when to fertilize?

[hopheaddy420]

I have 2 centennial and 2 cascades. I started them about 2 weeks ago, and all 4 have broken the surface. Just wondering about fertilizer, when and if even needed, and what kind to use.

 

[Suthrncomfrt1884]

I prefer to keep the fertilizer off of the plants. So, I usually wait until they're long enough to start training, then I'll fertilize the ground around them.