Healthy well-balanced organic soil goes a long way toward giving you great plants
but keeping the soil balanced to where plants get all of the various nutrients need
during all phases of growth very difficult. Plants go through various stages of
growth and the amount of various nutrients needed during these stages will vary widely.
The healthiest of soils, plant roots and soil biology cannot make the adjustments
necessary in a time frame needed to deliver everything the plant needs.
Foliar feeding can take up this slack. It is an effective way to get almost instant
results, it giving the plant what it needs when in needs it. This means healthy plants
that are even more resistant to insects and diseases.
Foliar feeding can work in two ways depending on what you use in your feeding program:
First, is used as a nutrient spray that passes into the leaves to provide nutrients
to the plant. It can be from 8 to 20 times more efficient than soil feeding if done
properly, and in many cases, you will see a change within hours.
Second, if you are including beneficial biology in your spray mixtures to help colonize
leaves it can help prevent disease and control many types of harmful insects.
Feeding leaves nutrients: Your spray will enter leaves through openings in the leaf
surface called the stomata. Stomata are a pore (or opening) in all above-ground parts
of plants including the petals of flowers, petioles, soft herbaceous stems and leaves.
Their main function is to allow gases such as carbon dioxide, water vapor and oxygen
to move rapidly into and out of the leaf. Stomata are formed by two guard cells that
regulate the opening and closing of the pore. Generally, many more stomata are on
the bottom of a leaf than on the top. Normally stomata open when light strikes the
leaf in the morning and close during the night. They will close during the day when
the amount of water coming up from the roots is insufficient to cover the water being
lost through the stomata. Because these openings do close up as the temperature increases
you need to spray in the early morning or late evening when temperatures are lower
and plants are most active.
Foliar spraying of plants at times of growth spurts where shortages of nutrients
can show up can do wonders. Other times when nutrient deficiencies can show up such
as zinc and iron which are difficult to get from roots in adequate quantities. In
times of plant stress such as extended dry periods when root feeding cannot keep
up. Foliar spraying is said to give plants a boost that will cause nutrient movement
from the roots into the leaves for processing.
Furnishing beneficial biology: Bacterial diseases on leaves are difficult to control
inthat they can spread rapidly if healthy leaf biology has been depleted. Chemical
pesticides and antibiotics have been used for control disease control but have proven
undependable and can be harmful to both you and the environment.
(a) healthy leaf surface colonized by beneficial organisms.
(b) leaf surface with active disease sites and few organisms
Leaf surfaces have a rich microbial population which helps protects the leaf, and
thus the plant, from infection, attacks by pathogenic organisms and they work with
plants to protect from weather related problems. When the colonies of beneficial
organisms present on the leaf surface are reduced by pesticides, other harmful chemicals
or from environmental damage it exposes leaf surface infestation of harmful insects
and other organisms.
When bacterial diseases get started they are difficult to control by chemical sprays
like copper and antibiotics. Both are undependable and may have harmful consequences
to the environment. Keeping normal levels of natural biology on the leaves can prevent
or minimize bacterial diseases. Interactions between plants and beneficial bacteria
can have a major effect on crop health and yield and soil quality. These microorganisms
can sensitize plant cell metabolism. When plants with beneficial organisms on their
leaves are exposed to stress the sensitized plants are able to respond rapidly and
efficiently. The mechanisms by which beneficial microbes on the phyllosphere (Leaf
Surface) support plant growth and health include; increasing nutrient availability;
activating plant defense mechanisms; producing antibiotics; out competing pathogens;
and providing growth-stimulating substances or enzymes.
If you colonize beneficial micro-organisms on leaf surfaces and into the root zone,
the bad microbes have literally no place to live and grow.
Compost teas have shown very impressive disease suppression in trials conducted at
Oregon state, Arizona state and Cornell University. Benefits of a “good” fungal colonization
are the suppression of powdery mildew, downey mildew, snow mold, red thread, fairy
ring, brown patch and summer patch. Care should be taken on using home made teas
on eatable produce in that there may be harmful bacteria in the brew.
Temperature — Plants will close most of the stomata openings or curl the leaf at
87 F. This is done naturally so a plant does not transpire much water during the
heat of the day. Most people choose to foliar feed in the very early morning or
late evening when conditions are coolest. You should try to avoid using a foliar
spray if the temperature is over seventy-five degrees Fahrenheit.
Humidity - High humidity levels help overcome leaf curling and stomata closing.
With the stomata closed very few nutrients are assimilated into the plant. Do not
spray during or just before rain so the material does not get washed away.
Water – Water quality is important. If you are using water from a source that
has chlorine in it put the water in an open container and let it sit for 12 hours
so the chlorine will dissipate. Well water needs to be checked to make sure its pH
is in a range from 5.8 to 6.8, if not you need to add either an acidic product to
bring the pH down or an alkaline product to bring it up into this range. With rain
water make sure the surfaces that you are collecting it from do not add harmful elements.
