I cannot tell you how clueless I was about Petunias until recently. But after some egging on from a friend, I decided to see if I could grow some indoors in water. My friend planted the lovely AeroGrow seed kit in her AeroGarden and scarcely more than a month later she had blossoms. Wow! They were so pretty, but I did not want to wait a month. So, as it was November, I decided to see if there were any "hurt" seedlings on sale locally. I found a nice six-pack that were definitely past their prime and even the clerk wrinkled his nose when he rang them up for $1.99, saying, "Those are somewhat bedraggled."
Here is how they looked after a day in my AeroGarden Clinic:
Here is a detail of the leftmost and rightmost plants both before and after a 5 day stay in the AeroGarden Deluxe:
The first night in the hydroponic system I used plain filtered water and left the lamps off. After a few days, I fed them General Hydroponics Flora series nutrients as follows:
1 ml Grow
3 ml Micro
6 ml Bloom
I did not premix the nutrients, but instead, using small plastic syringes from the pharmacy, simply injected each concentration separately from its own syringe into a different part of the reservoir. The AeroGarden reservoir holds a little over 3L of solution, and I normally use a ratio of 1:2:3 (grow:micro:bloom) for flowering and fruiting plants, but this time I just let intuition guide me, and for the short term at least, it seems to be working.
I have blogged about petunias here and here here, too.
Here is a before and after, one day and then one week after removing these plants from their dirt:
Since Christmas this garden has been averaging about 20 blossoms on any given day, and we got enough new plants to populate an AeroGarden 3 as well: