(Question)
The front flower bed contains a very old rose shrub. It was over 6 feet tall and was hard pruned back to about 3 feet in November. How do we maintain the rose to bring it back to health/bloom?
(Answer)
The key to a healthy rose bush includes the following:
- Pruning: Generally, the rose shrub should be pruned in early spring, at the end of its dormant season, which is April or May in Toronto, after the danger of a hard frost has passed. This is when the leaf buds are starting to swell and just prior to the start of new growth. As you pruned the shrub back in November, the rose may not bloom this year. Also, the type of annual pruning (hard, moderate, light) depends on the type of rose. If you’re not sure of the type or rose, watch the shrub for a season. If it blooms on the new growth it sends out in the spring, prune it when it is just about to break dormancy (as above). If it blooms early (i.e., on last year’s canes), wait until after it flowers to prune it.
- Removing dead-looking branches/weak stems: This should be done in early spring.
- Ensuring good soil: Amend the soil with compost and well-rotted manure to provide a good growing environment. This provides nutrients for the rose plant, and also feeds the helpful organisms found in the soil.
- Fertilizing: Use a fertilizer In particular, phosphorus is needed for flowering (this is the centre number of the fertilizer) – e.g., A granular fertilizer ( 6-12-6) is an easy way to feed the rose bush. Follow package directions. It is recommended that the plant be fertilized in early spring, then just prior the blooming in June and a third time, in July. To ensure the plants can harden off before winter, fertilizing later than July is not recommended.
- Watering: Water the plant deeply once weekly to ensure the entire root area is wet. If the top 5-10 cm (2 – 4 inches) of soil is dry, then water the plant.
- Siting: Roses need full sun (at least 6 hours daily) in order to bloom. If, over the years, the area the rose bush is located has become shady (e.g., due to the growth of adjacent plants), see if you can alter the site (e.g., by cutting back other plants) to ensure full sun for the rose shrub. If not, the shrub may need to be moved.
- Good care throughout the blooming season: Deadhead faded blooms, get rid of suckers, and continue to remove canes/branches that grow towards the middle of the bush (the latter could compromise air circulation and access to light).
- Diseases and pests: Watch for insects or diseases. As it sounds like the plant has been neglected for some time, it may be weakened such that it cannot fight off diseases/pests as well as it should. These include rose galls (swellings caused by the larvae of small insects that lay eggs in rose stems), cankers, stem boring sawfly (the larvae can cause hollow stems), black spot (on the leaves), Japanese beetles (pick these critters off by hand and drop them in a container of soapy water), aphids, powdery mildew. If you find a problem, take a photo to your local gardening centre for identification.
- Protect yourself – use rose gloves: These are longer than the usual gardening gloves and will cover your arms, protecting them from thorns.
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