You should start the process of potting your Dahlias indoors around March or April. They should be potted during the spring and will eventually sprout within weeks. You should nurture them indoors and then plant them outside in May, avoiding the frost. They will then go on to flower in the summer.
Follow these simple 8 steps and your Dahlia tubers will grow fine:
1. Get Them Started Early
When you bring the tubers back from the store, be sure to start them early. Don’t leave them in the bag to collect mold. If they’re dry, soak them in a bit of water for an hour or two, and give them a little time to air out. If they’ve been kept in storage do the same. Get them started in March or April, depending on where you live.
2. Make Sure The Pot Is Large Enough
Dahlia roots can sometimes be quite large and stick out awkwardly so measure up the roots by placing it inside the empty pot or tray. The Dahlia tuber should easily fit in without squashing the roots up. The more space it has to grow, the better. Make sure the pot is deep enough and has holes at the bottom for drainage.
3. Layer The Bottom Of The Pot With Potting Soil
Using potting soil, layer the bottom of the pot and form a nice little mound in the middle. The mound is so the bulb can rest on top of it with the roots placed around the sides.
4. Place The Dahlia Tuber Into The Pot
Place the tuber on top of the soil, roots first in the middle of the pot, making sure the top of the bulb is pointing upwards. The tuber may or may not have a green sprout sticking out of the top of the bulb. If it doesn’t, you will see where the top of the dahlia is by a cut in the stem.
If you are growing more than 1 in a larger pot or tray, don’t pack them up close to each other. It is best practice to place them side by side, with a little space in between.
5. Fill The Pot Up With The Potting Soil
As you fill the pot up, shake the pot to avoid any air pockets, pack around the bulb and make sure the top of the stem is poking out of the soil. You should be able to see the stem and growing buds slightly out of the soil, placed slightly below the rim line of the pot.
6. Water The Soil
Give the soil a good first watering and make sure the soil is always moist. But don’t over water and make it soaking wet, just keep the soil moist.
7. Label The Pot
Write “Dahlia” and “the date potted” onto a label so you can keep track of your work and move on to your next project.
8. Make Sure They Get Plenty Of Sun Rays
Leave them in a greenhouse, or a sunny part of the house (near a window) and take them outside on warmer days. They will start to shoot within weeks in the spring and then flower throughout the summer.
How Often Do You Water Dahlia Bulbs?
Don’t over water Dahlias as they’re starting to grow, just keeping the soil moist is enough to encourage growth. When you see it growing after a few weeks, give it a thorough watering about twice a week. If the weather is very hot and the soil is drying out quickly, give it another watering.
When Is The Best Time To Plant Your Dahlias Outside?
Always wait until after the frosty days are over and plant them outside, around May. By this time, your Dahlia tuber will be sprouting nicely and within weeks they will be starting to flower (around June or July), which should last until after the summer (around October).
Do Dahlias Do Well If Left In Pots?
Dahlias grow quite tall, so if you plan to keep one in a pot, go for a smaller variety. Use a sturdy pot so it doesn’t fall over after a bit of wind, and give it support if it starts to grow tall. Make sure they are in a pot that has holes in the bottom to allow for drainage.
Depending on when you start or where you live, starting Dahlias in pots has about a 6 to 8 week turnaround time until they need to be planted outside. Start them off at a date with the intention to plant them outside after the spring frost.
Take them out of storage, give them a soak, make sure you use a pot big enough, put soil at the bottom of the pot, place the tuber on top of the soil, fill up the pot with soil allowing the top of the stem to stick out, water the soil, label the pot and give it plenty of sun.
Within weeks you will see it sprouting with growth, plant it in your garden after the frost has passed, and within a few more weeks your Dahlia will have flowers growing throughout the rest of the summer.