Local weather and soil remain warm so it probably seems like spring to your roses, which I’m betting have continued their growing cycle even though it is March.
In a new rose garden, or with newly pruned roses that haven’t sprouted new growth, remove all debris, apply lime sulfur dormant spray according to the package direction, and then thoroughly wet all canes and the surrounding soil. For roses that have sprouted, be more careful in your application and be sure to follow the “growing season instructions” on the label.
Given that your roses are about as bare as they’re going to be for the rest of the year, take time now to inspect and make any necessary repairs to the irrigation system. Drip systems are the most efficient and they avoid problems of above-ground sprayer and sprinklers which waste water (especially important during our serious drought) and can foster molds, mildews and rust. Make sure your irrigation system is in good working order; for example, make sure all the emitters are delivering the expected amount of water and that there are no leaks.
If you completed your rose pruning last month you are probably seeing tender, new, red-coppery growth – a pleasing result for rose aficionados. Now would be the time to sprinkle ½ cup to 1 cup of Epson Salts widely around the base of each plant. (Use half as much for minis and mini-floras.)
There is some indication that this helps in producing new cane growth known as “basal breaks.” If your feeding program is organic, you can apply fertilizer immediately after pruning. If you use inorganic fertilizers, wait until this new growth is 2-3 inches long. I suggest the initial feeding be higher in nitrogen to encourage new stem and leaf
When new growth is 4-6 inches long, apply a fertilizer higher in phosphate to give roots a boost at the start of the season. Another method used by some is to sprinkle superphosphate (available at home stores and nurseries) on the soil surface at a rate of 1 pound for every 10 square feet. Lightly water it into the
Top your rose bed with a 2” to 4” layer of organic composted mulch. If you’ve read this column for more than a month or so, you know that I’m a big believer in composted mulch! It’s best if it covers the entire rose bed. It will help supply nutrients for beneficial soil organisms that transport these nutrients into the plant root zone. It will also insulate the upper 8” to 12” where most rose roots feed, keeping it cooler in summer and warmer in winter. Mulch also helps prevent water loss and evens out the soil moisture.
I am often asked how much water a rose needs. This is another of those “it depends.” It depends on a lot of factors: weather, the size of the plant, the composition of the soil, the cycle of growth, the variety of the plant, etc. Typical mature, full-size hybrid tea in Southern California soil requires about 6-9 gallons of water a week when the high temperatures are in the 70s. As temperatures rise into the 80s, the rose will require about 9 gallons of water per week. In the 90s, the rose will require about 12 gallons per week and even more. A miniature rose, depending on size, requires about one-third to one-half as much. These figures are rough and based on the amount of water needed to maintain the highest level of show quality; the rose will stay alive on considerably less.
For your regular feeding program, I recommend that you avoid products that describe themselves as “systemic.” These contain insecticide and/or fungicide (mold killer) that enter the plant through the leaves and roots, and circulate within it. I avoid such products for two reasons.
First, because much of the product ends up washing into the soil, you are laying waste to a wide range of soil organisms, including beneficial ones, thus making your soil less diverse and dynamic – this can only be bad in the long run for your plants. Secondly, because these poisons circulate within the plant, there’s a chance that they are implicated in the widespread collapse of honey bee populations.
Also, “bad” bugs will feed on the poisons and in turn poison the beneficial insects, birds, the praying mantis, and lady bugs that eat them. Because these predators are further up on the food chain, they concentrate the poisons and can be killed by them too. Finally, if you plan to use blossoms or petals for any household purpose (potpourri, recipes), be aware that these poisons are in all plant parts, also in the blooms and thus petals.
Also, I use and emphatically recommend organic types of fertilizer, as vs. inorganic or “chemical” ones, because organics are less concentrated (thus less likely to burn plant tissues) and their nutrients are released more slowly. This fosters better soil development, making for a richer, livelier, and more viable community of soil organisms that is able to break the elements into an easily absorbed form and releases them slowly to the plants. As your soil develops, you’ll be able to use less and less product and save money in the process.
Be sure to visit the Rose Haven Heritage Garden located at 30500 Jedediah Smith Rd. in Temecula. Also, visit www.TemeculaValleyRoseSociety.org regularly for more information and a schedule of events. Spread the joy of roses!