Whether you’ve ordered new dahlia tubers or have some stored from last year, it’s always a smart move to check they’re viable before planting. In the spring, it’s common to see dahlia tubers damaged by traffic in your post system, garden center, or garage.
A single tuber is often detached from the main cluster, or a dahlia tuber with a damaged neck can be seen. Some will still have everything they need to grow, giving you an extra Dahlia plant for free; others will not be viable and will simply rot in the ground, wasting your time and space in the garden.
Fortunately, there is a very easy way to tell if a dahlia tuber is viable. These lovely flowers don’t come cheap, so it’s a trial worth doing before planting dahlia tubers.
How to tell if a Dahlia tuber is viable
1. Check that the crown is intact
If a tuber has detached from the main cluster, look to see where it has detached. A viable dahlia tuber has three parts: the plump, fleshy body where its energy is stored; a knob at the top called the crown, and a narrower neck connecting the two.
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Take a look at these tubers – they all have a crown of knobs at the top of their necks, and this is where the stems will grow from. Different varieties come in different shapes, but all should have a woody collar at the top of the neck.
Thus, if a tuber has fallen below this very important one crown – and this is quite common as the necks are so narrow – it is not sustainable. The rest of the cluster will be fine, but not that damaged, detached tuber.
You can see here how all the crowns are connected to last year’s stem. Planting this cluster as a whole will grow a large, strong plant, but each tuber has what it takes to survive on its own, even if divided, as long as its all-important crown is intact.
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2. Look for an eye
If the crown is intact, the next stage is to look for an eye. This is the point on the crown from which the stem grows, and there may be more than one.
If your tuber is still inactive – and if you recently bought yours, it may still be, even in May, as they are often kept in cold storage – then the eye will look like a small round bump, pimple or wart. It will be the same color as the crown, but slightly raised. If you can’t locate an eye, try cleaning off the old soil with a dry brush, then slowly rotate the crown under a desk light and a shadow of the raised area may reveal one.
The eyes can also be very prominent. Once a tuber awakens from dormancy, the eyes begin to swell and some may turn pink or green in color. The eye may even have sprouted and you will see the spin.
If your tuber has at least one eye, it’s good to plant.
3. Press the tuber
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If there is no eye mark, give the tuber body a gentle squeeze. If it feels at all soft or mushy, throw it away.
4. Give him one last chance
If the tuber body is firm, you can give your tuber one last chance by placing it horizontally in a tray of barely moist potting mix and just covering it with a little more soil. Keep it in a warm, light spot that is at least 65°F and within two weeks you should see at least one stem growing from the crown. If you see nothing after three weeks, examine the tuber again. You should at least be able to spot some swollen eyes at this point, so if you can’t, consign your tuber to the compost pile.
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What about tubers that are still attached?
Clumps of tubers still attached to last year’s stem(s) will have their crowns intact so are good to plant. Just give each tuber a gentle squeeze, and if you discover one that feels moldy, remove it from the cluster by cutting at the neck with hand pruners.
Don’t worry if some tubers have shriveled. As long as they’re stable, they’re probably fine.
What if the tuber neck is just damaged?
It is common to see tubers still attached to the main cluster but with a damaged neck. If it’s just the skin that’s broken, the damage is cosmetic and the tuber is probably fine. However, if the damage is deeper and the tuber is hanging by a few fibrous threads, it is best to cut it at the neck with hand pruners.
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The queen of saucer dahlias, ‘Cafe au Lait’ grows dainty 8-10 inch blooms, lovely in a cottage garden.
This compact beauty grows well in containers, producing a dazzling blend of fiery accented petals.
This bold dahlia grows 3–4′ tall, bringing drama to any border with its dark petals. this price is for 5 tubers.
