Tubers in a car: Keep in mind that tubers are living plants. Take a little care to keep them viable. If you picked them up on the farm or from the post office, please do not leave your tubers in a hot car! They will cook and that is not good for anything except potatoes. The same goes for mail delivery, look for them to arrive and don’t let them sit out in the extreme heat or freezing temps.

So your tubers have arrived. Now what? If it is not time to plant, you have two choices:

Long term storage: Store your dahlia tubers in the packing medium of your choice (typically peet, potting soil, vermiculite, wood shavings, etc) and store them in a cool, dark place (38-45 degrees and 85-95% humidity is ideal). 

If you are planting out soon, store them in the medium I sent them in. Keep them out of direct sunlight and extreme heat. 

You can also go ahead and place them in a moist potting medium so they can begin sprouting indoors. You can either place them in a 6" pot or a gallon ziplock baggie half opened.  If you do this, be sure the soil is moist but NOT wet. Remember rootless dahlia tubers don’t like wet feet. Place them in a 70 degree area of your home with no direct sunlight. A benefit of “waking them up” inside is they start establishing roots immediately. These roots help them move and utilize water so they don’t rot. Less to worry about once you do plant them out. 

When do I plant my dahlia tubers? You don’t want to plant in soil that is less than 60 degrees. You also want to check the date of your last frost and not plant before it. A good rule of thumb is when it’s safe to plant tomatoes, it’s safe to plant your tubers. After May 1 you should be good to go in Missouri. 

Let’s talk about soil. Here in Missouri, most of us have clay soil. Tubers do not like sitting in cold wet clay soil. They will rot because they can’t utilize that water. This is another good reason to wait until it dries out and warms up a bit. If you have sandy loamy soil your soil drains better so you can probably plant a little earlier with less concern about rot. Watch your weather forecast for rain and plant when you have a good dry stretch.

Let’s plant! Prior to planting, I add a good compost to my dahlia beds every year. Once the conditions are right, you will want to dig a hole 6 inches deep and throw in some slow release fertilizer. Then mark your tuber location with a 4'-5' stake. You can tie your dahlia plant up to this stake as it grows for support. Next lay the tuber in the hole on its side with the sprout facing up then cover with 6 inches of dirt. I like to mound mine just a bit (like potatoes) to allow the excess water to run off. Don't forget to mark your tuber with a plant stake noting its name.

Do they need support? If you have a variety taller than 3.5 feet you need to give them some support. An easy way is to support them is like you would a tomato, a post or a cage. The really tall ones will need a 4 to 5 ft post. I recommend driving these support posts prior to planting because, later, as it produces more tubers, it’s easier to hit one accidentally. 

How close should I plant them? If you are planting in rows, standard spacing is 12-18 inches. If a double row, stagger the spacing in a zigzag pattern. 

Can I plant them in a pot? Yes! Because dahlias need room for their tuber clump to form, the smallest pot I recommend is 5 gallons. 14" across the top is good. Also consider that pots dry out faster than the ground. Dahlias in pots will need to be watered more often. Adding a tray under the pot to hold water will help with this as the dahlia can wick it up as needed.

How much water do they need? Other than making sure your soil is moist at planting, do not water your tubers until they have sprouted and broken soil. If you go a long time without rain and the soil dries out, water just enough to make it moist again. Once they break soil you may slowly start watering that plant. Dahlias as thirsty girls in general. Water a 2-3 times a week if no rain. 

What about fertilizer? In addition to loving water, dahlias are heavy feeders. If you didn’t throw in some slow release fertilizer at planting, no worries. You can fertilize every few weeks with fish emulsion or any other quality balanced fertilizer through the end of July. At that point I switch over to a low nitrogen fertilizer fertilizer that will focus on bloom and tuber growth rather than encouraging leafy green development. 

Let's get the most blooms! When your plants are about 10-12 inches tall, using snips or your fingers, pinch the main stem leaving 3-4 sets of leaf nodes on the stem. This will encourage branching and it will send up multiple shoots instead of one main “tree trunk” stem. This means MORE BLOOMS!

Enjoy those blooms! Here is one of the beautiful things about dahlias…the more you cut the blooms and enjoy them in a vase, the more it will bloom for you! If you stop cutting the blooms and let them die on the plant, it will signal to the plant that it needs to go into survival mode and start producing seed, thus reducing the length of bloom time. SO CUT AWAY!

How do you make sure you get long stems? Cut deep (the stem should be the length from your elbow to your finger tips for arrangements) and your dahlia will start sending up longer stems for you to enjoy! Yes you might sacrifice a few buds in the beginning, but it will pay off for the majority of the season with lovely stem length! If you stop cutting the blooms and let them die on the plant, it will signal to the plant that it needs to go into survival mode and start producing seed, thus reducing the length of bloom time. 

Dahlia blooms do best when cut in the cool of the day. So spend some time in the dahlias in the early morning or evening. These are truly some of the most beautiful flowers you can grow. 

Last but not least, in the fall you will need to dig and store your tubers if you are in zone 6 and lower or they will freeze. You can replant those tubers next season and share them with friends. Alternatively some people choose to leave them in the ground and just buy new tuber stock each spring.

Thank you again for choosing to shop with me. If you have any questions, feel free to reach out to me at hello@ruthiemaeblooms.com.  ENJOY and HAPPY GROWING!