Dahlias (DAL-ee-a) are one of the most successful plants in the world, but not because of anything they’ve done in nature.
Instead, these Central American natives have become so popular that in less than 500 years, they’ve gone from a genus of 42 species to a global phenomenon with over 57,000 registered cultivars and as many as 100 more being added annually.
Hardy and glorious as they are in the garden, you might not have known that they’re not limited to the great outdoors.
In fact, while dwarf Dahlia species are often grown in pots, you can actually grow a full-sized specimen (even the biggest ones) in containers.
This means you can enjoy their wonderful blooms in almost any climate.
How To Grow And Care For Dahlia In Pots
Growing the many types of Dahlias in a container is actually easier than growing one in the ground.
Here’s everything you need to know to grow one of these plants in a pot or container.
Choosing A Container For Your Dahlia
The first step is a simple but important one.
Dahlias can grow in almost any container, but you’ll definitely want to make sure that the container is fairly deep and has adequate drainage holes.
You’ll also have to keep in mind that these plants will get much, much bigger, so you’ll need to repot occasionally.
Choosing Soil To Grow Your Dahlia
Any good, well-draining potting soil will work, but you’ll want to amend it with perlite or coarse sand to ensure optimal drainage.
Likewise, you may wish to add an organic component such as sphagnum moss, as these plants can be heavy feeders and will drain the soil of nutrients over time.
A homemade mix of 1 to 2 parts potting mix and one part each of moss and perlite can do wonders.
Planting And Transplanting
Depending on personal preference, you may wish to add a layer of gravel to the bottom of the pot to add an extra buffer layer against overwatering.
- Fill your container ⅓ to ½ full with your potting mix, then add the bulb.
- Add more soil until the tuber is 2” to 4” inches below the surface, firming down the soil to prevent air pockets.
Some growers prefer to start the plant off first, then transplant it to a pot once it’s sprouted and has some decent roots going.
Repotting frequency has a lot to do with whether you’re dividing the tubers.
If so, you should repot every 1 to 2 years in early spring using fresh soil.
If you aren’t dividing, the plant has to be repotted every 2 years to replace the soil or when it becomes rootbound.
Watering And Feeding
The soak-and-dry method is your best friend when it comes to dahlias.
When the soil is dry 1” inch down, it’s time to water.
Use room temperature distilled water or rainwater, pouring slowly and evenly until you see seepage from the drainage holes.
Remember, it’s easier to overwater a container plant, so never rush a watering.
Every 2 to 3 weeks, you may wish to use a neem soil soak instead of plain water.
This will boost your plant’s immune system and can prevent or defend against several types of bug infestation, as well as some fungal and microbial infections.
Feeding a potted Dahlia plant is very straightforward compared to a grounded plant.
A balanced liquid fertilizer applied monthly according to the package instructions works best, although a fertilizer with half as much nitrogen (ex: 5-10-10) will also work well.
If you can stand the smell, fish fertilizers are another good option, again applied according to the package.
When you pot a plant, you’re creating a tiny environment for them to live in. This means they won’t work the same way as they do in your garden.
Regular repotting can help reduce the buildup of mineral salts, while slow watering can help reduce the risk of overwatering.
As with the garden, nitrogen has a habit of getting leeched out of the soil but will be less noticeable since the plant will likely not grow to full size anyway.
All of the same pests can still be a problem, so avoid overwatering and regularly check for signs of aphids, spider mites, snails and slugs (if outdoors), or other common pests.
Root rot is the biggest threat, but proper watering will reduce the risk of this and other moisture-related infections.
You may also find you need to work a little harder to get those perfect blooms in the same volume as with an outdoor plant, but that work means you can enjoy the flowers both indoors and out.