- Bark: Bark is added to improve drainage and air space within the mix. This means it will also decrease the water retention slightly. Bark mixes are better for use with mature plants that need to dry between waterings than for starting seeds.
- Coir: Coir is a coconut fiber by-product and works similar to peat in providing good drainage while also retaining water. It’s often used as a substitute in areas where peat is hard to come by.
- Perlite: Perlite is that stuff that looks like pebbly Styrofoam. It’s a volcanic mineral, although it does not affect the nutrient quality or the pH of the mix. It does add in drainage and in air and water retention, that magical balance. In fact, it is sometimes used in outdoor gardens to prevent sandy soil from leaching nutrients.
- Vermiculite: Vermiculite is those silvery-gray flecks you see in potting soil. It’s a mica-type material that is heated up and expanded, to increase its water holding capacity. The particles soak up water and nutrients and hold them in the mix until the plants are ready to access them. Perlite is also good as a soil covering for seeds that need to remain consistently moist to germinate. *** You may see vermiculite for sale at home improvement stores, for use in insulation or plaster. This grade vermiculite is not really suitable for potting mixes since it does not absorb water easily.
Staggered Plantings Ensures a Long Season
I like to space out my plantings because this allows me to have a longer growing and harvest season. Since I live in Georgia, we typically have a much longer growing season than many in the northern states but this doesn’t mean you can’t stagger your plants too. A good rule of thumb is to plant the same crop every 2-4 weeks or when your first batch of plants have put on their first true leaves.
I also like to grow different types of plants together, also known as companion planting, in order to help with pest control or to help loosen the soil for later harvest vegetables such as carrots. I like to sow radishes and carrots together in the same row because the radishes grow much faster than the carrots and as I harvest the radishes, the space they leave loosens the soil around the carrots which allows oxygen and water to get down to the carrots. I plan on growing some leeks this year so I will also plant some carrots next to them because I have read that leeks or spring onions help deter the carrot fly. This is something that I will watch closely since I have had problems with carrot flies in the past.