Fertilizing Your Dahlia Plants

Do you dahlia plants need fertilizer?

A gorgeous “gay princess” dahlia flower.

If your soil has been amended in the fall and spring with organic matter, chances are that you don’t need much, if any fertilizer for your dahlia plants. And, if you aren’t sure, I highly recommend a soil test. You can read more about soil testing here.

In the early season (April-June, depending on your growing zone), dahlias thrive with a fertilizer focused on developing leafy growth. Look for a nitrogen rich fertilizer. I like this fertilizer because it’s organic, but any fertilizer with a large first number, ex 5-1-1, will work.

In mid-season, when your plant starts putting out its first buds and has a good amount of leafy growth on it, you can switch to a fertilizer to promote more blooms. I like this fertilizer, because it’s organic. You can re-apply this at 3-4 week intervals until Mid-August. Any “all purpose” fertilizer that is lower in nitrogen and higher in potassium and phosphorus (the “p” and “k” numbers of the N-P-K fertilizer formula) will work.

I don’t advise applying fertilizer late in the season (mid/late august or thereafter).