New growth on your roses in March is a reminder that it is time to purchase fertilizer. That sounds easy enough until you face the bewildering number of choices on the nursery shelves: granular or liquid, concentrate or ready-to-use, single- or multi-nutrient, OMRI organic-certified or chemical? What about those multipurpose products with insecticides? This simple purchase suddenly seems very complicated!
Start with the label. All fertilizers must specify the plant nutrients and the amount of each of the nutrients contained in the product. Our roses need nitrogen, phosphorus and potassium (N,P,K) which are the essential nutrients for plant growth, also known as primary or macronutrients. They also require smaller amounts of three secondary ingredients, calcium, magnesium and sulfur, and the micronutrients boron, chlorine, copper, iron, manganese, molybdenum, nickel and zinc. Not all ingredients are essential at every feeding. Amino Acid From Hair For Fertilizer
Nutrients in the soil get used up and depleted, so we add organic fertilizers such as blood meal, bone meal, cottonseed meal, alfalfa meal, seaweed, kelp meal, bat guano, feather meal and fish meal to our soil to provide our plants with their nutritional needs. Organics release lower concentrations of nutrients to the plant over a long period of time. Good brands include Bio-Start 3-4-3, Ada Perry’s Magic Formula 2.5-2.5-1, Dr. Earth 5-7-2 and E.B. Stone 5-6-3.
In mid-February or March and then again in July, lightly scratch these granules into the soil around each of your roses following directions on the product label for the amount to use. Top the granules with a layer of compost and cover this with 3 inches of organic mulch. I like to use Lifelike 3/8-inch Screened Compost from A-1 Soils in the Miramar area as my mulch. It improves my soil as it breaks down, and its small particles make it easy to pick up fallen petals and leaves. The company’s phone number is (858) 271-0203. Bagged organic mulch can also be purchased at garden centers.
Starting in mid- to late March, I use a soluble fertilizer that gives my roses a quickly assimilated boost. I use GrowMore’s SeaGrow Seaweed Plant Food 16-16-16 for the first feeding; it’s a blended product of all essential nutrients in an organic and chemical formulation. Two to three weeks later, I alternate with a completely organic product such as Neptune’s Harvest 2-3-1 or a hydrolyzed fish fertilizer 2-4-1. Continue feeding every two to three weeks until stopping fertilization in mid-October.
Organics improve the soil in addition to providing nutrients for the plants and are less likely to burn our plants. Chemically based fertilizers are convenient to use, work fast and are less inexpensive but they are not good for our soil and should not be used exclusively.
Stay away from fertilizers that include broad-spectrum insecticides as they kill not only insect pests but they also wipe out beneficial insects and beneficial soil fungi.
I used to dissolve my soluble fertilizers and use the labor-intensive method of carrying a bucket of fertilizer to each plant in my garden. I recently took the advice of rosarians in the San Diego Rose Society and started using a submersible pump or “sump pump.” It saves time and requires less effort making it a definite win-win. I bought a 1/6 horsepower Flotec brand. (If I had known I would like this method so much, I would have bought the quicker 1/4 HP model.)
Here’s the method: Fill a 30-gallon trash can with water and dilute the soluble fertilizer according to the directions. Stir well to dissolve. Your trash can should be on a caster with wheels so you can move it around your yard. Plug an extension cord into an electrical outlet. You will need two hoses: one hose to fill up your trash can and a second 3/4-inch hose fitted with a water wand that has a shower setting. The second hose, which needs to be long enough to reach your roses, attaches to the sump pump and will supply the fertilizer. Submerge the sump pump into the trash can, plug its cord into the extension cord and you can dispense the fertilizer. (Remember that you are dealing with electricity and water, so dry your hands each time you connect and disconnect your sump pump to the electrical cord, wear disposable or rubber gloves and make sure all electrical connections are dry.)
Before you start fertilizing your roses, do a test-run into a 1-gallon bucket. Count how many seconds it takes to fill up the bucket. My sump pump takes 12 seconds to dispense 1 gallon so I count between 5 and 12 seconds depending on the size of the rose I am fertilizing. When you are finished fertilizing all your roses, rinse the sump pump out with clean water.
Whichever fertilizer you choose, be sure to follow the label directions and water your plants before and after fertilizing.
Perwich is a member of the San Diego Rose Society, a Consulting Rosarian and a Master Gardener with UC Cooperative Extension.
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