The Dahlia is a flower that just exudes romance with every petal. Their intricate designs and vivid colors have been enchanting gardeners and flower enthusiasts for centuries, and they continue to hold a special place in the hearts of those who appreciate the beauty of nature.
Dahlias are consistently one of the most popular and sought-after flowers around the world, and their beauty and versatility have made them a staple in floral design. These flowers can be found in a vast array of colors, shapes, and sizes, making them a go-to choice for designers and gardeners alike.
The purpose of the following guide is to offer some context on the process of planting and growing dahlias in Texas as well as to discuss some of the challenges associated with these plants and how to overcome them to produce a healthy crop to enjoy year after year.
My first few years of growing dahlias on my farm has taught me some tough lessons about tending to these amazing plants. I hope that some of my trials and experiences can give others the tools to succeed in cultivating these gorgeous blooms. Despite the challenges, the dahlia continues to be one of my favorite flowers to grow every year and truly represents, to me, what it looks like to be a flower farmer.
Selecting the Best Type of Dahlias to Plant in Texas
Texas is NOT an easy place to grow Dahlias. A quick search on Wikipedia for Dahlia will reveal that these are plants native to Mexico and Central America, leading one to presume that these are heat loving plants.
While it is true that these plants have their origins in traditionally warmer climates, Dahlias are not very well-suited for extremely hot conditions. They generally prefer cooler temperatures and can struggle to photosynthesize and produce energy when it gets too hot.
When temperatures rise above 85-90°F (29-32°C), dahlias can experience heat stress, which can lead to a range of problems, including reduced growth, wilting, and flower drop. Additionally, high heat and humidity can create favorable conditions for pests and diseases that can also harm dahlias. This is why it is vital to properly select your dahlia varieties to meet the climatic demands of your region prior to purchasing your tubers. I have lost more dahlias than I care to admit because I chose the wrong varieties for my North Texas climate.
My first season, I selected my dahlia varieties from a website based solely on color and aesthetic. Being a complete novice, I did not think about the properties of each dahlia variety. As a general rule, I have found success with growing dahlias that have leaf profiles that are on the smaller scale.
Single-flowered dahlias, Anemone-flowered dahlias, Collarette dahlias, and some of the Decorative dahlias, including the 'Bishop of Llandaff' and 'David Howard' varieties, tend to be more heat tolerant compared to other dahlia types. These varieties have less dense and intricate petals, which allows them to tolerate high temperatures and maintain their form and color in hot weather.
In contrast, Dahlias with fully double flowers, such as Waterlily dahlias, Pompon dahlias, and Peony-flowered dahlias, can struggle in very hot conditions. These varieties have dense, layered petals that can make it difficult for them to photosynthesize and produce enough energy to sustain the plant during the hottest periods of the summer. This is not to say that growing these types of dahlias in Texas is impossible. With the proper watering and shade covering during the intensely hot hours, these dahlias can do just as well as any other type of dahlia.
Here are five types of dahlia that I recommend starting in any Texas garden:
- 'Bishop of Llandaff': This dahlia variety has dark red flowers and black foliage that looks beautiful in landscapes. A similar variety but with coral flowers is "Mystic Spirit".
- 'Karma Choc': This dahlia has deep burgundy, almost black flowers and make for a great addition to the garden.
- "Thomas Edison" : This is a purple dinnerplate dahlia that we've grown with much success, they make great cut flowers.
- "Cornel" varieties: This type of dahlia comes in multiple different colors and seems to handle the heat here much better than a lot of the dinnerplate varieties. Also a great cut flower.
- "Peaches N Cream": This dahlia variety is quite large and makes for the perfect cut flower.
Planting your Dahlias:
Choosing a date:
Dahlias are typically planted in the spring, after the danger of frost has passed. In Texas, this usually means planting in late March or early April. I have found that it is useful to utilize the Farmer’s Almanac in conjunction with tracking local weather forecasts to determine the best 1-2 week period in which to plant out.
If a significant freeze is expected, I have found it wise to practice patience and give the weather a chance to warm up before initial plant-out. Remember, this stage is when all plants are at their most vulnerable. We want to give them the best chance to succeed which sometimes means holding off and going with the flow of nature.
Pre-sprouting dahlia tubers is helpful for success in growing dahlias in Texas. By allowing the tubers to begin growing shoots indoors a few weeks before planting outdoors, they can establish stronger root systems and be more resistant to pests and diseases as well as give you the possibility for an extra (early summer) blooming period. Additionally, pre-sprouting can also help gardeners to identify any potential issues with their tubers before planting, such as rot or damage, which can be addressed before planting to increase the chances of a successful growing season.
Note: It is important to realize that, while pre-sprouting has terrific benefits for the plant, this process will expose an extremely temperature sensitive portion of the plant directly to the elements. It is crucial to take heed to the previous instruction of choosing your plant-out date wisely if you choose to pre-sprout.
Planting Dahlias with Bone Meal as a Soil Amendment
While dahlias are considered to be plants that do well in poor soil, adding bone meal as a soil amendment can help to provide the dahlias with the nutrients they need to grow and bloom. Bone meal is a natural source of phosphorus, which is essential for root growth and the development of healthy blooms. In my experience with growing dahlias, I have noticed a distinct difference when planting with the addition of bone meal versus when I have not. Tubers that I have planted with bone meal have developed significantly more tubers, on average, by the end of the season. Each of these additional tubers can be divided to create its own individual plant for the next season.
When planting, have a bucket of dry bone meal powder at the ready. After digging the hole for the tuber, take a small handful of bone meal from the bucket and place it directly into the hole. Next, take your tuber and plant it directly onto the dry bone meal powder and cover well with soil.
