Sweet pea shrubs are dainty evergreens that bloom year-round. These shrubs make a good addition to borders in warm climates, and are also good in patio pots. Their purple or mauve blooms are bouquet favorites. However, like other plants, they are also prone to yellowing and disease.
Why is my sweet pea shrub turning yellow?
Your sweet pea shrub may be turning yellow due to overwatering, or watering from a cold hosepipe. It may also be due to compost that is too rich and is burning the plant’s roots.
Sweet pea shrubs only need to be watered once a week, but be sure to maintain balanced moisture throughout the growing season. These plants do not like hot weather, so water them regularly in the early morning during summertime to prevent buds from dropping and to prevent them from getting scorched.
Why are my sweet peas’ leaves turning brown?
Sweet pea leaves may turn brown because of Pythium root rot that often affects these plants. The plants may appear light brown and the stems may feel mushy.
Fusarium root rot, on the other hand, causes foliage to turn yellow and eventually gray, while the stem becomes dark brown. To control these diseases, plant your sweet pea shrubs in areas that have good drainage and apply fungicide as a seed treatment.
Why is my sweet pea shrub turning white?
Sweet pea shrubs may turn white due to powdery mildew. Round, white, powdery spots and coating appear on the leaves, stems and pods. This is caused by fungal spores that germinate on the dry leaf surfaces when humidity is high. This is common during late summer or fall, but it does not cause major damage to the plants.
Powdery mildew can be treated with Systhane fungicide which should be sprayed for the rest of the flowering season.
Other conditions that may affect your sweet pea shrub
Bud drop
Bud drop is a condition, not a disease, caused by variations in temperature such as hot days and cold nights. The buds may turn yellow or green and eventually fall off when touched. There is no cure for this other than to wait until the weather settles and the nights become warmer. Avoid feeding the plants until they start to set buds and flower.
Bud drop may also be caused by watering the plants with a cold hosepipe, so make sure only to use water that has stood for at least a day.
Pollen beetle infestation
Pollen beetles tend to invade sweet pea shrubs and get inside the keel of the flowers. These bugs usually come from rapeseed fields and are also called rape beetles. You can control these insects by placing cut rapeseed flowers in your shed or garage so the bugs will transfer to them. A yellow bucket of water among the plants in the garden will also attract these bugs, which eventually fall and drown in the water.
Caring for your sweet pea shrub
Sweet pea shrubs only need minimal care and can survive despite the absence of supplemental irrigation. These plants thrive if watered regularly, while those grown in containers require more water. They bloom the whole year round, and should ideally be given a general-purpose fertilizer during the spring and fall seasons.
Sweet pea shrubs require little or no pruning and a light trim at any time of the year is all that is needed to control their size. The stems of older shrubs may become woody, but you can always cut them to about 10 inches above the ground and allow them to regrow. You may also opt to let it grow naturally.
You can also let the shrubs grow into small trees. Remove all except one vertical stem and take away the side branches on the lower half to two-thirds of the trunk while the plant is still young. Species like Polygala can be propagated from seeds that fall to the ground and take root if the plants are not deadheaded regularly. Hybrids are sterile and you can propagate them from softwood cuttings taken in spring or fall.
Sweet peas in containers need to be planted with at least 10 inches of space around each plant. The containers should be as deep as possible. Since newly-planted sweet pea plants are very hungry and thirsty, they will all fight for the nutrients in the containers if they are planted too close to one another.
Conclusion
Sweet pea shrubs turning yellow is usually attributed to overwatering or being watered from a cold hose pipe. These plants only need to be watered once a week, but make sure that the moisture balance is maintained throughout the growing season. Sweet pea plants do not like hot weather, so make sure that during these periods they are watered during the early hours of the day.
Image: istockphoto.com / Kamila Kozioł