Plant (or Pot) Before You Pinch
As dahlia growers across North America nurture their first cuttings and seedlings of the season, the same questions start popping up in dahlia groups on social media:
“Is it time to pinch? When should I pinch? Where should I pinch? Can I pinch more than once?”
Based on countless photos I’ve seen accompanying these questions, I’m convinced that many growers pinch their dahlias far too early. Here’s why.
Whether a young dahlia has grown from a cutting or a seed, its root system is still fairly shallow—often just an inch or two deep, depending on the size of its first container. To develop a strong root system that will both anchor and nourish the plant as it matures, you need to gradually introduce it to a deeper position in the soil.
The Right Way to Pot Up Young Dahlias
Prepare the Plant – Strip the bottom one or two pairs of leaves from the dahlia before potting it up. Use your fingernail to gently pull the leaves down and away from the stem. You can leave the root ball intact or gently spread the roots to prevent entanglement as the plant grows.
Prepare the New Pot – Add the right amount of soil to the bottom of a larger pot so that the young dahlia settles in with the soil level just below its new bottom set of leaves.
Plant and Water – Fill around the root mass with soil, gently water it in, and you're done!
Step 1
This dahlia cutting is about 4 weeks old. Its roots have developed nicely inside its 4-inch (10 cm) pot and it is ready to be potted up into a larger 6-inch (15 cm) container.
Step 2
When this cutting was initially potted up from the small cell where it was rooted, I pinched the bottom set of leaves and covered them with soil. We are going to do that again in the following step.
Step 3
Gently remove the lower 1 or 2 sets of leaves (here I am removing two sets). The tissue where these leaves grew will form new roots–and eventually tubers–when they are covered with soil.
Step 4
After preparing the soil in the larger pot, position the dahlia so that the soil will be level with the lowest remaining pair of leaves. Note that the soil in the new pot covers the portion of the stem where we stripped leaves in Step 3 (above).
Why This Matters
New roots will grow from the meristem tissue where the leaf nodes were buried. Many of these will swell into tubers , helping to anchor and feed the plant while ensuring an easy-to-divide tuber clump at the end of the season.
By the time this dahlia is ready for the garden, it will have reached 18-24” (45-60 cm) in height with 5-7 leaf pairs . At planting time, I’ll strip off another 1-2 pairs of leaves and position the plant so those leaf nodes are covered with soil.
When to Pinch
Only after the dahlia has been planted in the garden—when it has reached its final depth—should it be pinched. The correct spot? Above the fourth or fifth pair of leaves. This promotes a bushier plant with multiple strong flowering stems.
The Problem with Pinching Too Early
Pinching a small dahlia prematurely removes apical dominance and triggers growth from multiple tips at once. When this happens before the root system is well-established, the plant becomes top-heavy and weakly anchored .
By potting up (and planting) dahlias at the proper depth —and waiting to pinch until the final leaf pairs are set—you’ll ensure your dahlias are just as strong underground as they are above!
