The general consensus is to never fertilize a dry plant, and it's probably good advice to follow, even though in the end it all depends on how strong the fertilizer solution is.

If the level of solutes in the fertilizer solution is greater than the level of solutes in the plant's cells. it can restrict the plant's ability to absorb water and nutrients. In extreme cases, it can actually reverse osmotic flow and 'pull' water from plant cells and cause the cell plasma to collapse and pull away from cell walls, killing the cells. We call this fertilizer burn, but the tech term is plasmolysis.

If the level of solutes in the fertilizer solution is low (fertilizing at 1/8 - 1/4 strength), and the plant is in need of fertilizing, there would be no harm in using low dosages of fertilizer solution to water with, even if the plant is dry; but if you're not confident in how things will play out, it's better to be safe and follow the adage because residual soil salts also enter into the equation.

Mother nature doesn't shut off the availability of nutrients just because her plants are blooming. There are many horticultural manipulations we can undertake to make a plant do what WE want it to do, and manipulating the timing, amount, and ratios of the nutrients we deliver is one of those things. There is, however, no good reason from the perspective of o/a plant vitality to withhold nutrients from a plant because it is in bloom.

Al

Right on Tapla!

If you let your plant get too dry you can always water it without fertilizer, wait half an hour (allows the water to "circulate" through the plant) and water it again with fertilizer added.

As far as fertilizing when in bloom, that's the time the plant is spending all it's stored energy from the previous year so fertilize away (according to directions, of course). You're even welcome to use half strength if it makes you feel better or start out weak and work your way to full strength.