Plants, same pots now as last summer. Purchased separately, planted in 3 pots. Sat in a North window and blossomed
all winter. Spider mites treated with dish soap in a gal. of water, thorough spray then showered off. Roots seem ok. leaves bright green then turn brown, 1/2 developed flower(?)
Thank you for contacting the Toronto Master Gardeners regarding your Gerbera plants (Gerbera jamesonii). We are sorry you had difficulty submitting a photo. Based on the details you’ve provided we can give you some general information that may help with your situation. It sounds like you had these Gerbera plants outdoors last summer and brought them indoors over the winter where they thrived. You successfully treated them for spider mites and hardened them off before moving them outdoors where they are in the same pots as last year. Now you are seeing leaves that turn brown and flowers that don’t fully develop. Examine the underside of the leaves as well as the stems and flowers to be sure that there are no visible pests present. Spider mites are hard to see without magnification or tell-tale webs. They can cause leaf changes and deformity of plant parts. It is possible that you have a resurgence of spider mite infestation on your plants. This information from The University of Minnesota may be helpful for Spider mites. In addition, this information from Pennsylvania University Extension describes the symptoms of several common Gerbera plant diseases Penn State Extension. Both overwatering and under watering can can cause leaves to brown. Water plants when the soil feels dry 1-2 inches below the surface. Ensure your pots have holes in the bottom to provide good drainage. Watering early in the day and not in full sun will prevent leaf scorching and watering around the base of the plant, as opposed to overhead, will help to prevent the spread of disease from one part of the plant to another. Gerbera plants need sun but will benefit from some shade, especially if conditions are as hot and oppressive as they’ve been in the past week in Southern Ontario. Soil can sometimes be an issue. If you are using the same soil in the containers as last year, repotting with fresh potting mix may be helpful in eliminating any soil-borne pests or diseases. An application of organic fertilizer may also be helpful if the soil is depleted of nutrients. This information sheet with Gerbera care tips provides some helpful information Gerbera daisy .
We hope this information is helpful and wish you the best of luck with your Gerbera plants!
June 8, 2021