Plant nutrients and their function

Plants speak to us through their leaves, look at their leaves carefully to see what they need. Use the diagrams below.

Major elements
Is for plant foliage, it is essential for the photosynthesis, the formation of amino acids, cell division and vital for plant growth.

Is for a plants root system but is also responsible for the quality of fruit and flowers. It increases plants hardiness, water absorption capabilities, growth of root system and is vital to seed formation.

Is for fruits and flowers but also increases resistance to pest and disease, increases plant hardiness, increases water efficiency and photosynthesis.

Minor elements
is needed for Continuous cell division and formation ,nitrogen metabolism, reducing plant respiration, helps deliver nutrients for fruit production and increases microbial activity.

Is needed for chlorophyll production and uptake of phosphorus and many plant enzymes and increases iron utilization in plants.

Is needed for chlorophyll formation, enzyme development, amino acids, seed production and the formation of nodules on legumes.

Micro elements
Is needed for germination, seed and cell wall formation, sugar translocation and it also assist in plant growth.

Is needed for photosynthesis, chlorophyll production, plant reproduction and other functional processes. It enhances flowers colour and fruit colour by increasing sugar levels.

Is needed as it increases Phosporus and calcium avaliablity to plants and chlorophyll synthesis.

Is needed for cell division, growth, and chlorophyll formation and the plants ability to carry oxygen.

Is needed to convert inorganic phosphate into organic phosphate and it helps to form the nitrogen fixing nodules on legumes such as peas.

Is needed for starch, seed and carbohydrate formation, chlorophyll production and it helps the plants growth and enzyme system.



Nutrient deficiencies in plants

For healthy plant growth a number of essential nutrients must be present in the soil. They need the major elements in large quantities such as Nitrogen, Potassium and Phosphorus and also minor or trace elements such as iron and Molybdenum.
Signs of nutrient deficiencies can be shown on the leaves. It’s sometimes harder to tell if there is more than one but this is a basic guide.

  • Older leaves with uniform yellowing often with reddish tints; premature maturity; growth retard; excessive leaf loss.


  • Stunted growth; blue-green or bronze timings on older leaves.


  • Leaf margins scorched; some spotting surrounded by pale zones on leaves.


  • Patchy yellowing on older leaves with dark green triangular pattern at base of leaf; excessive leaf loss.


  • Distorted stems; curling and mottling of older leaves.


  • Yellowish or light green areas between veins on both older and younger leaves.


  • Yellowing of younger leaves with veins remaining green; reduction in leaf size and early leaf fall. Iron becomes insoluble as the soil pH goes above 6.5 and less avaliable to plants.


  • Reduced leaf size; twisted foliage; creamy-white to yellowish blotches on young leaves.


  • Tip curling; blackening and early shedding of young leaves.


  • Yellowing leaf margins; dimpled apples; hollow stems in cauliflower; distorted leaves on beetroot; fruit drop on citrus.


  • Twisted and curling foliage; tips of young leaves wilt and die; leaves darken to a blue-green colour.


  • Yellowing on young leaves; reduction in size and failure to mature.
    Soil pH
    A soil with the pH of 7 is neutral, below 7 is a acid pH and above 7 is a alkaline pH. To raise the pH add lime and to lower the pH use horticultural sulphur.
    High amounts of other elements such as calcium, zinc, manganese, phosphorus, or copper in the soil can make iron unavailable to plants especialy Australian natives and plants in the Proteacea family. A shortage of potassium in the plant will also reduce iron availability.



Below is a Gardenia with a nitrogen deficiency caused when fresh mulch was used around the plant and the mulch used the nitrogen in the soil to beak down. This is known as nitrogen draw down. It is always good to apply blood and bone to the soil before mulching to avoid nitrogen deficiencies in plants.



What is seasol

Seasol or seaweed concentrate is not a fertiliser, it doesn’t feed your plants. It contains little or no NPK. Compare it too providing clothes and a warm home for your children but not actually feeding them, they wouldn’t be very happy. Seasol or seaweed extract is made from two species of seaweed – Bull Kelp (Durvillaea potatorum) and Knotted Kelp (Ascophyllum nodosum). Seaweed concentrate is a complete garden health treatment that contains plant nutrients, trace elements, alginic acid and other bioactive compounds. Seaweed promotes healthy roots, encourages beneficial soil micro-organisms and helps plants cope with stresses such as during transplanting, frost, heat, drought, pest and disease. It can also help with flowering and fruiting provided the plant has access to nutrition such as nitrogen, potassium and phosphorus.



The right pH for growing vegetables

If you would like to grow your own fresh vegetables in your backyard there are a few ways to make your vegetable garden a success. First you need to select an area that gets at least 6 hours sunlight a day vegetables need lots of sunlight to grow. Once you have selected an area you can use a planter box or a raised garden bed, this is easier on your back when working in the garden and allows for better drainage, these will then need to be filled with a good quality garden mix soil. A vegetable garden that is in the existing ground will need soil improvements such as adding manures and blood and bone and then it will need to be broken up and turned over to loosen up the soil for root growth. When the seedlings are planted they should be watered in with a seaweed extract and mulched with sugar cane or pea-straw.  In between crops you can plant a green manure such as peas and when they reach about 40cm dig them into the soil. Peas are a legume and they fix nitrogen out of the atmosphere and onto there roots so when you dig them in they add nitrogen to the soil.  Vegetables need to be fertilized often during there growing season anywhere between every  2 and 4 weeks  depending on the fertilizer you use. The pH for growing vegetables is very important as  the plants can only take up nutrients if the soil is at there preferred pH so I have put together a list of vegetables and their preferred pH   below.

Artichoke 5.6-6.6
asparagus 6.0-7.0
beans 6.0-7.0
broccoli 6.0-7.0
cabbage 5.6-6.6
carrot 5.0-6.0
cauliflower 6.0-7.0
chard 6.0-7.0
chives 5.0-6.0
dill 5.0-6.0
garlic 5.0-6.0
leek 5.0-6.0
mint 6.0-7.0
okra 6.0-8.0
parsley 6.0-8.0
peas 5.6-6.6
peppers 6.0-8.0
pumkin 5.0-7.0
raspberry 5.0-7.0
spinich 5.0-7.0
Sweet corn 6.0-7.0
Swiss chard 6.0-7.0
yam 6.0-8.0
beet 5.6-6.6
Brussels sprouts 6.0-7.0
celery 6.0-7.0
Chilly pepper 5.0-6.0
cucumber 5.0-6.0
eggplant 5.0-6.0
kiwi 5.0-7.0
lettuce 6.0-7.0
mushroom 7.0-8.0
onion 5.0-7.0
parsnip 5.0-7.0
potatoes 5.8-6.5
radish 6.0-7.0
rhubarb 5.0-7.0
shallots 6.0-7.0
squash 6.0-7.0
Sweet potatoe 5.0-7.0
tomatoes 5.0-6.0
zucchini 6.0-7.0