This one extra step while planting will give the young tuber a nutritious boost for healthy root growth early in season when they are at their most vulnerable. Dont worry too much about an exact amount per handful. Nature will use what it needs and find a way to use the rest.
The Proper Planting Procedure for Dahlias
Dahlia spacing is a vital element for the success of the plant throughout the long season. The depth of tuber planting does not vary much depending on variety. Each tuber should be planted at a depth of 4-6 inches. This will help to protect the tubers from any harsh temperature fluctuations in early spring and will also ensure that they have enough soil surrounding them to hold moisture and develop a strong initial root system.
The more important factor is how much spacing there is in between each tuber. The horizontal spacing is usually determined based on the estimated size of the mature plant at full growth. Like with any other plant, the larger the variety, the more space there should be in between each plant. As a general rule, most dahlias are planted with 18-24 inches of horizontal spacing, but to ensure complete accuracy, it is highly recommended to research the particular variety you’re planting and follow the spacing instructions provided.
The emphasis on the horizontal spacing of each variety is due to, both, the energy requirement of the plant while growing as well as the shading benefits of proper plant spacing. Planting varieties too close can cause the root systems to compete for soil nutrients early on, possibly stunting growth and production. Planting too far away can cause the hot overhead sun to dry the soil out and therefore the roots of the plant. Proper spacing will benefit the plant by allowing the growing foliage to keep a cooler and more moist soil to protect the health of the root system.
Watering Requirements for Dahlias in Texas
If it's not apparent already, dahlias are one of more high-maintenance flowers to grow. This is also true when it comes to watering requirements. In my experience, finding the correct balance in the watering schedule has been the toughest challenge I have faced. Not enough water and the delicate flowers will be at risk of heavy pest pressure or frying in the sun. Too much water and soil can over saturate causing tuber rot and ultimately complete plant failure.
These watering requirement challenges lend to why it is so important to prioritize overall soil health as well as following proper spacing instructions discussed in the above text. You should have healthy enough soil to retain moisture without becoming saturated, and you will want to reap the benefits of natural foliage shading in order to aid in having a consistent watering schedule. Bottom line, you do not want to have to be consistently over-correcting all season.
My recommendation, in conjunction with the previously mentioned tips, is to water deeply once per week during the growing season. With that being said, Texas is known for its absurdly hot and dry periods throughout the summer months. During these periods where daytime temperatures consistently reach above 100 degrees Fahrenheit, I would suggest checking the top few inches of soil for moisture level and adding additional watering periods as needed. Make sure to approach these additional watering periods with caution, as one too many can easily saturate the soil leading to dreaded tuber rot.
The Importance of Shading Dahlias from the Heat
As I have mentioned, shading from the intense summer heat is crucial for sustaining dahlias throughout an entire growing season. Here are a few options for creating some much needed reprieve from the Texas sun:
- Planting taller plants to the west of your dahlias:
Dahlias need a solid 6 hours of direct sunlight during the day to grow to their full potential. They really only need protection from the harsh mid-afternoon sun that we get in Texas. Growing a vigorous vining plant on a trellis like hyacinth bean, which is capable of growing 10 feet during one season, is an effective option for safe-guarding your dahlias
- Planting in Pots:
If you are looking to enjoy the beauty of dahlias in your home garden, but don't plan on growing rows and rows of them, a great option is to plant your dahlias in a pot that can be placed or moved into a shaded location in the yard when those hot summer days move in.
- Building a structural shade covering
If you have the perfect spot in your yard to grow dahlias but it’s fully exposed to the sun throughout the day, it is possible to build a large overhead structure to hang a commercial grade shade cloth. This is certainly the most difficult and expensive route to take, but if you are a burgeoning farmer or just want to grow large areas of dahlias, this may be the best option. In this case, I would suggest using a shade cloth with no greater than a 40% shade density. Any more than this can block out too much sun, but will definitely mitigate the effects of harsh overhead sun.
Best Practices for Harvesting
When it comes time to harvest dahlias, there are some important details to keep in mind. There is nothing more frustrating than spending months caring for a crop only to mishandle the harvesting process and losing out on the reward for all of that hard work.
1.Starting with clean equipment
You'll want to start by using clean shears for harvesting your stems to avoid bacteria from contaminating your stems. Using warm soap and water is sufficient for this step.
- Get your stems in cool water immediately
Dahlias are hollow stemmed flowers. This means they do not have an adequate store of water in the stem after they are cut. Having a bucket of clean, cool water handy during harvesting will help to avoid plant shock and gives the stem an immediate source of hydration. You can prolong the vase life by 1-2 days by processing the stems properly. They generally only have a 4-6 day vase life when handled perfectly, so taking care in this step can significantly increase the life of your dahlia stems.
- Sear the stems
Searing your stems is the next step in processing. Have a pot of boiling water ready and sear the first 1-2 inches from the cut side of your stem for a couple of seconds. This helps to eliminate any remaining bacteria on the stem and creates a fresh surface area to aid in water absorption.
- Cutting stems at a 45 degree angle underwater
Try cutting the stems of your dahlia while holding it underwater at a 45 degree angle. Doing this helps to reduce the amount of air bubbles that build up, preventing water from getting all the way up the stem. Cutting at a 45 degree angle, with a sharp knife, helps to maintain a clean, smooth cut area which prevents bacteria build up.
- Use pipe cleaners
Lastly, try using a wet pipe cleaner in the stem of the dahlia. With the dahlia being a hollow stemmed plant, a wet pipe cleaner in the stem can aid in multiple ways. For one, it can help keep a consistently hydrated environment in the stem over the life of the flower. Secondly, the pipe cleaner will work to add structure to the stem as dahlias tend to suffer from breakages with even the most careful handling.