Roses have been around quite a while, first debuting in fossil records dating back 60-70 million years. Even Confucius loved and wrote about roses. Of more historical inerest, Alexander the Great is credited with introducing cultivated roses to the rest of Europe.
In Napa County, we love our Fuller Park roses as well. We did our heavy winter rose pruning in January, anticipating the reward of the explosion of blooms in May and June.
Due to Napa's fairly warm agricultural zone 9B, Sunset zone 14, it is sometimes a little sad to prune back roses, as they could grow year around if we let them. We cut our bushes back to 18”- 30” even though they were still blooming! Maybe like pulling off a band aid, it hurts for a moment, but it is the right thing to do. The rose bush will grow stronger with the right treatment.
The good news is that we're coming into March, which means the canes and stems that were pruned in January are now showing buds that are starting to swell, the leaves are starting to appear and it is looking like winter is coming to a close. However, this is not the time to sit and wait for great things to happen. We have to work like crazy now for great results in June.
The Master Gardener's Rose Cycle chart (https://napamg.ucanr.edu/files/254549.pdf)indicates that we should have finished all our pruning by January. We have cleaned up all fallen leaves and debris from the pruning and placed in our compost cans for composting at the local facility (https://naparecycling.com/residents/napa-recycling-facility/). That is critical as fungus that leads to black spot and mildew is harbored in the cuttings. Keeping the area clean gives roses a great start.
We add mulch to the soil to help keep moisture in the soil, but do not pack mulch against the stems as that could promote rot and stifle air circulation at the base. In addition, a slow release rose fertilizer can be added now to promote spring growth. Fertilizer has 3 basic elements indicated by the Letters: N-P-K. They stand for Nitrogen (N) to aid the growth of green leaves and stems, Phosphorus (P) that stimulates the root system, growth and blossoms, and Potassium (K) that fosters resistance to diseases and stress.
As rose blooms are cyclical throughout the year, the application of fertilizer in several light feedings throughout the season is recommended. I do it after winter pruning, again around Mother's Day and finally around Labor Day.
Spring growth is heavily in favor of growing stems and leaves, so in Winter a fertilizer with a ratio of 3-1-3 (e.g.12-4-12) could be a good choice. Just don't overdo the recommended yearly amount.
Just to make your head spin a little, there are also secondary and micronutrients that are needed for plants. They include: calcium (Ca), magnesium (Mg), sulfur (S) as secondary nutrients. Iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) are considered micronutrients.
When choosing a fertilizer supplement, it would be a plus to have beneficial bacteria and micronutrients available in the mix. Having a dose of beneficial bacteria improves the health and function of the roots. Different fertilizer producers may favor one or two types of bacteria in their mix. Talk to your local plant nursery provider for what may be best for your soil.
In March, we should fertilize with organic products, to give the bushes the extra nutrients that will give them a bigger boost for June. This is also the time to see if spraying is needed. A long winter with frequent rains can stimulate the fungus that we want to avoid. The spray will control pests, eggs, and larvae that are harbored in the soil. If you do spray, do so right after the pruning. Otherwise, do so when there is a calm and dry day and no rain anticipated for a couple of days. Make sure you spray all the pruned canes, stems and the soil under the bush. Do not wait so long that the new foliage breaks out. Always remember to follow the instruction on the spray container. The most common spray is a dormant oil also called horticultural oil. Some are easy to use as they are combination of copper-based fungicides or a sulfur product along with disease preventing neem oil.
Do your due diligence for your roses now, you will be greatly rewarded later with fantastic roses in June, if not sooner. Master Gardeners tend to the Fuller Park roses twice a month (Usually the first Thursday and 3rd Sunday of the month.) If you would like to talk roses with us, come on by. We'd be happy to chat and show you what we are up to ANYTIME we are there!
Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143. Volunteers will get back to you after they research answers to your questions.
Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.
Photo credits: Bob Niklewicz
