Miracle Grow????
Answers:
Pretty quick, a week or so...but don't over do it! If you are using it full strength, (1 Tablespoon per gallon) only use it once a week & make sure the plant isn't suffering from dehydration when you do water with the mixture. If you are using it daily to water plants, the mixture is much less. 1 teaspoon per gallon I beleive. If your plants are looking sickly since you started using it, you're using too much.
Other answers:
1 week
1 week
A few weeks
Usually within a few days... Often times the results are quite dramatic...
about 10 days!
1-2 weeks
2 weeks- the results are great
Personally I see results within a week - but I have never seen much result when using it on daisies. Daisies seem to be immune to it or something.
Your petunias will certainly be responding to it...they'll keep blooming until frost (if you live in an area that gets frost). If your Daisies have finished blooming, then you're probably wasting the miracle gro...they're done for the year.
I myself have never used miracle gro because your plants become addicted to it. If you stop using it, you're plants will go through withdrawls and suffer.