Spacing

Spacing and light levels drastically affect plant height. Too close of spacing and poor light conditions stimulate undesirable stretching of internodes. Even the use of plant growth retardants cannot overcome the reduction in quality resulting from close spacing. Poinsettia plants can be spaced pot to pot after they have been transplanted into the final container. As the plants grow, they will require proper spacing to avoid lower leaf yellowing and leaf loss due to overcrowding. Plants which are spaced too close will stretch excessively, resulting in plants which have weak stems that easily break during shipping.

Stretching of poinsettias because of too close of spacing.
Click on image for larger version. (image © Brian Whipker, NCSU)

Overcrowding can cause lower leaf yellowing and leaf loss.
Click on image for larger version. (image © Brian Whipker, NCSU)

The recommended plant spacing varies by pot size, the number of plants per pot, and if the plants are pinched or non-pinched. Although greater spacing equates into greater overhead cost per plant, it can increase plant quality and reduce growth retardant costs. Remember that reducing production cost does not make money--maximizing profitability does.

Pot Size

Plants

(no./pot)

Pinched (P) or Nonpinched (NP)

Spacing

Area / Pot

inches

cm

inches

cm

ft²

m²

4

10

1

P

9 x 9

23 x 23

0.56

0.05

4

10

1

NP

9 x 9

23 x 23

0.56

0.05

5

13

1

P

12 x 12

30 x 30

1.00

0.09

5

13

2

NP

12 x 12

30 x 30

1.00

0.09

6

15

1

P

13 x 14

33 x 36

1.26

0.12

6

15

2

P

15 x 15

38 x 38

1.56

0.15

6

15

3

NP

15 x 15

38 x 38

1.56

0.15

6

15

4

NP

17 x 17

43 x 43

2.00

0.19

7

18

1

P

17 x 17

43 x 43

2.00

0.19

7

18

3

NP

17 x 17

43 x 43

2.00

0.19

7

18

5

NP

19 x 19

48 x 48

2.51

0.23

7

18

7

NP

22 x 23

56 x 58

3.50

0.33

Source: J.M. Dole and H.F. Wilkins. 1999. Euphorbia, p. 339. In: Floriculture Principles and Species.