator. It is also possible to purchase heat mats that are made for the purpose of germinating seeds. They vary in price depending on the size.
The easiest and most cost effective way through which to provide sufficient heat is to use the light. When the light is placed a mere couple of inches above the seed starting pots, the soil will benefit from this warmth.
The three things that are most necessary for successful germination are light, warmth and moisture. As long as all of these elements are provided and can be provided consistently, it should take anywhere from 3 days to a week for the seeds to germinate.