Mr. Hill said:
Don't use Peat!!!! Coco coir is by far better but Rinse with a lot of clean Water before you use it. I will never use Peat again. I like as much as 1/3 Coco coir.
Peat works fine. If you notice a difference there was *some* other problem. Coco isn't cost effective here so I've used peat for decades. It's a regional thing how much it costs.
Soil often goes on sale in early to mid spring at hardware stores (keep an eye on Home Depot and Lowes weekend ads), but it depends on if you want standard (cheap) soil or a premium mix that's less likely to ever be discounted much.
As for places like Lowes, get something like the following ingredients:
1 bale peat moss (will last several seasons if you aren't growing in 250+ gallons of soil)
Scotts 0.75 cu ft top soil
Hapi-Gro 40lb peat humus
Infinity 40lb organic compost (w/manure in it)
Pearlite - crazy expensive at hardware stores, get a couple cubic feet from a garden supply store instead.
Put the tomatoes in the ground. If indeterminate types they will unquestionably need more soil than the peppers. If determinate types then consider your pot size. 5 gal. will stunt them but not much. 10 gal would be better. Plus they have more weight up top towards the end of season so denser, more stable in-ground (soil) is better to secure a cage or stake for tomatoes.
The same goes for peppers but it depends on your fertilizer regiment if 5 gal only stunts them some or a lot, with more than 10 gal. being better if you are attentive to their needs.
20% in pots is only ~ 12 to 19 plants in pots. You don't mention if you're trying to build a raised garden too and need soil for that, or only for those in pots.
Keep in mind that if the soil on your property manages to grow grass, trees, etc, then it's reasonable to put some of it in your plant mix but if it is high in clay, not a lot meaning best to limit it to 20% or less of the total mix.
For example you could use 15% ground *dirt*, 15% peat, 30% potting soil (any type not especially high in rocks or sand which some inexpensive brands are), 10% pearlite, 15% humus, and 15% compost. If other forum members here manage to trick you into thinking regular ground dirt isn't allowed (lol) then in its place put in 5% more peat and 10% more compost.
Keep in mind that "compost" above can mean the bagged product I listed above or it could mean you gather up things like leaves and other lawn debris and compost them in a pile till spring. Eventually the soil under your pile will also be suitable for using straight with little to nothing else added, but not by itself by next spring.
That is a description for a plan that includes amending the soil before reusing it again, and adding fertilizer if the plants get very large and deplete the 5 gallon buckets (which are undersized for a good season of growth in your area). You'll need new sources of NPK, calcium and magnesium whether they be through compost, compost tea, synthetics, or other off-the-shelf (expensive) fertilizer products.
but hey maybe Winland didn't know all his options and he can now buy with confidence or use leaf mold if he knows where to get some.