indicates low calcium, very high magnesium, and high potassium levels.
Dandelions indicate very low levels of calcium, and very
high levels of chlorine and potassium. Hop Clover and
Oxalis indicate very low levels of calcium and high levels of
magnesium. Prostrate Spurge indicates low calcium levels
and very high levels of chlorine, magnesium, potassium, and sodium.
Purslane and Mustard indicate an abundance of
phosphorus. Red Clover indicates an excess of potassium.
Redroot Pigweed indicates an abundance of nitrogen.
White Clover indicates very high levels in chlorine, magnesium,
and sodium. Wild Garlic indicates very low calcium and
bacterial count, and very high levels of chlorine, magnesium,
potassium, and sodium. Yarrow (Achillea millefolium)
indicates low potassium.
Soil can be depleted of a needed mineral or have an excessive amount
of a mineral and need to become more balanced, eliminating many
growing problems. Calcium doesnít move freely within the
plant, so the first symptoms of low calcium will appear in new growth.
Chlorosis begins first at the leaf edges and then moves inward.
Terminal buds become distorted. Young leaves will first turn
yellow, then brown. Low calcium levels cause tomatoes to develop
blossom-end rot and lettuce tip-burn. Low calcium is found in
acidic soils, sandy soils, soils that contain excessive levels of
magnesium or potassium. Temporary problems may be due to drought
or excessive moisture. Eggshells or oyster shells will
strengthen plants in low calcium areas.
Low copper levels will cause young leaves to become chlorite in
a strange way. Leaf center yellows while the veins and leaf
margins remain green for a while. Shoot tips die, terminal
leaves become brown or leaves may fail to develop. Common in
muck or peat soils, soils with too much lime, nitrogen, phosphate,
phosphorus, or zinc.
Low-iron chlorosis begins at the top of the plants and works
itís way down. Shoots may die back and the fruit become
discolored. Alkaline soils or soils with excess aluminum or
phosphorus can cause low iron levels. Iron is important in
photosynthesis and is a catalyst in plant respiration and iron
moves freely within plants, so a magnesium deficiency will start in
the lower leaves, discoloring the veins. First they turn yellow,
then orange, and finally brown. Leaves will feel brittle, thin,
and sometimes cup upward. Magnesium deficiency is found in wet,
acidic, or sandy soils, also in soils with high concentrations of
calcium, fertilizers, and potash. Magnesium is vital for
photosynthesis, facilitates the use of nitrogen, phosphorus, and
sulfur. It cleanses the plant of toxins that happen as a
by-product of its own metabolism, and itís needed in the formation of
Manganese deficiency may be hard to diagnose because itís
similar to iron deficiency. Chlorosis is most severe at the top
of the plant, with yellowing of the leaves first appearing near the
leaf margins and developing into a V-shaped pattern. Leaves will
then develop tan or gray spots. These spots are the major
difference between manganese and iron deficiency. Manganese
deficiency most often occurs in alkaline soils high in humus or soils
with a pH of 6 or more. Manganese is a catalyst in the process
of plant nutrition and encourages the growth and maturation of plants.
Nitrogen deficiency will cause plants to turn pale green, then
yellow. It begins at the tip of leaves at the bottom of plants,
especially older leaves, and works its way in the direction of the
main stem. Yellowing gradually spreads up the plant to the top.
Found in very sandy soils or soils low in organic material, also
excessively wet or leached soil. Nitrogen regulates vital
chemical reactions, needed in stem and leaf growth and induces rapid
In the early stages of phosphorus deficiency the plants look almost
too healthy. Growth is normal but undersized. Plants
become dark green frequently changing to purple, especially the
undersides of leaves. Sometimes stems also take on this color.
Leaves then yellow in the final stages. The plant has poor
flowering and fruiting habits. Most common in cold, wet or very
acidic (below pH5) soils and very alkaline soils (above pH 7.3).
Phosphorus in needed for root formation, flowering, fruiting
In potassium deficiency, the older leaves become mottled or spotted,
edges become dry and scorched. Dead spots begin to appear, the
stems are weak, root systems poor, and fruit ripens unevenly.
Potassium deficiency causes a reduction in disease resistance and
makes the plant less storable. It is more common in sandy or
acidic soils, also where there are excess calcium or magnesium levels
in the soil. Potassium is important for the formation of
flowers, fruit, leaves and growing tip. Potassium helps with
photosynthesis at low light level and in internal water regulation.
Potassium improves flavor, fruit, vegetable and flower color. It
also provides protection from insect damage, disease, and frost.
Sulfur deficiency closely resembles nitrogen deficiency. The
plants turn pale green, the effects show up first in young growth.
Leaves turn yellow but they don't dry out, and stems are weak.
Legumes are most affected. Sandy or very wet soils, and soils
containing excessive amounts of nitrogen are the most common soil
types with a potassium deficiency. Together with nitrogen it
makes protoplasm for plant cells.
A zinc deficiency can be similar to a nitrogen deficiency with
rolled leaf margins. Chlorosis shows up first in young leaves,
which are also reduced in size. Leaves are closely spaced,
forming rosettes, and may be deformed. There is poor nitrogen
formation in legumes. Soils that are sandy and acidic or
alkaline and rich in humus, or excessively high in phosphates,
nitrogen, calcium, or aluminum will most often be zinc deficient.
Zinc aids in the formation of growth hormones, protein synthesis, seed
and grain production, and plant maturation.
The observant farmer and gardener will notice subtle changes in the
weed populations as the soil changes. As the soil improves,
chickweed, chicory, common groundsel, common horehound, and lambs
quarter become the dominant weeds. However, if the daisy, wild
carrot, mugwort, common mullein, wild parsnip, wild radish, and
biennial wormwood become dominant, thatís a sign of the soilís low
fertility and can be corrected. The addition of well-balanced
compost, organic manures, and other fertilizers together with certain
tillage and drainage practices may be required to return the soil back
to a healthy, well balanced, and productive soil.
There will always be a battle between man and weed, but knowing that
weeds can be used not only as a soil indicator, but also the flower of
many weeds provide essential nectar and pollen, the foods needed by
beneficial insects to complete their life cycle. Most insect
pests would actually prefer to dine on weeds rather than your
deliberately planted crops, if given the choice, so weeds can be good
companion plants, and last, but not least, theyíre edible. I can
never defeat the weed, so I must live with the weed. Now I have
an excuse for not spending hours pulling out the weeds in the garden.
Now I can spend time wandering in my blended garden enjoying both
plants and weeds. They are rebels, just like me.