|• Important – do not grow tomatoes twice in the same soil, especially in container mixes. But you can certainly reuse tomato mix for other vegetables, except potatoes.
• Pests a problem in those pots? Put the soil mix into a plastic bag, close it up, and set it on the driveway for a sunny, hot week to cook a bit without damaging the soil structure. Pour the mix out and comb through it to pull out plant parts and seeds.
• No weeds or diseases? Skip the solar oven. Pour the soil onto a tarp or into a wheelbarrow and comb through it to break up clods and pull out any remaining roots.
• Look at the cleaned soil for signs it is depleted – all the particles might be crushed into one size, which does not fit all in this case. A variety of particle sizes works best to keep the soil well-drained. If no such problems exist, mix several pots of soil together and store in a closed plastic bin.
• Wimpy, tired soils can usually be amended for reuse, but after 3 seasons or so, it’s best dumped into the compost or a flowerbed somewhere. You’ll notice a change in color as well as a textural flatness. With lots of pots like yours, consider a rotation that lets you replace some each year.
• To each 5 gallon bucket of old mix, add 1 cup of horticultural lime, 4 cups of composted manure, and 4-6 cups of ground pine bark mulch. Add enough bark to make the mix feel sturdy in your hand – it should crumble but not turn to dust or clumps when you crush a handful.
• If you use a granular vegetable garden fertilizer (5-10-5 or 5-10-10 usually) add a cup of that to the mix one month before you want to use it again. Keep the mix stored in covered plastic bins so it won’t dry out – yes, plastic garbage bags in the garage will do!