|We have a climbing rose that has not produced a flower this year, though it is huge and climbing up the trellis. What can we do to help it bloom?|
|Climbing roses bloom on new stems that grow on old wood. Pruning them back in late winter or early spring will encourage new flowering stems. If you didn't prune this past spring, most of the new growth will be at the ends of the main canes instead of all along new lateral stems, which produce the most flowers.
To flower freely, roses require full sun. Are your plants receiving at least 6 to 8 hours of sun daily?
Since the plants seem healthy otherwise, it's possible they might be missing essential nutrients. Nitrogen, phosphorus, and potassium are the three major nutrients for all plants. (They correspond to the three numbers on fertilizer packages.) Nitrogen promotes growth of green leaves. It sounds like your plants are getting plenty of that. Phosphorus is essential for blooms. Roses are heavy feeders during their bloom period. To give them a boost, you may want to apply a fertilizer formulated especially for roses. Roses also benefit from applications of greensand, which contains potassium. Just be sure to avoid feeding them with a high-nitrogen fertilizer, which will encourage foliage growth at the expense of flowers.
In general, horizontal canes produce more flowers than vertical canes, so you might try encouraging young canes to grow horizontally by gently tying them to the trellis.
Also, keep the plants consistently moist and mulch with 2 to 3 inches of compost to help maintain soil moisture.