Boron Tolerance Limits for Ornamentals (a)
Maas (1990)
- Very Sensitive -
| Common Name |
Botanical Name |
Threshold (b); mg/L |
| Oregon grape |
Mahonia aquifolium |
<0.5 |
| Photinia |
Photinia x fraseri |
<0.5 |
| Xylosma |
Xylosma congestum |
<0.5 |
| Thorny elaeagnus |
Elaeagnus pungens |
<0.5 |
| Laurustinus |
Viburnum tinus |
<0.5 |
| Wax-leaf privet |
Ligustrum japonicum |
<0.5 |
| Pineapple guava |
Feijoa sellowiana |
<0.5 |
| Spindle tree |
Euonymus japonica |
<0.5 |
| Japanese pittosporum |
Pittosporum tobira |
<0.5 |
| Chinese holly |
Ilex cornuta |
<0.5 |
| Juniper |
Juniperus chinensis |
<0.5 |
| Yellow sage |
Lantana camara |
<0.5 |
| American elm |
Ulmus americana |
<0.5 |
- Sensitive -
| Common Name |
Botanical Name |
Threshold (b); mg/L |
| Zinnia |
Zinnia eleganus |
0.5-1.0 |
| Pansy |
Viola tricolor |
0.5-1.0 |
| Violet |
V. odorata |
0.5-1.0 |
| Larkspur |
Delphinum sp. |
0.5-1.0 |
| Glossy abelia |
Abelia x grandiflora |
0.5-1.0 |
| Rosemary |
Rosmarinus officinalis |
0.5-1.0 |
| Oriental arborvitae |
Platycladus orientalis |
0.5-1.0 |
| Geranium |
Pelargoium x hortorum |
0.5-1.0 |
- Moderately Sensitive -
| Common Name |
Botanical Name |
Threshold (b); mg/L |
| Gladiolus |
Gladiolus sp. |
1.0-2.0 |
| Marigold |
Calendula officinalis |
1.0-2.0 |
| Poinsettia |
Euphorbia pulcherrima |
1.0-2.0 |
| China aster |
Callistephus chinensis |
1.0-2.0 |
| Gardenia |
Gardenia sp. |
1.0-2.0 |
| Southern yew |
Podocarpus marcophyllus |
1.0-2.0 |
| Brush cherry |
Syzygium paniculatum |
1.0-2.0 |
| Blue dracaena |
Cordyline indivisa |
1.0-2.0 |
| Ceniza |
Leucophyllus frutescens |
1.0-2.0 |
- Moderately Tolerant -
| Common Name |
Botanical Name |
Threshold (b); mg/L |
| Bottlebrush |
Callistemon citrinus |
2.0-4.0 |
| California poppy |
Eschscholzia californica |
2.0-4.0 |
| Japanese boxwood |
Buxus microphylla |
2.0-4.0 |
| Oleander |
Nerium oleander |
2.0-4.0 |
| Chinese hibiscus |
Hibiscus rosa-senensis |
2.0-4.0 |
| Sweet pea |
Lathyrus odoratus |
2.0-4.0 |
| Carnation |
Dianthus caryophyllus |
2.0-4.0 |
- Tolerant -
| Common Name |
Botanical Name |
Threshold (b); mg/L |
| Indian hawthorn |
Raphiolepis indica |
6.0-8.0 |
| Natal plum |
Carissa grandiflora |
6.0-8.0 |
| Oxalis |
Oxalis bowiei |
6.0-8.0 |
Notes:
(a) Species listed in order of increasing tolerance based on appearance as well as growth reduction.
(b) Boron concentrationsexceeding the threshold may cause leaf burn and loss of leaves.