Hot weather. Hot topic. Dahlias can be grown in hot weather.
If I read, “Dahlias do not like hot weather” again on a gardening site, I might shout. Just consider this a muffled shout.
Normally numbers don’t interest me but we need some baseline numbers here to determine exactly what is considered “hot weather,” when writers use that term. Is it a normal Summer? (What is normal anymore?) Eighty degrees, ninety degrees, one hundred degrees? One hundred five degrees is hot, and considered hot weather. Dahlias can be grown in one hundred five Fahrenheit temperatures.
John and Anne Menzel of Winkie Dahlias in Australia have grown Dahlias successfully for four decades in rather harsh-hot conditions. He was cutting and showing Dahlias at 104 Fahrenheit a few years back. His Dahlia colors were vibrant and not faded, taking the show. John has even stated, “We grow dahlias in the harshest conditions.”
It comes back down to the very basics of soil, nutrients and moisture. Also consider the proper depth dahlia tubers should be planted.
Granted we pot up single tubers in early Spring with the tips and eyes poking out of the potting mix for a reason, so they won’t rot. After the tuber sprouts and gets some tall growth it needs to be planted at a depth of 4-8 inches in the ground especially if you have the higher temperatures of ninety five to one hundred five Fahrenheit. Keep those feeder roots safe and covered so they won’t cook near the surface. Your precious dahlia will also make more tubers during the Summer planted deeper, another bonus.
If clay soil is the hand you’ve been dealt, amend it with organic compost. Amend. Amend. Amend. Don’t fold. Clay soil is usually rich in nutrients, it just needs some help in breaking down and sharing them. About the only thing I know that likes clay soil is my boots. I mention clay soil because “heavy soil” is usually the reason a new gardener does not plant dahlias deep.
Shade cloth can be helpful, John Menzel uses it, at temperatures of one hundred and over. Shade cloth comes in various densities so pick one around thirty to fifty percent shade. Any higher and the dahlias won’t get enough sunlight.
Dahlias also like consistent moisture especially in hot weather. If the soil is loam it is much easier to keep consistently moist either with drip lines or overhead sprinklers, than heavy soil. Heavy soil is either too saturated or too dry. Consistently saturated or consistently dry. Similar to hardpan.
The three-way partnership works wonders between amended soil, nutrients and moisture when they are aligned to work together for healthy dahlia plants. The nutrients are easier to absorb with the correct moisture. With loam soil the roots can grow easier to get the nutrients. They all play off each other.
If your Dahlia is wilting in the heat, ask yourself: Could the plant be too wet or too dry? Too much chemical fertilizer or even chicken manure can be a death blow. Just don’t blame it on the heat please.
Until tomorrow…Enjoy the flowers.