Sweet peas, Lathyrus odoratus, are ornamental vining annuals native to Mediterranean regions and suited to cultivation in USDA Hardiness Zones 2 to 11.
They prefer full sun to partial shade and fertile, moist, well-draining soil.
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Our guide to growing sweet peas has all you need to know to enjoy plants in the home garden.
This article zeroes in on nine reasons why plants may fail to bloom and what you can do to avoid or remedy them.
Here’s what we’ll cover:
7 Reasons Why Sweet Peas Fail to Bloom
1. Bud Drop
Bud drop is not a disease but a phenomenon in which buds drop off suddenly, for no apparent reason.
Since sweet pea stems are fragile, adverse environmental conditions, such as a strong gust of wind, sudden temperature change, or excessive rainfall, may cause them to turn yellow and fall off.
If your plant experiences bud drop, cut the budless stems back to their point of origin. If the temperature stays below 80°F, new buds should appear.
See our guide to sweet pea bud drop for more information.
2. Disease
L. odoratus is somewhat disease prone. Conditions that may adversely affect flowering include anthracnose and powdery mildew – two types of fungal disease.
Glomerella cingulata fungi cause anthracnose. The first symptom is white spots on the flowers, leaves, and stems. As the disease progresses, the affected plant tissue withers and dies.
To address an outbreak, remove damaged foliage and dispose of it in the trash.
Treat the remaining foliage and soil with neem oil.
Bonide Neem Oil
Bonide® Neem Oil is available from Arbico Organics in quart and gallon ready-to-use sprays and a pint-sized concentrate.
Microsphera alni fungi cause powdery mildew, a grayish-white, fuzzy coating most visible on the leaves. The pathogen can penetrates buds and flowers, causing deformity and a failure to open as expected.
Remove affected portions of the plant and spray the rest of the foliage and stems with neem oil.
