Here’s a copy of my Spring and Fall Rose Tonic. It is a modification of a recipe passed to me by a very wise and 83-years young rosarian. It assumes your soil pH ranges from 6.5 to 7.5, clay-based and/or rich in calcium.
- 8 parts alfalfa meal
- 2 parts cottonseed meal (arsenic-free)
- 2 parts rock phosphate (or colloidal phosphate; but not super phosphate)
- 2 parts bone meal
- 1 part blood meal
- 1 part Epsom salts (magnesium sulfate)
Thoroughly combine ingredients and apply 1 cup (.24 l) of the mixture for each foot (30 cm) of shrub height. Lightly scratch the mixture into the soil using caution not to harm the roots. Water in thoroughly.
This mixture is good in the spring and the fall, and can be applied as a ‘tonic’ to all blooming perennials, roses, azaleas and fruit-producing trees and plants.
- If soil pH is above 7.5 (and it shouldn’t be), reduce the Epsom salts by half to reduce the possibility of applying too much magnesium.
- For new plantings, add 1 part Greensand (0-1-5) to the Fall Tonic
- The NPK of the constituents varies by manufacturer; however, on average these proportions will create a 50-110-20 (or approx. 2-4-1 NPK ratio) slow-release, environment-safe fertilizer. It will not “burn” the foliage or contaminate the soil.
- Blood and bone meals may attract dogs and cats. If this is a problem, repel with pepper spray around the watering well.
- Feather meal may be substituted for alfalfa meal, but the quantities should be cut in half. Feather meal is also quicker to decompose and will not provide sustained nitrogen release beyond about 21 days. Furthermore, alfalfa has micro-nutrients not found in feather meal.
- Alfalfa meal is quite dusty; a dust mask should be worn when mixing the ingredients.
I apply this tonic immediately after spring and fall pruning (here, late Feb and late Aug). It is so effective, supplemental fertilization’s are not required but once-a-month in the spring – until I let the roses rest during summer’s heat. For supplemental fertilization’s, I use a blend of fish emulsion, kelp liquid concentrate, and un-sulfured molasses @ 2 Tbsp, 1 Tbsp, and 1 Tbsp (30ml, 15ml, 15ml) respectively per gallon of water and pour this around the watering well of each rose.
It is best, if you have a lot of roses, to purchase the ingredients in bulk from the farm/ranch or feed store vis-à-vis the nursery or mail order. For example, alfalfa meal at the feed store costs about $8 for 40 lbs. At the nursery, it costs $7 for 4 lbs. – and it’s the same stuff, just packaged with a prettier label. Use caution when purchasing from a feed store, however, to ensure the alfalfa does not contain salt, as this will be detrimental to your soil. (Try a taste test.)
And if you grow roses in pots or sell them commercially, sprinkle 1 or 2 cups of mixture on the top of the pot. When you water the plants, the fertilizer acts like a timed-release mixture that can cost much, much more.
It should also be noted that some rosarians who live in cold climates report they have reduced aphid and thrips infestations if they withhold fertilizing until after the first flush of the spring, thus letting the rose generate growth and blooms from the stored energy in the roots (e.g., like bulb perennials). This would not work for us who live in warmer climates because the first flush may not end until May or June when our temperatures quite regularly get above 95°F(35°C) and our roses like to rest during summer’s heat.
I hope that helps a little. But remember, this is what works for me and my garden.