Plants will usually show the following signs of deficiencies of mineral nutrients. There may of course be other causes rather than a nutrient deficiency for some of these symptoms, like a lack of light, heat, water or water-logging, so check these before taking the steps explained below to rectify a deficiency of mineral nutrients.
The effect of a deficiency of mineral nutrients in your soil on plants;
Leaves are small and light green, lower leaves lighter than upper ones, not much leaf drop and weak stalks.
Dark-green foliage, lower leaves sometimes yellow between veins, purplish colour on leaves or petioles.
Potassium is important for a plant's ability to withstand extreme cold, hot temperatures, drought and pests.
Symptoms of potassium deficiency include yellowing of the lower leaves and in severe cases leaf-tip die-back. Lower leaves may be mottled with dead areas near tips and margins of leaves and yellowing at the margins continuing toward the centre of the leaves.
Calcium is essential in your garden soil, without calcium, plants can't grow. Plants need calcium for the growth of young roots and shoots. Calcium deficiency in soil is very rare. Over watering is the main cause of a deficiency (see Magnesium) and causes the tip of shoots and tips of young leaves to die and tips of leaves are hooked-shaped.
A shortage of Magnesium is often caused by too much watering or heavy rain washing the Magnesium deep into the soil, out of reach of most garden plant roots. (Calcium cannot be used by garden plants without Magnesium).
It's brought back up by deep rooting plants like trees, so it's a very good idea to spread fallen leaves back onto the soil instead of sending them off in your green bag. Magnesium deficiency is recognized by pale green leaves and blossom and fruit rot. The lower leaves are yellow between green veins, leaf margins may curl up or down or leaves might pucker and die in later stages.
light green upper leaves and leaf veins lighter than surrounding areas.
New upper leaves turn yellow between veins (large veins remain green) edges and tips of leaves may die.
New upper leaves have dead spots over surface and the leaf may appear netted because of small veins remaining green.
Tip of the shoot dies and stems and petioles are brittle.
Plants can also show some of the signs outlined above where the growing conditions are poor and the plants are unable to take up nutrients present in the soil. Very acid or alkaline conditions, dryness and water-logging can all make it difficult for plants to take up soil nutrients. However, if you are sure the problem is not caused by the growing conditions these remedial tips should help.
Actions to take to correct a deficiency of mineral nutrients in your soil.
The best remedy in the long-term, is mulching with organic matter like well rotted garden compost or manure provides a steady trickle of nitrogen to stabilise levels. In the short-term, sulphate of ammonia or poultry manure pellets will remedy the problem.
Correction involves increasing the levels of phosphorus in the soil with bone meal, rock phosphate and manure.
For soil severely deficient in potassium add rock potash. Rock potash contains 10.5 percent worth of potassium and is released slowly so you won't overdose your plants. Wood ash applied directly to the soil also adds potassium.
Calcium deficiency in the soil is very rare. Not watering evenly (to dry and then to wet) is the main cause of calcium deficiency. Adding horticulture lime will help, but I wouldn't spend to much time worrying about a lack of calcium unless your soil is extremely sandy. A soil test is the best way to find out if you have a problem. Calcium cannot be used by garden plants without Magnesium, work at getting magnesium right.
Regular sprinkling of dolomite or Epsom salts onto the soil helps. However, the best and most natural way of getting Magnesium back into the soil is spreading tree leaves over the garden. Deep rooting plants like trees bring Magnesium up from deep down in the ground and store it in the leaves, so it's a very good idea to spread fallen leaves back onto the soil instead of sending them off in your green bag.
Sulphur deficiency is more common in plants grown in sandy soils that are low in organic matter and in water-logged areas. Remedy by adding organic matter from your compost heap and in very wet areas by installing garden drainage.
Rarely is an iron deficiency in plants caused by an actual lack of iron in the soil. More likely a variety of soil conditions can limit how well a plant can get to the iron in the soil caused by Soil pH being too high. If soil has too much clay, is compacted or waterlogged. Or too much phosphorus in the soil.
When manganese deficiency due to high soil pH is confirmed. The only permanent and realistic solution is to replace plants susceptible to manganese deficiencies with plants better adapted to the pH. Decreasing the soil pH of these soils and maintaining a low pH level is extremely difficult, time-consuming and expensive.
Treat by applying borax mixed well with a large quantity of light sand to the soil before planting.
"Composting is a great way to recycle kitchen and garden waste, even easier than trying to work out which bin to put stuff in and means less rubbish going to landfill" And healthier soil in your garden.
Got the nutrients right? don't forget the gardening basics and some of these are;
Temperature. Plants grow best within a limited temperature range. Warm-season vegetables and most flowers grow best between 60° and 80° F. Vegetables such as lettuce and
spinach between 50° and 70° F.
Light. Most vegetable plants and all fruits and flowers require large amounts of sunlight, some will tolerate some shade. No plants will grow in darkness.
Greenhouse plants will not do as well during the winter as in the summer. Shorter days and cloudy weather reduce the light intensity and limit production. Most will do better if grown from January to June or from July to December than if they are started in the autumn and grown through the winter months.
Water. Obvious you say, but during the hot summer months container grown plants need a lot more than those growing in the garden.
Oxygen. Plants require oxygen for respiration to carry out their functions of water and nutrient uptake. In soil adequate oxygen is usually available, but in water-logged or permanently wet soil plants find it harder to get at.