What fertilizer should be applied during the flowering period of rhododendrons to extend the flowering period?

Potted rhododendrons have limited space in the pot and relatively small nutrient reserves, so they need regular fertilizing. Rhododendrons themselves also quite like fertilizer, but fertilizing requires strictly controlling the concentration to avoid fertilizer burn caused by excess. To make the plant grow more vigorously and bloom beautiful flowers on schedule, topdressing is usually carried out during the growing season, before flowering and after flowering, and even during the flowering period, if necessary, appropriate topdressing can also be done. So, what fertilizer should be applied during the flowering period of rhododendrons?

But fertilizing during the flowering period is usually done as a supplement when pre-flowering fertilization was insufficient. To promote flowering, the main thing is still to provide enough fertilizer before flowering, during the bud differentiation and bud development stages. Generally, from the start of flower bud differentiation to successful flowering, rhododendrons often need to go through 8-9 months. Timely topdressing during this period is a fairly key step for promoting the growth of rhododendrons, making them grow lush branches and leaves, and producing more and larger flowers.

But note that if we did not give the rhododendrons enough topdressing before flowering, the flowering result of the original plant will be unsatisfactory, and there may be few flowers or even no flowers. Therefore, we need to appropriately topdress during the flowering period as a supplement to stimulate the plant to bloom. Flower-promoting fertilizer is generally mainly phosphorus and potassium fertilizer, so it is recommended to use potassium dihydrogen phosphate solution for spraying. But it is best to use the spray method and evenly spray the diluted fertilizer solution on the plant.

But if we already applied enough fertilizer before flowering, especially if enough nutrients were prepared during the bud differentiation and bud development stages, then rhododendrons generally do not need fertilizing during the flowering period. Because the nutrients were already sufficient and enough to support the rhododendrons in flowering successfully, hastily topdressing again would instead be counterproductive. It may not only cause rampant growth of branches and leaves and thereby inhibit flowering, but may also cause flower drop and may even lead to fertilizer burn.

When topdressing potted rhododendrons during the flowering period, it is generally done during the bud differentiation and bud development stages, and phosphorus and potassium fertilizer should be the main topdressing, with as little or no nitrogen fertilizer as possible. When nutrients are sufficient, try not to topdress during the flowering period, and continue topdressing after flowering to promote the plant's recovery and achieve a rejuvenating effect. In the 2-3 months before flowering, appropriate topdressing can be done several times, and after bud differentiation is complete, fertilizing should be stopped in time; after flowering, topdressing 2-3 times is enough.