How does bulb sizing work and what should I look for?

Created by Kinsey Harris, Modified on Mon, 06 Jun 2022 at 02:54 PM by Kinsey Harris

Since most of our bulbs come direct from our growers and farms in Holland, bulb sizes within the industry are usually given in centimeters and are usually labeled as such by the "cm" notation to indicate the circumference of a bulb (note there are 2.54 centimeters in an inch.) 

To measure a bulb, wrap a tape measure around widest part of the bulb and measure. The following chart provides a guideline as to what are the minimum and maximum sizes of fall planting bulb varieties.

 

Variety

Top size

Minimum acceptable size

Notes


In centimeters

In inches

In centimeters

In inches


Tulips

12/+ cm

4.72

10 cm

3.94


Narcissus and Daffodils

16/+ cm

6.3

12 cm

4.72


Hyacinths

19/+ cm

7.48

14 cm

5.51

Top size hyacinths are usually reserved for indoor forcing. In the garden look for hyacinths size 15/16 cm. Larger hyacinths have a tendency to fall over from the weight of the flower.

Large Flowering Crocus

9/+ cm

3.54

7 cm

2.76


Specie or Snow Crocus

5/+ cm

1.97

4 cm

1.57


Dutch Iris

9 cm

3.54

7 cm

2.76


Specie Iris

6 cm

2.36

4 cm

1.57


Large Allium

20/+ cm

7.87

19 cm

7.48

Includes following varieties: Giganteum, Lucy Ball, Stipitatum, Globe Master

Medium Allium

14/+ cm

5.51

12 cm

4.72

Include following varieties: Aflatuense, Christophii, Karataviense, Rosenbachianum, Schubertii, Ivory Queen

Small Allium

4 to 6 cm

1.57 - 2.36

4 cm

1.57

Includes following varieties: Moly, Ostrowskianum, Neapolitanum, Sphaerocephalon

Fritillaria Imperial

24/+ cm

9.45

22 cm

8.66


Amaryllis

34/+ cm

13.39

24 cm

9.45


Jumbo Amaryllis

42/+ cm

16.54

n/a

n/a

Only a few varieties of Amaryllis grow larger than 34 cm

Paperwhite Narcissus

17/+ cm

6.69

14 cm

5.51

Ask your local retailer for Jumbo paperwhites.

Oriental Lilies

18 cm

7.09

16

6.30


Asiatic Lilies

14/+ cm

5.51

12 cm

4.72

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