Common Nutrient Deficiencies in a Lasagna Gardens
OK, so we’ve built a supposedly fertile lasagna bed full of organic matter for your new plants. We’ve put in some healthy seedlings and some seeds, and you are watering it just right – not too much, not too little (stick your index finger all the way in to tell – read at the tip of your finger a couple inches in – sopping wet = too much, bone dry = too little). So what could go wrong?
Well, it’s a messy world out there! And we don’t have time and resources to do a full soil test before planting. Most commonly, there might be a tad too much ‘browns’ (carbon) compared to ‘greens’ (nitrogen) in our materials, and that can lead to slow growth and yellowing of older leaves – like in these cauliflower seedlings that are ready to get out of their seed starting mix and into a real garden with nitrogen! Heavy feeders like cauliflower might show this before other plants.
The solution? Add an organic nitrogen source. I recommend Fish fertilizer – just follow the directions on the back. A couple of times a week when you water should do it.
We don’t see this very often, but a garden I built at my house recently showed signs of serious phosphorus deficiency – red older leaves, stunted growth and red rims to leaves. Some areas of the bed were worse than others. Bone meal is a fix for this, but phosphorus is hard to mobilize in the soil and it may be a difficult situation to correct quickly! As you can see, some radish seedlings were particularly affected. I surmise that this is because mycorrizal fungi really help get scarce phosphorus to plants, but they do not pair with the mustard family (radishes, cabbages, kale, etc, etc)
In 80% or more of our gardens there is no issue at all and things grow like crazy – but if you do see any worrying symptoms, let us know and we’ll help you diagnose and correct things!