On 2/11/2015 8:32 AM, Hypatia Nachshon wrote:
On Monday, February 9, 2015 at 3:49:51 PM UTC-8, David E. Ross wrote:

My roses are already showing leaves, so I fed them yesterday. I gave
them a mix of ammonium, iron, and magnesium sulfates (listed in
declining amounts).

Tx, David. How is this different from commercial rose food from nursery?
I don't have one handy to compare formulae.

TIA


Commercial fertilizers often contain phosphorus, which is a waste of
money and a potential pollutant. The problem is that phosphorus --
which promotes flowering -- does not readily dissolve. Instead, it must
be placed where roots will find it. That is why I always place either
bone meal or super-phosphate in the bottom of planting holes when
planting something. Also, every 5-10 years or so, I take a piece of
steel rebar, poke holes about 1-2 feet deep in the root zone of my
roses, and then fill the holes with super-phosphate.

Furthermore, roses prefer an acid soil. That is why I use sulfates.
Most commercial fertilizers are relatively neutral.

Despite all that, I do use a commercial fertilizer. I feed my roses
monthly from the time new shoots appear after pruning until late
October. After the initial feeding with ammonium, iron, and magnesium
sulfates, I alternate between only ammonium sulfate (nitrogen) and a
commercial fertilizer that contains a systemic insecticide. The
instructions for the commercial fertilizer say to use it every 6 weeks,
but I only use it a full two months apart. I never see aphids, spider
mites, or bark borers.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary