It sounds fine, so long as you keep up the water changes and get a true mated pair of Discus if you are only going to keep two. Bear in mind that Discus are big messy fish, so you might not need fertiliser for the plants.
An extract from a thing I wrote:
Discus are relatively big and messy fish, they are a schooling fish (like tetras they should be kept in small groups) but they are also territorial and hierachical. Provided you give them what they need they are pretty hardy.
Give them clean, soft water, and plenty of it. You need to do regular, large water changes - I personally change 70% per week. I think they benefit from having driftwood in the water - it softens the water and also releases certain acids etc. that seem to be important to long term health.
Give them companions - unless you have a true mated pair you should keep at least 5 Discus - you can successfully maintain smaller groups, but having 5 or more makes it easier because it spreads the inevitable battles around. 'Dither' fish such as cardinals can help make them feel less threatened - aggressive, fast moving and / or 'nippy' fish should be avoided.
Give them enough space to let individuals form small territories - I use a 'reverse' fish length stocking rule - at least one foot of tank length for every adult Discus. Again, you can stock more, but it makes long term success and happiness harder. They need open areas to swim - don't overplant your tank.
Give them a high quality varied diet - including frozen bloodworms and high quality granular and flake foods with some vegitable content, although protein levels need to be high. I've had good success with the JBL range of foods + frozen bloodworms twice per week. Clean up leftovers after half an hour unless you have Bristlenose Ancistrus or other fish that will consume it - don't leave excess food to rot.
Don't over-react to percieved symptoms - often Discus (like most other animals) will recover from small injuries and sickness without medication, provided you have met their basic needs.
Did I mention water changes?