In choosing a container for your seedlings, consider not only convenience but also how much damage might occur to seedling roots at transplant time. If roots are torn or broken during transplanting, otherwise healthy seedlings may stop growing while they recover from their injuries. To make transplanting less of a shock to plants, choose individual containers for seed starting. Seedlings can be started in everything from styrofoam coffee cups (which are free from the office waste basket) to peat pots purchased from the local garden center. While we would never discourage personal creativity and ingenuity, our advice if you are a beginner in this seed starting business, go with the commercial products. You can choose from individual containers to seed starting systems that have space for 15 to 40 plants.
Individual containers – If you are starting more than two dozen plants, we recommend what are called Jiffy 7’s. These are disks, made of peat moss, about the size of a fifty cent piece but a little thicker. When you place them in water, they expand into a uniform seed starting material a little smaller than a tennis ball. These devices can be planted directly into the ground, thereby reducing any serious root disturbance from transplanting. If you are starting only a few plants, then we prefer what are called “peat pots”. These are containers made of peat moss and come in various sizes from about 2 inches high to as big as a water glass. You fill them with a planting material and when the seedling is ready to put outside, you plant the pot and all. The peat pot breaks down and adds organic material to your soil.
If you do not use Jiffy 7’s which serve as their own containers, you will need some growing material to put inside your container. Major Rule – Never use soil from outside to start seedlings; ever. That soil has all kinds of potential disease problems for vulnerable seedlings. You are looking for what is called a "soiless mix". ”Such a material is sterile, and free from disease problems. It is also a material that drains well while simultaneously retaining moisture. You can buy soilless mixes designed especially for seed starting from any garden center. If you wish to make your own, a standard recipe is one part vermiculite, one part perlite, and two parts commercial compost or commercial potting soil.