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Be careful with dahlias; they are highly addictive. Proof of that can be found in my portable greenhouse in the backyard which is nearly overflowing with potted up dahlias. I suspect I’ll have about 100 in my garden when it’s all said and done.
If you haven’t grown dahlias, rest assured, they are nice in small groups as they are by the dozens, and although I spend a lot of time fussing around with them, they are not difficult to grow.
I plant them in two ways: The “extra” way and the easy way.
THE ‘EXTRA’ WAY
By my way of thinking, the “extra” way of dahlia planting has three advantages:
- You get blooms earlier, often a few weeks before you would normally.
- They are easier to space properly as you are dealing with plants, not tubers.
- They give you something to fuss over while you’re waiting for gardening season to start.
But there are disadvantages, including the added cost of potting mix and possibly plastic pots (although I reuse pots from plants e purchased), and a bit of time spent caring for them.
In this method, you pot up tubers ahead of time and get them growing before planting them in the ground. I usually start potting up tubers about a month before my last average frost date (here in zone 5 Wisconsin that translates to potting in early to mid-April based on a mid-May last frost date).
Use regular potting mix (it’s best not to use mix with fertilizer mixed in) in a gallon-size nursery pot. Very small tubers can go in smaller pots. Put a few inches of potting mix in the bottom of the pot, then lay the tuber in on its side. (If it’s too big to fit that way, you can angle it slightly.) Cover the tuber with another 3 inches of soil. Just moisten the soil and then bring the pots to a warm spot.
With a few inches of potting mix in the bottom of a pot, lay a dahlia tuber in on its side, then cover with about 3 inches of potting mix.
At this point all they need is warm to sprout, not light, so I just stack them up in big tubs in the house.
Tubers sprout at different times, so after a few days, start checking for shoots emerging from the soil. This is when they need light. If you move them outside at this point you’ll never have to worry about hardening then off, so it’s best to get them outside into the sun.
Dahlias are pretty easy to grow but they are fussy about temperature. You really don’t want the out in less than 50 degrees at this point, but often a protected spot with bright sun will be warmer so you can move them there. Bring them in at night if need be. Or you can use a popup greenhouse like I do. Whatever you do, don’t skimp on the light.
At this point you also want to start regular watering. They don’t need to be drenched, just not dry.
It’s safe to plant them in the garden (or their final container) when the soil temperature is 60 degrees. You can use this method at any time, and you may want to, especially if you want to keep a close eye on a tuber, regardless of how close you are to the safe time to plant out. However, the closer you are to the safe planting-out date, the less advantage you’ll realize as far as early blooms by using this method.
THE EASY WAY
If that all sounded like a lot, the good news is that there’s a much easier way. You can plant your tubers directly in the ground when it’s time and skip all that fussing. You’ll have to mark them so you remember where you planted them and they’ll bloom slightly later than those you started earlier, but they’ll still grow beautifully.
You want to plant them in full or at least part sun about three inches deep by laying the tuber on its side.
Dig a hole about 4 inches deep, and cover over, then water. It’s as simple as that!
Wasn’t that easy?
Regardless of how you plant, there are a few tips that will help you grow beautiful dahlias.
- Dahlias appreciate relatively rich, good-draining soil, but you don’t need to go to extremes to achieve either. I have pretty good soil that’s been amended with compost over the years, but I mix in a bit of a balanced organic fertilizer (something like Espoma Plant-Tone) before planting.
- The two rules for planting are warm soil that’s not soaking wet. A 60-degree soil temperature is good (honestly, feeling it with your hand is usually a pretty good way to judge) and you don’t want to plant if it’s been raining for days. Dahlia tubers don’t appreciated cold, wet soil.
- Stake right away. I speak from experience here. You might think you’re going to get lucky and your dahlias won’t fall over, and for awhile they will appear to defy physics, but fall they will. If you stake when you plant it will never be an issue. I use a variety of staking methods, but generally speaking, a study single stake that you can tie the growing dahlia to with soft twine, will work. For planting in a straight line, I use a Florida weave method.
- Pinch out the growing tip when there are about three or four sets of leaves (or when it just get too tall). Just pinch out the stem right above a set of leaves. This will encourage branching and you’ll get more flowers.
- Fertilize occasionally during the growing season. I use a mild organic liquid fertilizer with less nitrogen (the “N” in the NPK numbers on fertilizer) than potassium or phosphorus.
- Deadhead or cut flowers often. Cutting flowers will lead to more blooms, but if you choose to leave them on the plant to enjoy (and who wouldn’t want that beauty there), deadhead spent blooms by cutting the flower stem back to where it intersects another stem.
- When you receive tubers in the mail, they’ll probably be packed in peat moss in a bag. Open the bags and store them somewhere cool and dark, like a basement, until it’s time to plant them. They won’t look like much, but at the top of each tuber (the neck) there are little buds called eyes. Sometimes you’ll see them and sometimes they might even have sprouted a little, but even if you can’t see them, they are there and this is where the plant will sprout from.
Dahlias are sometimes a single tuber or a cluster of tubers. If they come in a cluster like these, leave them together and plant them as one.
Dahlias will sprout from eyes on the neck of the tuber. Sometimes they will be visible, like the white nodule on this tuber.
If some of that sounds familiar to you, that’s for good reason. A lot of the care that dahlias appreciated is the same as that for tomatoes. In fact, if you treat your dahlias like you treat your tomatoes, odds are you’ll be in good shape.
