(Question)
I cannot for the life of me figure out why some of my Gerberas are dying while the others thrive. They are in a rectangular plantar box beside our front stairs. They get full sun (south facing) and are well watered (as needed).
They were planted at the same time. They have been fertilized every other week using the solution from Sheridan Nurseries.
The soil was well tilled before planting. And was topped up with some triple mix from Home Depot.
(Answer)
I’m sorry to hear that some of your lovely daisies have died. It’s not clear from the information you provided what might have killed the plants, but a few issues come to mind:
- Too close together? From your photo, it looks like the daisies were planted very close together, which could lead to competition between neighbours, and some flowers could thrive while others suffer. The plants should be around 30-45 cm (12-18 inches) apart, which permits lots of air circulation (making them less vulnerable to pests and disease) and room to grow.
- Soil compacting? For containers like planter boxes, potting soil should be used. Soil from the garden or triple mix is generally too dense for planters, so could compact and provide a hostile environment for plants. As well, drainage would likely be a problem, and Gerberas do best in well-drained soil. For more information, see the University of Illinois Extension’s Successful container gardens – using soil and soil mixes. From your description, the soil you used was nicely prepared, but I would suggest that you switch out the soil for potting soil.
- The right fertilizer? You mention that you fertilize the daisies every 2 weeks. It’s not clear what type of fertilizer you are using. Gerbera daisies like a fertilizer that is relatively low in phosphorus (e.g., 24-8-16 – which indicates the presence of Nitrogen (N), Phosphorus (P), Potassium (K) in a 3-1-2 ratio) and as the plants can be deficient in the micronutrients iron and manganese, a fertilizer that also contains these elements would be a good idea.
- Watering? The best time of day to water is the morning, as the plants and soil can dry throughout the day. This decreases susceptibility to fungal disease.
- Too much sun? Although Gerbera daisies are native to South Africa, they don’t appreciate the hot, hot sun. It’s been a very warm summer so far in the GTA, and placing the container in a spot where they will receive morning sun and afternoon shade, especially on hot, dry days, should help them thrive. You mention that your planter is located near stairs – in some cases, stone walls (including steps) very close to the daisies can reflect heat back to the container, making the spot less than ideal.
- Planted too deeply? When placing the daisies in the planter, be careful to plant them at the same depth as in the original pot. If planted too deeply where the crown is very close to the soil line, the daisies are susceptible to a fungal disease called crown rot. Plants might look fine one day and decline rapidly the next.
All the best in keeping your Gerbera daisies healthy and happy all summer long!
June 28 2021