How to keep rose bushes healthy and growing

As of this writing, El Niño has been fading and La Niña has been building, and to our surprise, aiming multiple “atmospheric rain rivers” right at California.

I'm beginning to think that normal climate may be the abnormal. In less than five months, rains have all but ended our five-year drought. Be prepared for a season of vigorous growth – both of roses and their diseases!

Daytime temperatures in February ranged in the 60s to 70s, and with the amount of rain we've had the roses have burst with growth – some even have buds. If you finished pruning in mid-February, I'm sure you're seeing a good flush of new leaves.

If you haven't bought new roses yet, you can still do so and might even find some great offers. Some online nurseries are still shipping to this area. Plants already in pots would be the best to buy as they will be far easier to transplant and will establish themselves quicker. Look for those with three to five major canes.

Be sure the ground around, under, and between bushes is clear of debris. Also, remove all old leaves that may be left on the bush. This cleanliness will help keep down disease.

If you didn't use a lime-sulphur dormant spray earlier, you can still do so. Read the label and use the recommended dilution for “growing season instructions,” especially if there is new growth. Be sure to saturate all canes and the soil surface of the entire bed.

Apply a minimum of 2” to 4” of organic composted mulch over the entire garden surface to insulate the upper 8” to 12” where most rose roots feed and to reduce evaporation and conserve water, while still providing sufficient moisture. It will also supply nutrients to and build the soil for your roses for the season.

Take time now to inspect and make any necessary repairs to your irrigation system. Drip systems are the most efficient and they avoid problems created by above-ground sprayers and sprinklers, which waste water and can foster molds (e.g., mildew and rust).

For best results and efficiency, be sure to time the irrigation so it is complete before the day gets hot (preferably by mid-morning, that is, 8 to 9 a.m.). If possible, avoid any over spray or misting of water being applied elsewhere in your garden that may hit your roses.

Avoid daytime watering to avoid creating excess ground moisture into night time. Too wet soil can lead to unhappy roots and/or fungal diseases. If you use overhead watering systems avoid doing so when there is any wind to avoid moisture collecting on leaves which could result is sun burn or add to conditions favorable for fugal diseases.

Now would be the time to sprinkle ½ cup to 1 cup of Epson salts widely around each rose bush (use half as much for minis and mini-floras). There is some indication that this helps stimulate new cane growths known as “basal breaks” at the bud union (the big part next to the ground where grafting was done).

When the new growth is 2” to 3” long, you can begin fertilizing. I suggest an initial feeding each year be higher in nitrogen (N) to encourage new stem and leaf growth.

In about two weeks, apply fertilizer that is higher in phosphate (P) and potassium (K) to give roots a boost at start of season. New information suggests that continued use of fertilizer higher in P and K will foster greater root development and lead to better growth and resistance for healthier plants.

I highly recommend organic type fertilizers as vs. inorganic or “chemical” ones. Organics foster better soil development, a richer, livelier, more viable community of soil organisms that break the elements into easily absorbed form and release them slowly. They will “build” soil structure into a healthy component and, when used regularly, will develop a soil rich in reserve energy, allowing you to use less product with the same results.

There are rose events coming up which you may find of interest. Pacific Southwest District Mini rose show convention is April 19-23 at the Los Angeles Arboretum and the San Diego Rose Society rose show is on April 29. Plan to attend one or both and experience seeing the blooms of your favorite roses or research possible new addition to your garden. Entry applications for garden show at the San Diego Fair are now being accepted at www.sdfair.com.