So how do choose dahlia varieties? Since most varieties require the same care, it comes down to your personal preferences, although the one thing you should pay close attention to is the height. Obviously, the taller the dahlia, the more extensive and important the staking needs to be.
Here are some of the varieties I’ll be growing this year, almost all of which are new to me:
VERRONE’S OBSIDIAN
I’m very excited about this unusual variety with skinny, almost black petals. Dark dahlias are such an amazing contrast in the garden and in a vase. And since it only grows to 26 to 30 inches tall this is one variety you might be able to skip staking if you plant it in a not-too-windy area.
YELLOW BIRD
This is such a happy flower and you’ll also make the pollinators in your garden happy too. Bees and butterflies go nuts for these single-type dahlias. This is another short one, making it great for the front of the garden where you can sit nearby and watch the pollinator action.
ISLANDER
This is probably what most people think of when they picture a dahlia. It’s huge, fluffy and a gorgeous shade of pink. One flower will make a bouquet.
MYRTLE’S FOLLY
This flower looks like a fire: reds, pinks, yellows and oranges with deeply cut petals that make it look like the best kind of crazy pom pons.
MELODY ALLEGRO
This pinky bicolor is full of flowers and, at 24 inches tall, perfect for use in containers. Just stunning color on this one.
ORANGE TURMOIL
This semi-cactus variety has such amazing texture and is so unusual looking. It would be amazing in a bouquet of hot-colored flowers.
Don’t let growing dahlias intimidate you: Those big, bold flowers are baked into that little potato-looking tuber you get in the mail. All you need to do is give them the right conditions, no matter which way you go about it.
Remember, you can use the code IMPATIENT20 for up to 75% off and free shipping at Breck’s.
Check with your local grocery store if they have a floral section. Or regional grocery store gets their cut flowers shipped sitting in about a 2 gallon bucket (black). And they throw them out! I get them and drill a few holes in them and they are great containers. Just the right size for a pepper or a flower. Best, they are free. I have some which are a year old and are still in good shape.
Good morning ! I have ordered 15 dahlias this year mostly because of your dahlia video from the summer. Half are in a raised bed and the others are shorter and set in the landscape. I live in Georgia so it’s actually almost time to pinch some and I’m scared ! Your videos and blogs are so helpful. Thank you so much
Hi, Melissa! It is the same with us here in Oklahoma. Dahlias are a bit tricky to get started here, so I am so thankful that once I was able to get them started, they have come back each year. Pinching them back makes me flinch when I do it hoping that I did not ruin anything, but so far so good. My issue is keeping the darn things staked!!! So far, a sturdy bamboo stake and burlap twine is working, but I am just this close to going to Tractor Supply and getting some t-posts and bailing wire (kidding). You get the picture. 🙂
Hi Erin. Because of your You Tube shows on dahlias, i have started a few this year in pots. I live in MN zone 4, so will have to wait to plant then outside until June 1st. We have deer in our area and yard. Do they bother your dahlias? If so, what do you do to keep them from eating your plants! I love your our videos And blogs! Thanks.
In MN we need to dig them up in the fall. Can you tell us when to do this and how?
I live in zone 5…near Toronto Canada. First attempt with dahlias.potted and sprouting.put in shed …out in warmth in day and away at night..already have staked.getting excited.Thanks and love your videos. HAPPY GREEN THUMBING. WENDY
Hi Erin, I’m in southern Ontario and have also started some in pots this year due to your videos! I’m worried tho as they are very tall and I believe light deprived. I have pinched them back I just don’t know if I should leave them and get them outside as soon as I can? Love your videos btw, good luck with all your projects! Michelle
jDo you have to dig up Dahlia ? When do you dig them up
Oh I have tried and tried to grow these flowers I still can’t ?. But I sure can grow orchids lol.
Hi Erin,
I am familiar mostly about you from your you tube channel but thought it would be good to ask my question about my dahlia dilemma here. I am kinda new to growing dahlias. I saved tubers from last year and planted the few I have in pots this spring and moved them in and out of my greenhouse. They were amazing!! Got so excited to see them thrive. WEll, I fertilized them and now I have only foliage and there are no blooms. A good learning experience for sure. I wondered if I prune them heavily will they possibly bloom this year? I am sure you can help me so thank. you in advance.
Janie
Hi there just got your story on goggle nice to see dahlia from another country. I have just played my show dahlias .Regards Dennis
Thank you for your great articles. Some of my dahlia tuber frin last year look a bit pruny! Can they be potted and grow successfully, or should I try to bring them back to plumpness first? Any thoughts are appreciated.
Good morning. I live in NY and have had Dahlias for years. This seems to be a great summer for them. Last year they were so slow to bloom and then I lost them all to an early frost before many had even opened! I have 40 with 1/2 in pots. I winter my Dahlias and have had great luck. The pots are so simple (just need the room for storage).
Well, I’m bummed because I decided to fertilize all my Petunias and Dahlias early this morning and in error gave my 4 healthiest looking Dahlias the Petunia food! I am wondering if I’ve harmed my precious flowers!
I would appreciate any comments or advice you can give me. These Dahlias are just about to bloom. I’ve fed all of them once so far with Miracle Gro boom booster.
Thank you in advance!
Linda.
Out of four dahlia bulbs two are in pots growing beautifully. The other two planted on the ground in mid-may did not sprout at all. The bulbs are in good state. Should I dig them up and replant them in pots? I hate to see them wasted. I tried gently with my fingers to feel any sprouts. But none. Advice please.