When should I fertilize?

[mva]

Hi, I planted Marigolds and Geraniums last weekend. It's my first garden. The soil isn't the best quality and I would like to fertilize asap to ensure good growth and bloom. I planted them last weekend. When should I fertilize and what product should I use?

I also planted Blue Bird Hydrangea, Boxwood, a Nest Spruce, a Standard Blue Spruce and a Japanese Garden Juniper. Yes I did a lot last weekend . I'd also like to fertilize them but I'm not sure when or what to use.

I've tried doing the research but I haven't found anything that tells me when to fertilize.

I live in zone 5a and the plants are all in partial sun.

Thanks in advance for your help.
M

[Eeyore]

You can fertilize any time now. A good all purpose fertilizer should be fine.

I'm going to move this post to Plant Talk. You'll get more replies there.

[Sheikea]

I have already fertilized here.I use Miricle Grow for my babies and I use it once a month.I am sure I could prob do it more often though..