The numbers on fertilizer apply to stimulating leaves (6), flowers (18), roots (6), in that order. If your tomatoes, eggplant, zucchini and cucumbers are flowering, I'd leave well enough alone for now, and give them a light side dressing of a balanced granular fertilizer or composted manure when the fruit sets. The celery would benefit from a high-nitrogen fertilizer if it is actively growing.
I envy you your rain--send some to Texas!

It was a cool, wet, and overcast spring here in Madison, Wisconsin, as well. Our garden was affected. The blueberry crop was about half of what I harvested last summer. Lettuce and beans are doing OK, but the broccoli refuses to thrive. Our tomatoes are healthy and lots of fruit, but only one ripe tomato so far. I have never used spike type fertilizer, but if it works for you, that's great. We mostly rely on compost to feed our garden soil. I don't think that fertilizer will conpensate for the poor weather we had early this season.

Spike fertilizers are really not the most effective way to fertilize your garden. That fertilizer has no way to spread throughout the soil, so only the roots that happen to grow nearby are able to access it. AND, the heavy salts in the spikes don't do the ground organisms any good either. (They are your friend. Be nice to them.) Side dress, which means add a light sprinkle of fertilizer all along your rows of vegetables about 3 inches or so away from the stalks. Marlin makes a good point, if your plants are flowering, you're probably alright the way things are. Soil, you know, usually has a certain amount of nutrients in it already, especially if you added compost, manure, or whatever to it in the spring.

Thanks for the replies.

I am new to gardening and this comment:

"The numbers on fertilizer apply to stimulating leaves (6), flowers (18), roots (6)," was very informative.

I'll let you know how it all works out at the end of the season.