Bedding Plants Yellowing and Dying

Q. My newly installed Penta bedding plants are dying, and the leaves are turning yellow. They are getting plenty of water. Any ideas what is causing them to die so fast?

A. What are Pentas?

Pentas, sometimes called Star Clusters, are summer annuals grown as bedding plants for their color. The same as any other bedding plants, they don’t like unamended desert soils, bad quality landscape soils or desert landscapes. They abhor rock but grow best in soil amended with good quality compost each time they are planted.

Penta bedding plants are from hot, tropical Africa so they like the heat, must be planted in soils with good drainage and fertilized every six weeks because they love rich soils. They don’t grow well in cool or cold desert soils or planted without a good soil amendment. In fact, they suffer badly when temperatures dip to 40° F in the spring or fall so plant them only when you are confident temperatures are warm and getting hotter.

Always Amend Soil for Bedding Plants

            My guess is the soil used for growing the Pentas was poor quality to begin with or a poor quality soil amendment was added to it. If a poor quality soil or amendment was used, water drainage will cause root rot which will cause yellowing of the plants. If they were planted in February or March, they might have been damaged by cool or cold weather which can also cause yellowing.

            

Soil Pro is a bagged very rich compost available from viragrow in North Las Vegas. If the soil is amended with this compost no fertilizer will be needed for the planting season.

            Add enough good quality compost or soil amendment so that the soil is dark brown, and you can dig in the soil with a garden trowel easily. While amending soil for planting, throw in some 16 – 20 – 0 or comparable organic fertilizers to get their roots off to a good start and the plants established quickly.

Bedding Plants like Moist Soil

            Irrigate bedding plants like vegetable transplants; daily after they are established and twice a day during the two weeks of establishment. If this is a permanent bed for bedding plants, use half inch drip tubing about 12 inches apart for watering rather than the skinny laser tubing which tends to plug. Water with drip irrigation anytime. When using overhead sprinkler irrigation, water between 3 and 5 AM to minimize disease problems and water loss due to wind.

Rich Compost Doesn't Need Added Fertilizer

            If you use a rich, high quality compost then additional fertilizer won’t be needed for the first couple of months. After that, lightly fertilize bedding plants monthly with a high nitrogen fertilizer such as ammonium sulfate or blood meal. If a good compost is used as a soil amendment, then there are lots of nutrients in the soil already.