How To Fertilise or not in a  Greenhouse Plant (Part 11)

Greenhouse fertilising

A plant newly potted will need some time so that it can grow new roots in order to absorb or take in the fertiliser that you will apply.

How you fertilise and what type of fertiliser you use is dependent on what kinds of plants or crop you grow in your greenhouse, because every crop has a particular requirement with regards to nutrients, and this requirement should be met.

For house plants, it is usually much easier to fertilise a large group together. Generally, plants need to be fertilised every one or two months while there is rapid growth and all throughout the winter season, twice or once only.

Alternatively, you can apply the fertiliser more frequently when using a liquid fertiliser diluted in water; this familiarises certain plants that otherwise be injured when you use a fertiliser of full. Generally half of the recommended strength or dosage means that you use only half fertiliser in every plant.


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Annual plants can flourish very rapidly and will require fertilisation every two weeks throughout their short season. A few flowering plants such as the Azalea must not be applied fertiliser while in their blooming or flowering stage.

Most fertilisers that are generally used have considerable amount of nitrogen (50 percent); they contain the preferred amount of nitrate f and are usually labeled and identified as peat-liteî. This type is preferred and recommended for greenhouse hobby use. The N-P-K ratio can be verified by reading the label that is found at the fertiliser bag.


Fertilisers are usually applied at the amount or ratio of 200 ppm nitrogen fertiliser like 21-5-20 or 20-10-20 This is completed by continuous liquid application; this ratio is the basis for mostly all pot grown greenhouse plants. The rate may be adjusted downward or upward depending on the plant that is grown.

Any pre-mixed or ready mixture of fertiliser for the kind of plants that you grow is acceptable; for most flowering and foliar plants. An N-P-K ratio analysis that is similar to 1-2-1 will supply a balanced growth.

Soluble fertilisers can be conveniently applied and deliver faster results compared to solid fertilisers or slow releases gravel-like fertilisers. Just apply the solution in a manner like you are watering your plants, however, instead of water, use the fertiliser solution, making certain that the plant soil is slightly moist before application. You should never apply fertiliser solution onto plants with dry soil the roots can be injured by the fertiliser chemicals; moist soil further dilutes the chemicals.


Apply fertilisers always following or much weaker dose than the suggested dilution strength, and not stronger, as seedlings, newly established cuttings, and developing plants will derive benefit from much weaker solutions; stronger solution will only injure young and soft roots.

There are many injections or siphon devices available in the market to make application of soluble fertilisers much easier; however, when you use them, be certain that you install backflow preventers in order to keep the nutrients or chemicals in the fertiliser solution from contaminating your water supply in the home. Likewise do not water your plants with a water-softened water due to its high salt content.

Recommended fertiliser products

A mixture of flora-micro, flora-bloom and floragro, will enable you to combine a wide range of many different nutrient blends or solutions in order to fulfil the specific requirement of virtually any kind of plant that you grow, and at different stages of the plants life.

This is accomplished by changing the mixture combinations as well as the general strength of your solution. You can combine different ratios and different strength of nutrients by adjusting the water quantity when blending floragro, flora-micro and flora-bloom.

Calcium Nitrate in Greenhouse Grade may be used in large scale growing. It can be economical to buy fertilisers in 50-pound quantities. Calcium Nitrate in Greenhouse Grade and Hydro-Grow are great combinations to achieve complete nutrient blend.

Greenhouse plants need your attention. Check on them each day to be sure that they are free from disease and pests and act immediately if there is any problem. It is a wise idea to know the characteristics of each type of plant that you grow in your greenhouse. Have fun taking care of your plants!


But you can also opt for a vertical farming which uses very little soil (than no pesticides needed and less farming land) less water but controlled nutrients to the plants. Solar energy or sustainable energy to replace the sun light would be the solution for growing fruit and vegetable especially in urban areas. Vertical farming will be the next topic.

Greenhouse (Part12) (Vertical Farming and Container Farming are ways of avoiding pesticide) will be on What’s On In Bromley.

Jean Michel

What’s on in Bromley.