Soil fertilizer question...should I add blooming fert?

[grotebag]

Prolly a silly question, but here goes, do I need to add anything?
This year I decided to grow in fabric pots instead of in ground in the greenhouse/hothouse.
The soil was prepared with 20% sawdust/wood chips, 15% chicken manure and the balance a light clay soil everything seems to love.
The only fertilizer added was a 1-1-1 organic slurry, the same stuff the rest of the garden gets, but only twice a month.
Plants look great(to me) as they slip into flowering yet I have no idea if they want/need more.
Bought the 'Tiger Bloom'(?) stuff that I see recommended, but afraid of burning if there is already enough in the soil to keep the plants happy.
Is there a way to tell if adding more fertilizer is an asset or liability?
Thanks in advance...

 

[pilto]

Plants look great. The only thing I would change is maybe stick some supports in there to hold up the giant flowers you are about to have on those beauties! I have that same fan. We are fan bros.