Topping Dahlias

By Carroll McAllister and Deannie Anderson

Topping a dahlia is of utmost importance in growing a plant with blooms of the largest diameter and depth possible for the variety. It also keeps your plant shorter and bushier, and thus easier to maintain.

 

Suggested Number of Leaf Pairs
to be Kept on the Plant

Bloom Size Inches

Size Designation

Leaf Pairs

8 to 12 inches

A and AA

2 - 3

6 to 8 inches

B

3 - 4

4 to 6 inches

BB

4 - 5

Under 4 inches

M

4 to 6

over 3.5 inches

Ball

5

Specific recommendations are not made with respect to all other classifications. However, consider keeping leaf pairs in accordance with expected bloom size.

OPTION I

Under Option I the plant is topped while it is very small, just as it is developing the number of leaf pairs desired for its ultimate bloom size.

This option gives an early start to the development of the laterals to be nurtured and truncates the development of laterals that would later be discarded and, in theory, conserves the energy of the plant. Under this option, the point at which laterals emerge from the primary trunk is quite close to the ground.

The plant pictured on the right (Zorro an AA) has a pair of cotyledons (leaves that are not true leaves) and three pairs of true leaves. In this example, it will be topped leaving three leaf pairs (See table above).

 

To top this plant...

  • 1. Count the number of true leaf pairs from the bottom up to be sure you are at the correct position for topping.

In this case, the top, or tip, of the plant is between the third pair of leaves. The top to be removed can be seen in the center of the picture between the top pair of leaves.

 

  • 2. Then simply pinch out the center. Be extremely careful not to disturb the new growth on either side of what you are pinching.

Note how close to the ground the pairs of leaves are. This is the result of topping the plant when it is very small having developed only three true leaf pairs.

Continued on next page.


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