I've got some pepper seedlings that will need to be potted up soon. Two questions:
1. At what point will they be ready to be transplanted? Some have started their first true leaves.
2. Is there an organic slow-release fertilizer that can be added to the potting mix? I'm using my own mix which is 50/50 compost/coir, so I don't know if it's even necessary.
Don't rust to put your pepper plants outside. Try to hold off until 'Mothers Day', i.e., the second week of May. If you want to prepare your planting site now, you could cover the row(s) with black plastic in order to suppress weeds and to warm up the soil.
There is no real need to fertilize your seedlings until you transplant them. There are slow-release fertilizers that can be used, but most of our garden vegetables are annual plants and you want more to have more control over the plants' use of fertilizer. For example, you want to encourage fairly rapid growth and development of the plant as it establishes itself in the garden so you apply fertilizer when you transplant, and then you want to provide supplemental nutrients when the flowers and fruit begin to develop. You have no control over the rate of release of the nutrients when using slow-release fertilizers. You will enjoy better results if you use quick release fertilizers and apply them at the necessary times.