any other options? if you have no other option -- then I guess you have to. but -- i wouldn't recommend putting a plan in Miracle Grow -- no matter how old it is.
one word: Nutrients During the veg stage - you want to be providing more Nitrogen than phosphorous or potassium During the flower stage - you'll want to provide more phosphorous, and potassium than nitrogen (not that nitrogen isn't needed) We (as growers) are able to control the amounts of these essential nutrients by adding vegging, or flowering nutrients to our plants in the proper stages. Miracle grow soil has nutrients (often with time release) which takes away your ability to provide the proper nutrient balance at the proper time. Alot of the MG soils say "food for up to 3 months" well -- 3 months is enough time to do 30 days of veg, and 60 days of flowering and be into harvest. MG soils sort of take the ability for us (as the grower) to optimize our yield through proper nutrient supplement and balances.
how much will my yield be affected if i use the MG? and would you suggest soil from the yard over this MG?
I have no idea how the MG will affect your yield -- could be very minimal... I would use MG over soil from the yard. Soil that come sin bags often have bugs in it which can be life threatening to our plants -- so I could never bring something from outside (where I KNOW there are bugs) into the house and put a plant in it. but that's just me.
I'd do a standard flush (run 3x the amount of water as the total capacity of the bucket/pot) -- maybe 2 or 3 times?
i grow in MG organic and i really like it. I have tried other MG soil and it all sucks. dont ever use a time release soil growing weed. It will cause toxic salt build up if it doesnt burn the shit out of them. i stand by MG organic, but wont recommend any other MG soil. I always mix 20% perlite in my soil. ive seen.... MG flower and vegetable MG potting soil MG moisture control personally burn plants. doesnt happen with the MG organic choice though.
i do. out of about 10 plants i see maybe one sign of slight burn, the burn stops as soon as i put them in gallon containers and the roots get a chance to spread out. IMO, this will happen with almost any soil that has nutes. I've seen some bad seedlings in FF soil. if you can get a soiless or seedling starter mix you will be much safer. make sure your PH is on and you add some perlite. you shouldnt have any problems in the MG organic choice.