Coaxing roses to bloom requires some TLC
Proper mix of major nutrients and plenty of exposure to sunlight vital for plants to flower
Q Several years ago, I dug up three roses from a garden that was about to be bulldozed. One rose is in the garden, the other two are in pots. The plants have an abundance of healthy leaves, but have never bloomed.
A: Whenever roses and other flowering plants have plenty of healthy looking green growth and no flowers, a common cause is an over-abundance of nitrogen (N) in the soil, without balancing amounts of phosphorus (P) and potassium (K). Fertilizer labels indicate levels of each of these major nutrients in three numbers arranged in the N-P-K order.
Phosphorus and potassium are especially needed for stimulating bloom production. Trace elements such as iron and magnesium are also important. Seaweed meal (I use kelp meal) is rich in trace minerals and potassium.
Exposure to sunlight is also necessary for good flowering in roses.
There is another possible explanation for there being no bloom, though it’s a long shot, and most likely only if the roses had been long neglected before you retrieved them.
Sometimes, if roses aren’t regularly monitored, and they are budded plants — that is, propagated with a selected, named variety joined on to an understock — the understock will sometimes sprout and overtake the plant. Understock plants are chosen for qualities such as hardiness and vigorous growth, rather than for their flowering.
You can determine whether this has happened by brushing away some of the soil from the base of a plant to find a slight bulge above the roots — the budding site. If growth is emerging from below the bulge, the plant’s top growth will be that of the understock plant and not of the roses you were expecting.
That bulge, the bud union, should be one inch beneath the soil surface. This is the best depth for anchoring the plant and helping to prevent growth from below the bud union.