There are many suitable formulas suitable for orchids. Orchid Focus Grow and Orchid Focus Bloom are recommended for those with a small collection, the DynaGrow range is suitable for larger collections as it is highly concentrated.
Alternatively you might like to “mix your own” using a formula suggested by Mike Armstrong of Mikandra Orchids:
Many years ago, I became frustrated with the lack of information on what to feed orchids. After finding the information I wanted, which came from tests on orchids over a long period, I adopted the following regime. In the tests, it was found that orchids need very little Phosphate (Phosphate is the middle element in the N P K on the packet of feed)! Excess Phosphate locks off the nutrients to the plant in the compost and accelerates compost break down.It must be stressed at this stage that the use of a conductivity meter is essential. The regime run on a monthly cycle is as follows:
• Two weeks on 1-0-3 (13-0-45) - Chempak Specialist Soluble No. 10
• One Week on 1-1-3 (12-12-35) - Chempak Formula 5
• One week clear water
The mix should be as follows:
•10 ml feed
• 2.5 ml magnesium sulphate (AKA Epsom Salts)
• 2.5 ml Calcium Nitrate
All should be mixed together using a conductivity meter to control the strength. I use a set of plastic kitchen measuring spoons. I always transfer some of the feed to small plastic containers and work from them, then if you have a problem only a small amount of feed is ruined.
All the above feeds can be obtained from Chempak’s mail order division Garden Direct,(some also from Garden Direct Online) Dept MO, Hillgrove Business Park, Nazeing Road, Nazeing Essex EN9 2BB Tel:01992 890550 or as individually packed chemicals at most garden centres (see details below). The strengths of the feed controlled by a conductivity meter is as follows:
• January/February 250-300 µS (175-210 PPM)
• March/April 350-400 µS (245-280 PPM)
• May/June 400-450 µS (280-320 PPM)
• July/August/September 500-600 µS (350-420 PPM)
• October 400-450 µS (280-320 PPM)
• November/December 300-350 µS (210-245 PPM)
N.B. µS = microsiemens.PPM = parts per million.