Ok, so I've searched and I just can't find any information detailing how old my baby should be before giving it nutes. My oldest plant is 2 weeks and 1 day old. Is this too young?
You should wait and let the plant tell you when it needs feeding. In any case after about 2-3 weeks of being in the seedling soil, you should be thinking about potting it up to the next pot size and in doing giving it another fresh set of nutrients to start feeding from, meaning you don't have to feed it any nutrients.
Also, I'm not 100% sure how to mix this as a water solution for soil? Here is the label on the Ionic Grow:
The Ionics range are low priced but reasonable quality at the level they're positioned at and they can be used for soil. Be aware though, they come in different hard and soft water formulations.
I know that I should be starting with 1/4 strength, so does that mean I should use just under 2ml of Ionic grow for every litre of water I use?
The reason people say start at 1/4 strength is because they 'don't reeally know' what level of nutrient strength to start feeding at. People need to work this out for themselves, but few actually have the knowledge or equipment to be able to do so. You can't go by the recommended doseages because they're frequently wrong for Canna plants, remember, the manufacturers guidelines are there for a whole spectrum of plants - not just one type. Add in different circumstances and strains, different environmental conditions and it's almost impossible to give a general feeding recommendation for all plant types and situations. That's why you have to work it out yourself.
Ionics give a guide to the EC (Electrical Conductivity) of that bottle for soil - 15cf (conductivity factor). Which is 1.5 EC or 1050 ppm (parts per million) on the Truncheon scale. Assuming the ph is correct and there's no salt buildup, I'd say 1.5 EC was about twice as much as the maximum doesage you should be feeding. Depending on the EC of your tapwater (because that also contains dissolved salts) you should be feeding at about 0.7, 0.8 EC. So If your tapwater has 0.2 EC, you can add up to 0.6 EC of nutrients.
To measure EC, you'll need to invest in an EC meter or a Truncheon. For the moment, you'll be okay with a 1/4-1/2 recommended doseage feed.
Lastly, how often should I be feeding my plants this?
At about 0.6 - 0.8 EC you should be feeding at about once every other watering, but your frequency will depend on how much feed the plants need. A little but often is best for feeding, so small amounts of feed regularly are better assimilated than large doseages , where the plant simply cannot uptake all the nutrients and store them and excesses start to toxify and 'burn' the plant by an excess salt buildup.
