On the dahlia train we are pulling into the bloom station. Look at the beautiful colors and shapes. Once called “garish”, dahlias are now appreciated for their bright colors. Our culture has become bolder, and so has our flower.
There are a lot of opinions about mid-summer fertilizers, and as usual, there is no agreement. I applied a time-release fertilizer before I planted, and that should carry through the season. Others prefer a shot of nitrogen or a foliar spray during the gaps in mid-summer’s scorching weather. Most agree that only potash should be used after mid-August to encourage tuber development
More importantly, the plants need water to continue vigorous growth. The best practice, if there is one, suggests one inch of water a week. To be honest I have no idea what an inch is from a drip line or sprinkler. I do know that it takes a lot of rain to reach an inch on my rain gauge. For several years I planted a Pyrex cup in the dahlia bed to estimate rainfall and what I was applying. It was a rough measure, but seldom reached an inch a week during August. There are those who believe that hand watering is insufficient. Do what makes sense to you.
If your goal is to have garden dahlias with stems, it is important to remove the side shoots on the stalks you will use for cutting. I typically remove four pairs of side shoots on the dahlias with large blooms and three or four on the smaller ones. What size vase do you plan to use? That will give you a good hint. I like 12-inch vases and to have the bloom rise from the vase about one-half the height of the vase. Many others like the short arrangements currently in vogue so they adjust the stem length accordingly. Classic design says the stems above the vase should be one and one-half the height of the vase. Do what pleases your eye. You can't go wrong with dahlias!
Remember, if you prefer straight stems you should apply a second or third tie. If the bottom one has become tight, remove it, AFTER you put one higher on the plant.
Ventilation (airflow) is important to avoid mildew and other problems. That is why we space the plants as we do. It is also recommended that you remove the bottom two or three pairs of leaves to create air space. At this point, they are not contributing much to the growth of the plant, because there is little light down there. If this is too much work, forget it.
If your foliage has begun to look funky, take it to the next dahlia meeting or a good garden center for a diagnosis.
