Herbaceous Bulbs : Summary
Bulbs are specified with reference to the following criteria:
| CIRCUMFERENCE |
CONDITION |
OTHER FACTORS |
General requirements regarding CONDITION, are given in Part 1. With regard to CIRCUMFERENCE, bulbs, corms and tubers are very variable and the following table (taken from BS 3936 Part 9, gives information for the main types. Further information, for other species, hybrid s or varieties can be obtained from specialists.
|
Species
|
Min.
circ'ference
|
Grades
|
|
Allium
moly
|
3
|
3/4;
4/5; 6/+
|
|
Anemone
blanda
|
4
|
4/5;
5/6; 6/7; 7/8; 8/+
|
|
Chionodoxa
|
4
|
4/5;
5/6; 6/+
|
|
Colchicum
spp.
|
13
|
13/14;
14/15; 15/+
|
|
Cyclamen
hederifolium + similar spp.
|
6
|
6/8;
8/10; 10/12; 12/+
|
|
Eranthis
|
3
|
3.5/4;
4/5; 5/+
|
|
Fritillaria
imperialis
|
18
|
18/20;
20/22; 22/+
|
|
Fritillaria
meleagris
|
5
|
4/5;
5/6; 6/+
|
|
Galanthus
nivalis
|
4
|
4/5;
5/6; 6/+
|
|
Hyacinthus
hybrids
|
14
|
14/15;
15/16; 16/17; 17/18; 18/19; 19/+
|
|
Lilium
candidum
|
16
|
16/18;
18/20; 20/22; 22/+
|
|
Muscari
armeniacum
|
6
|
6/7;
7/8; 8/9; 9/10; 10/+
|
|
Narcissus
large garden hybrids
|
10
|
10/12,
12/14, 14/16, 16/+
|
|
Narcissus
smaller hybrids
|
10
|
10/12;
12/14; 14/+
|
|
Narcissus
bulbocodium and other small spp.
|
4
|
4/+;
4/5; 5/+; 5/6; 6/+
|
|
Narcissus
pseudonarcissus and other larger spp.
|
7
|
7/+
|
|
Scilla
siberica
|
6
|
6/7;
7/8; 8/+
|
|
Tulipa
garden hybrids; hybrids of T. fosteriana and T. kaufmanniana
|
10
|
10/11;
11/12; 12/+
|
|
Tulipa
praestans and cultivars; T. eichleri and cultivars
|
8
|
8/9;
9/10; 10/+
|
|
Tulipa
small spp. including T. kaufmanniana; T. tarda; T. turkestianica
|
5
|
5/6;
6/7; 7/+
|
The largest grade is usually referred to as Topsize and can be specified as such. For certain species, for biological reasons, it may be preferable to specify a smaller rather than a larger bulb or corm, e.g Cyclamen spp., Gladiolus spp. Also it is worth noting that smaller sizes are cheaper and often very satisfactory in projects where flowering in the first year after planting is not a priority.
Bulbs are usually graded using Round Riddle or Long Slot methods. The Round Riddle is appropriate for bulbs which are typically spherical about their circumference but less exact for Narcissus Garden Hybrids, whose bulbs are more ellipsoid. In Britain these Narcissus bulbs are usually graded using the Long Slot method which gives a more exact circumference measure. Due to these differences, Narcissus Garden Hybrids grown in Holland tend to be grade sizes larger than their British counterparts. It is important to consider the provenance of the bulbs in this specification
NarcissusTete a Tete, 10/11 |
Muscari armeniacum, 7/8 |
Narcissus Garden Hybrids, 12/14 |
Eranthis hymalis, 4/5 |
Crocus 'Zwanenburg Bronze', 5+ cm |
TULIPA Single early, 11/12 |