Many years ago, a friend of my grandmothers gave me some advice concerning the planting of rose bushes. Her advice concluded with a simple post-script, and don't forget to put a banana peel and a used tea-bag in the hole before you place the bush!" The banana peel was obviously organic material high in potassium, but the tea-bag?
Roses are heavy feeders and, with a few exceptions, will use almost as much fertilizer as you can give them. That's not to say that you should use huge doses, but smaller doses more often. As a rose show exhibitor I come across many rosarians who fertilize almost every day! The average gardener doesn't have the time to do this of course, so once a week becomes a great way to plan your rose bush feeding, using a mix of organic and chemical.
Most rosarians, when pressed, will own up to using their own special organic mix, which they consider to be their own special secret". The mix that is going to produce the biggest, healthiest blooms you would ever see! Well, whatever fertilizer mix you plan on using, it should contain the two magic" ingredients the rose growers in the know" are using. If you want good healthy bushes and an armful of glowing blooms, then you need to include these two ingredients in your fertilizing program.
The first is finely ground alfalfa. Rose exhibitors claim this to be the secret to greener foliage and larger flowers, and it's cheap! Alfalfa, as it disintegrates, produces an alcohol called triacontanol to which roses have a very positive response. A drink of this in early spring and it's like a kick in the pants", a wake up call to jump into action. Basal breaks are formed from the bud union and these produce the new canes. New canes mean new growth, increased vigor and a strong new bush. The alfalfa should be sugar free, not the sort you would feed rabbits for example, and finely ground, for it to act quickly. Two large cupfuls around each bush twice a year will do the trick, with the first one put down in early spring. Two tablespoonfuls would be enough for a container grown rose.
The second is Kelp, either in liquid form or granular. Kelp is an excellent source of many trace elements and rosarians will swear it has magical growth properties. It is made from the flat, rubbery looking seaweed that tangles boat motors, but free from salt and applied to our rose beds once a year in the spring, it becomes one of the miracle, organic rose bush stimulants. It is high in potassium and provides an abundant supply of growth enzymes, hormones and minerals. (About 60!) It strengthens stem cell walls so that your roses don't give up water so easily and get stressed during times of drought and are much hardier in colder climes. Kelp also feeds the micro-organisms in the soil, stimulating the soil bacteria which will allow the other organic soil additives to thrive. A very small handful per bush in early spring is all you need of this magic" stimulant.
Don't forget that all fertilizers require biological activity and moisture to release the nutrients: mix your magic ingredients into the dirt and water deeply. Don't worry, they are also self-regulating, releasing nutrients faster in the warm weather and slowing down in the cold: truly magic!
To quote my Grandmothers friend again, manure by the shovel and organics by the spoonful!" .....and please do not forget the banana peel and the tea bag.
