Why Oleander Not Flowering

Q. I have a dozen, full-sized oleander plants I put in last year. I fertilized them with a 20 – 20 – 20 fertilizer. They are growing great but they rarely flower. Am I missing something or is it the fertilizer?

Flowers of a full sized oleander shrub. Flowers grow on "current seasons wood". In other words, the flowers form on stem growth this year, not last.

A. It will probably take about three years for them to really start flowering a lot with that fertilizer and regular irrigation. Oleander loves irrigation water. It also loves fertilizer. The combination of regularly watering and applying a good fertilizer results in dark green leaves with lots of new succulent growth. This new growth is not yet fully mature. When it does flower a little bit later in its life, the show will be spectacular. Just be patient.

If oleander is cut back hard, it will grow fast to reach close to its size before it was cut back. Some people call this its "root to shoot ratio". When the plant has an existing large bunch of roots and the top is removed, the sbrub grows very rapidly until it gets back close to its original size. It doesn't waste time and energy flowering yet. But it will when it gets larger.

            The nitrogen in the fertilizer is the first 20. The second and third 20s stand for the phosphorus and potassium in the fertilizer. The middle 20, the phosphorus, encourages flowering but it also encourages the roots to get firmly established in the soil. Flowers will be produced on new growth. The more stems of new growth, the more flowers it produces. If the oleander is lush and bushy, it will be full of flowers and bloom when it’s ready.

Dwarf oleanders stay small and flower at a smaller size than standard sized oleanders. When oleanders are young make sure there is plenty of phosphorus in the amended soil and then just feed it nitrogen fertilizer to get it big. This shrub will start flowering when it's supposed to.