Cut Flower Updates: August 1, 2025

Frequent rainstorms and high temperatures this summer have made a perfect setting for weeds to flourish in the flower field. A combination of annual and perennial weeds can compete with newly planted seedlings and established plants for space, sunlight, water, and nutrients, causing poor establishment and impacting yield and harvest.

Large crabgrass (Digitaria sanguinalis) is a common summer annual weed in cut flower fields and high tunnels. It has a prostrate growth habit, with stems that spread along the ground. The roots are fibrous and can usually be removed by hand or with the help of a soil knife. Care should be taken to remove plants before they set seed.

Field bindweed (Convolvus arvensis), shown above spreading across a bed and pathway, is a vining perennial weed in the morning glory family with a deep, fibrous root system. The leaves are arrowhead-shaped. It spreads rapidly, creating mats of tangled vegetation. Once established, it is very difficult to eradicate. Hand pulling is an effective method for controlling seedlings and young plants. Tarping, including solarization and occultation, can help reduce bindweed pressure.

Porcelain berry (Ampelopsis glandulosa) is a woody, invasive vine that can be an issue on woodland-adjacent farms. The leaves are deeply lobed and grape-like in shape. Greenish-white flowers bloom in summer, yielding small blue and purple berries. This plant resprouts readily from established root systems, which often require hand tools or a shovel to remove from the soil.

Other issues we're seeing right now include bacterial leaf spot on zinnia, powdery mildew on lisianthus, and Japanese beetles feeding on dahlias.

We'll cover these in more detail in the coming weeks. For now, enjoy the break in the heat this week! Reach out to Margaret at mfp5667@psu.edu if you have a weed, pest, disease, or production issue on your flower farm that you’d like us to cover in our weekly updates.