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Boost your plants with a liquid feed

We could all do with a drink sometimes and plants are no exception. Foliar/liquid feeds make the perfect liquid lunch!

What are Liquid fertilizers?

Liquid fertilizers are fertilizers that come in a liquid form, most commonly as a concentrate. In other words, the grower must dilute the liquid fertilizer in water before feeding it to the garden. Either the soil or the plant can be watered. Liquid fertilizers are faster-acting than granular fertilizers.

  • With a liquid fertilizer the gardener has control over dosage and how often the plants are being fed. It is much easier to tailor a feeding program to the garden’s current stage of growth with a liquid fertilizer than with a dry fertilizer.
  • Liquid fertilizers also give increased control when problems arise.
  • It is a fast way to supply micro-nutrients, such as Boron and Manganese, which the crops don't need in such quantities, but which may not be so readily available in the soil.
  • If the crops are under stress from drought, pest-attack or disease, it's definitely worth giving them a squirt of encouragement by foliar feeding. An ailing plant can perk up quite visibly after spraying with, for example, liquid seaweed, OPF or Vinasse.
  • Liquid fertilizers can be invaluable if you’re growing cold-tolerant crops that start growing when soil temperatures are low for example, overwintered spinach or garlic/onions. Nitrogen held in the soil is difficult for plants to take up until soil temperatures rise above 10 degrees Celsius, meaning plants can experience a slow start because of a temporary nutrient deficit in late winter and early spring. Liquid fertilizers provide a boost until the soil warms up.
  • The leaves of vegetables in the greenhouse are softer, therefore they can absorb the foliar feeds better.

Important points when using liquid fertilizers

  • Spray the whole plant, and make sure you cover both the upper and lower surface of leaves.
  • Don't spray in direct sunshine, as the drying of the salts in the solution may result in leaf scorch.
  • Avoid overhead irrigation until the spray has dried, and do not to spray just before rain, as extra water will dilute the solution and wash some of it away.
  • Do not apply foliar feeds during the warmest period of the day, during hot weather conditions, or to wilted plants. It is best to foliar feed very late in the evening or even very early in the morning. Dew will help absorption.
    Birchmeir fertilizer mixing sprayer
  • Foliar sprays dry quickly when applied at high temperatures, reducing absorption of the nutrients in solution.
  • High light intensities can improve foliar uptake.
  • High humidity favours nutrient uptake through the leaves in two ways; by decreasing the rate of drying of the applied nutrient solutions, and by causing the cuticle to absorb water from the atmosphere and swell, which results in the formation of more polar pores.
  • Aging leaves develop thick cuticles that hinder foliar uptake. Young developing leaves have thin cuticles and are therefore more efficient at foliar uptake.
  • Higher spray volumes result in more uniform coverage and more effective foliar feeding.
  • Foliar applications should wet the entire canopy, especially the new leaves.
  • Always look at the dilution rates when using liquid feeds - a little goes a long way!

Different types of Liquid feed

Liquid NPK fertilizers

Vinasse is a by-product of the sugar industry, made through fermentation of molasses.  Vinasse liquid can be taken up by plant foliage immediately because the Nitrogen is available in Protein form. The proteins together with the sugar residues have the additional effect of stimulating the micro-organisms in the soil. It is very effective where plants show signs of nutrient deficiencies like stunted growth or yellow leaves.  The natural combination of Nitrogen and Potash - N(4.5) - K(6) -  (together with trace elements and small amounts of Phosphate, Sulphur and Magnesium) is ideal for all plants which require high Potash levels.

OPF (Organic plant food) The organic base of OPF consists of plant based raw materials with high levels of natural sugars. Specific fermentation processes upgrade the organic materials to an excellent fertilizer. Natural vegetable raw materials have low amounts of salt, reducing the risk of root- and leaf burn damage. The high content of trace elements and sugars supports a healthy soil life and provides healthy and stable plant growth. The amino acids in OPF originate from plants and are therefore easy to absorb, even at low temperatures. OPF is a natural product and contains no preservatives. Available forms -  4:2:8, 7:2:3, 5:2:2

Liquid Seaweed for trace elements

Liquid seaweed enables plants to make more efficient use of nutrients, leading to improved yield, taste and colour - and increased resistance to pests and diseases, drought and marginal frosts.  Concentrated liquid seaweed extract is made from seaweed (Ascophyllum nodosum) freshly harvested off the Irish Atlantic coast. Seaweed extract increases the strength and health of seedlings and plants Regular use has a cumulative effect on your garden. Liquid seaweed is great nourishment for plants but is different from most N P K fertilizer treatments.  In fact seaweed only contains a little K – potassium.  But it has many other minerals, vitamins, and enzymes that are natural growth stimulants. Many of these are not found elsewhere. These nutrients fuel the plant cells’ growth, and this results in healthier, stronger, and more disease-resistant plants.

Biostimulants (feed and protect)

Biostimulants  encourage the plant to defend itself from pests and diseases. When absorbed after watering or spraying the active elements in biostimulant products will both increase the plants resistance and develop a defence system.  This is a self-induced system - thus a natural weapon against attacks by aggressors, like fungal diseases and pests. The growth of the plants is stimulated and the plants will be stronger and healthier.  A Biostimulant is systemic and moves within the vascular tissues of the plant.

Fruit Hill Farm have range of products made from a highly concentrated blend of herbal extracts in a water base. They are environmentally friendly, break down in the soil and leave no residues behind. They can be used against insects and fungus/moulds on both herbaceous and woody plants.  Very good against carrot fly.

Home made liquid feed with Comfrey or Nettles

Nettles make an excellent liquid feed

You can make your own liquid fertilizer from comfrey of nettles - both are rich in potash.  To make liquid feed you will need a quantity of nettle/comfrey leaves and a large barrel or bucket. Break up the leaves a bit and jam as many as possible into the container. Weigh them down with a piece of wood and cover with water. Cover with a lid of some sort to keep out rain and flies. After about six weeks in isolation (it smells a bit) you will have a rich dark brown liquid that can be diluted as a feed for your tomatoes or potatoes. The residual sludge can be put on the compost heap. For a stronger less smellier feed don't put water into the barrel.  Collect the brown liquid as it drips from the decomposing leaves.  A barrel with a tap is good for this method.


If you are using a liquid feed you will need a sprayer.  Look for one that is high quality, easy to fill and easy to clean.  It should come with a range of spraying options from fine - coarse to give you greater control.  You could also consider a mixing sprayer which can be attached to a hose-pipe which will automatically adds liquid fertilizer to the water in the chosen dosage.

Liquid feeding is especially effective if a drip irrigation system is set-up.


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