We brought in our Dipladenia last winter and kept it indoors. We took it out on our terrace after spring in the West End and fertilized it, but it is not flowering and has no buds. The leaves are very green and lush.
How do I get it to flower again. It gets a least 4 hours of sun every day. We have it in the same spot as last summer ( North East)
Dipladenia should be overwintered in a warm, sunny spot and fertilized once a month or so starting in late February “to encourage new growth and bloom in anticipation for its return outdoors in May”. (From an earlier post, Ask a Master Gardener. Overwintering large Rio Dipladenia in container.) It is not clear if you started getting the plant ready in February – if not, it may take several weeks for the plant to bud and bloom now that it’s outside.
It sounds like you are taking good care of the plant, however, here are some additional factors to consider that might help with stimulating those buds/blooms:
Full sun: Although the plant likely bloomed well for you last summer in that same spot, it performs best in full sun, which means sun for at least 6 hours a day. Moving the container to a sunnier space may do the trick.
Fertilizer: Fertilize every two weeks or so, using a water-soluble fertilizer. (From Mississippi State University Extension. Mandevilla and Dipladenia: Although similar flowers, one is vine, other is shrub). A balanced fertilizer, e.g., 20-20-20 NPK (=Nitrogen:Phosphorus:Potassium) should work, although a higher phosphorus ratio in a fertilizer (a higher middle number) increases the ability of a plant to flower, and promotes budding; if you use a high-phosphorus fertilizer, make sure to switch back to a balanced fertilizer after several weeks.
Soil: Dipladenia should be transplanted every couple of years, as soil may be depleted of nutrients and the plants may be too big for their pots. (See National Gardening Association. Shoots On Dipladenia – Knowledgebase Question. (Although this article is supposed to relate to plant shoots, it’s more helpful regarding nutrient issues)
All the best in encouraging your lovely Rio Dipladenia to bloom!
June 25 2024