May is one of the busiest times in the “Dahlia Growing Calendar.” Almost every growing zone is planting and all the questions come flooding in! I get a lot of similar ones so I figure if one person has the question, then most likely others do too. The following are either actual questions I’ve gotten over the last month or combinations of similar questions.

Q. I’m planting my dahlias, should I add bonemeal to the hole when planting? What kind of fertilizer should I use?
A. First off, what does your soil test tell you? The reason this question is so commonly asked is because people skip the soil test. It’s vital to anything you grow!! If you’ve never taken one, click here. It’s very easy! You can mail your sample to your local extension service lab or take it in person. It’s worth it— I promise.
So to answer the question above— Do you add bonemeal? Bonemeal is a good source of calcium and phosphorus so if your soil test results tell you that you need this, then yes- it’s a great way to add it to your soil. But don’t go adding it because you heard somewhere it was a good thing to do— fertilizers are expensive so don’t waste money. Also you may throw your soil nutrients into excess levels which can be just as problematic as not having enough of a nutrient.
As for fertilization after planting, I’ve got a whole blog post about it here.

Q. I pre-sprouted my dahlias using the plastic baggy method, what do I do now?
A. So I have never used this method because it’s not conducive to growing 1000’s but I did a bit of research so here goes: If you have a plant in a plastic bag, it’s basically a mini greenhouse. So keep this in mind when moving them outside to harden them off. You’ll need to move them gradually from a shady place to a warmer spot with more sun over a period of several days. Get them planted out before the sprouts get too tall- preferably not over an inch or so. If you are curious about other methods of waking up tubers, take a read here.

Q. When you start and stop fertilizing dahlias?
A. I begin fertilizing as soon as they are up a few inches. We begin our spray maintenance program and this includes fertilizer, fungicide and organic pesticides. They young plants are super vulnerable to pests at this stage so we try to stay on top of it.
I stop fertilizing about 3-4 weeks before I’m planning to dig. This may be my last frost date or it may be before. My frosts can come late here so I just plan my dig date. If we get a frost, great! If not, no big deal. You don’t want a whole lot of new growth for the tubers to support in those last few weeks. It usually around early October when we stop fertilizing. We do however continue the pest and fungus control. 3-4 weeks also works even if you plan to leave them in the ground. Just back that date up from your average last frost date. It’ll be okay if you are off by a week or two.

Q. What makes a dahlia formal or informal?
A. I’m not quite sure who came up with the dahlia forms originally. But if you are curious as to what they are and would like to see them explained well- the American Dahlia Society has a great explanation here.