Rain water from copper roofs or wood roofs where the shingles were treated with copper.
There is a worry about harmful bacteria in some water sources; in these cases a
little hydrogen peroxide is effective. Get a good pH meter and check your water and
the final solution every time you get ready to spray.
Salt Index — Spray solutions should have a salt index of 10 or less. Application
of IFA low salt index products will result in an osmotic absorption, which is quick,
clean and complete absorption of nutrients into plant tissue without tissue damage.
Application methods – You want to use as fine a mist as you can. If you are working
with a small number of plants a common quart spray bottle will work. For larger number
of plants a hand held pump sprayer is useful and for large amounts of plant a backpack
sprayers is great. Leaves are able to absorb the nutrients through the stomata, or
pores, which cover each leaf. The majority of these are on the underside of the leaf.
To ensure your best absorption of your spray, completely cover the leaves, both top
pH Balance - Much like your nutrient solution, the pH of your foliar spray should
be slightly acidic, with a pH of around 6.0. This will allow the solution to penetrate
the film on the leaf and be absorbed easily into the leaf. Using a good quality water
pH meter measure your pH and make any adjustments necessary with a water pH meter.
Gardening supply stores usually sell pH-adjusting chemicals by the generic names
pH up and pH down. .
A supplement, not a substitute – Remember that foliar is very useful, but cannot
replace healthy soil and roots. A plant’s roots purpose is to supply large amounts
of nutrients which you cannot get through foliar feeding. Foliar feeding can do the
Provide nutrients after transplanting. Until new roots are formed, the plant is
completely dependent upon stored nutrients to maintain itself, but foliar feeding
can minimize the shock and keep the plant growing.
Cold soil in early spring growth can be limit perennials, even when the air is
warm. Soil microorganisms are not capable of converting nutrients into forms available
for roots to absorb. Foliar feeding can quickly provide the needed nutrients to the
plants, thus allowing the plant to begin growth before roots can furnish needed nutrients
from the soil.
Provide peak need feeding when the plant can demand nutrients faster than the roots
can furnish them. Foliar feeding can influence flowering, fruit set, fruit size,
amount of vegetative growth, among other things.
Allows flexibility in supplying nutrients. Small imbalances in the soil can lock
up various nutrients, foliar feeding allows the ability to correct these problems.
Iron is in most soils but is very hard to get into a form plants can use.
Can provide nutrients during times of plant stress. It can protect plants from
the damage of weather extremes and drought.
Help provide disease and insect protection.
Some plants, such as azaleas, rhododendrons, camellias, and blueberries, thrive
in low pH conditions so they can not extract iron unless the soil is quite acidic
(5.0 or less) and may need a foliar spray boost even in slightly acidic soil.
Brix Scale growing – ( http://www.tandjenterprises.com/brix_equals_quality.htm) This is where growers are trying to get the best quality end product possible.
The higher the Brix Scale reading the higher the quality of the product. The higher
the Brix Scale number is for what you r growing the lest problem you are going to
have with disease and harmful insects. California wine growers have been using this
method for years to know what they needed to add to the vines to get the best grapes.
There is no one singular foliar spray mixture that is going to give you what you
need at all times. It depends on what you are trying to accomplish and where in the
growing cycle the plant is along with what is locked up in the soil at the time.
A partial list of what can be used:
N-P-K – any water soluble fertilizer can be usedbut be careful to use very small
amount to keep salt concentrations low and prevent to burning. Thingslike fish hydrolysates,
alfalfa pellet tea, Blood meal, bone meal and others.
Trace Nutrients and Biology - Complete Humates, Compost tea, Worm Tea, Seaweed
Herbal extracts from plants – Cyan pepper, garlic, stinging nettles, yarrow tops,
chamomile, oak bark, valerian and others
Sticker/Spreader – these help hold your spray to the leaves and spreads it over
more of the leaf surface. Biodegradable vegetable oil such as Dr. Bonner’s soap or
a fish oil product. Use these with care because some can damage leaf biology.
This is just a small sampling of what is used in foliar sprays.
FOLIAR SPRAY All Purpose
1 Tablespoon liquid Humic Acid. Recommend a complete natural Humate such as Turf
& Garden Pro (www.turfprousa.com ). Be sure of country of origin on Humates. Many
come from countries where quality can be suspect.
1 Tablespoon Liquid Fish. Recommend a fish hydrolysate such as Mega Green ( www.multibloom.com/
). We recommend fish hydrolysates over fish emulsions.
1 Tablespoon Liquid Seaweed. Recommend North Sea products such as Maxicorp Seaweed.
1 Teaspoon Blackstrap Molasses
1 Teaspoon Apple Cider Vinegar
1 Gal. Water - Shake well! (If you are on city water let it sit outside in an open
container for a day to naturally de-chlorinate – better yet use rain water.) Use
this to build up cold and heat resistance for all your plants plus adding to the
Summery: Foliar feeding is a great tool to increase plant health and help produce
a quality end product whether it be great produce, magnificent flowers or a great