PLANT HEALTH Plant Nutrition Deficiencies: Macro Nutrient Nitrogen The 'Plant health' segment was created for my radio show "Real World Gardener,' as a division of the 'Plant doctor' segment, because I felt that it’s important to focus on what can go wrong with plants that isn’t a pest or a disease. In the following audio podcasts, you will hear about what to look for in plants that have deficiencies of one of the macro nutrients: Nitrogen:Phosphorus:Potassium; in other words NPK or the macro nutrients. Gardeners can often see problems appearing first in the colour of the leaves, but this can also be followed closely by lack of vigour, stunted growth and general unthriftiness of the plant.   The key to diagnosing problems, however isn't just looking at the colour of the leaves but it's knowing your soil type and soil pH. Yes, I know, we do go on about soil pH but that often underlies the reason behind your plants' problems. The other underlying problem may be insufficient drainage which causes waterlogging of the soil.   That said, we  will assume that you soil pH is around 6.5 - 7 but your still seeing issues that are showing up in the leaves. So what next? Macro Nutrient Nitrogen Nitrogen is one of the three big nutrients or macro nutrients that plants need. Nitrogen is responsible for leaf growth and blossom formation.   First Symptoms: Oldest leaves start to appear pale first, yellowing at the leaf tips then eventually the whole leaf will turn yellow. Quick Fix: Soluble fertiliser high in nitrogen.  Results should appear in a few days. Long term fix: Blood  n' Bone and/or controlled release fertilisers.   Nitrogen on it’s own can be useful for quick greening of lawns and leafy plants like ferns in pots when the potting mix is depleted of any nutrients. Listen to the podcast: I'm talking with Kylie Last horticulturist and tafe teacher. If you have any questions you can email us [email protected] or write in to 2rrr, PO Box 644 Gladesville NSW 1675.