How to keep rose bushes healthy

Frank Brines

Master Consulting Rosarian

Special to the Village News

The recent fires in the area have added ash to the dust in the air which will be deposited on the leaves of all plants in our gardens. The weather has moderated slightly and along with the change comes cooler nights with more moisture collecting on these leaves. This moisture with the daily accumulation of small dust particles will provide a great environment for mildew, rust and black spot on the roses.

Black spot is the most important disease of roses and one of the most common diseases found everywhere roses are grown. The disease does not kill the plant outright, but over time, the loss of leaves can weaken the plant making it more susceptible to other stresses and to winter damage. It first develops on upper leaf surfaces, later adjacent areas turn yellow and leaves drop prematurely...usually beginning at the bottom of the plant progressing upward.

Look-alikes: Spot anthracnose (shot-hole disease) is not a major problem unless it is very hot (too hot for black spot). Spots caused by black spot are fuzzy around the edges, then turn yellow and brown. Spots caused by anthracnose are smooth edged and the centers turn grey and drop out. Treatment is the same, but if a pesticide is used, it must be labeled for black spot or anthracnose, whichever disease you are treating.

Roses benefit from a good rinsing to remove accumulated dust: be sure to keep moisture off the blossoms to prevent yet another fungal disease Botrytis. which will appear as rot of blossoms and will usually prevent them from opening.

If you completed the light mid-season pruning in September/October as suggested in an earlier article, you pruned out dead, crossing canes, and thinned the middle of the plant. This will improve air circulation through the bush and reduce possible fungal diseases. This mid-season pruning and fertilizing encourages a new blooming cycle.

Cutting some of the early blooms now (and taking inside for bouquets) can help ensure having blooms around Thanksgiving. If you stagger your bloom cutting, you might have some for your December holiday table. That might is the big unknown, the main factor being the temperature (again). The average first frost date in our area is about Nov. 17.

You may make a final application of fertilizer for the year before mid-November. Unless you plan to exhibit I do not recommend fertilizing after mid-October. If you do this, use a fertilizer lower in nitrogen (N) and higher in phosphate (P) and potassium (K); that is, if your fertilizer has an N-P-K number on it, the first digit will be lower than the other two. If it lacks an N-P-K, read the ingredients and/or ask your professional nursery person for guidance.

To explain: nitrogen encourages foliage growth-something we want to discourage as the plants go into their winter dormancy; phosphate helps build root structure and resistance to stressful conditions (e.g., cold at this time of year); potassium is a helper of phosphate and aids in bloom quality. If you use an organic fertilizer it will be readily available when the soil warms, adding to the nutrients needed for that spring growth spurt.

Remember to check your garden daily for any changes. Be sure to keep them hydrated for best results. The cooler temperatures can be misleading. Roses still need to be watered, perhaps not as often.

Don't apply fertilizer after mid-November because it will only encourage tender growth that could be damaged by frost and will forestall your roses going into dormancy as the soil and general environment cool, daylight shortens, etc.

Some people think Southern California lacks distinct seasons, but we do have seasons: They are only discerned by those with a more sophisticated palette! So get out of the house and enjoy the subtle delights of the air, sun, and the rich aroma of our magically misty fall.

When you have a moment to spare, or feel the need to get away, or when the day cools down, take your favorite healthy beverage, a picnic basket, and visit Rose Haven Heritage Garden, 30592 Jedediah Smith Road, Temecula (cross street is Cabrillo Avenue). The early morning and late afternoon sunlight across the pass is magical this time of year – it even makes the freeway seem a little bit romantic! Other venues this time of year available for your interest check out http:pswdroses.org/calendat.html

Oh, one last thing – something to do when it gets just a bit too nippy out there: Start perusing rose catalogs (printed and online) for that next "gotta have" rose variety. (Come on-you deserve it! You work hard to have lovely roses, so let yourself go!) And we expect to see you enter that perfect bloom in the next rose show in April 2018!

Also, this time of year many nurseries and garden stores are liquidating their remaining inventory of potted roses – and you're in luck because November is an ideal time to purchase and plant! Nurseries will have their winter shipments first of December. Make your list of new roses and go shopping, if you plan to replace an old tired plant prepare the area now for easier planting later.