Many will want to answer that, no, we do not fertilize during the winter. Fertilization must be done during the growth period of the plants and, in winter, our indoor plants are not in the growth period. It is better to wait until the days get longer in spring to start fertilizing again.
It's not false.
But that's not entirely true either.
In fact, our houseplants do not go into total dormancy during the winter. It is true that they seem to be in slow motion and that when spring arrives, bam!, they come out of their torpor and offer us many new shoots. As if they knew exactly when to start pushing again. As if they felt the coming of brighter days, and that the increase and intensification of the lighting made them explode with happiness. This state of exuberance, when compared to that of calm in which they find themselves during the winter months, can lead us to say that they sleep from October to March...
But, during these months, the plants we keep near windows and those to which we provide artificial lighting are not completely dormant in our temperate climate homes. They have a metabolic activity which continues, even in winter. Their cells don't stop working, they slow down. They continue to produce glucose using solar energy (or that of our lamps which imitate solar energy) and thus produce their food. Photosynthesis continues. But quite simply, the metabolic activity of plants is proportional to the illumination they receive. The less light, the less photosynthesis. It's normal. (Our article on artificial lighting is available here and it discusses photosynthesis).
It is in particular because of this change of pace that we must water our houseplants less during the less bright months. Since their metabolic activity is slow, plants consume less water. Come to think of it, we too are less thirsty when it’s cooler…
And in fact, fertilization follows the same logic. If the plant continues its metabolic activity very slowly, if we see that it is showing signs of growth, even slowly, we can fertilize it, but very slowly.
To fully understand the nuance between fertilizing during the active growing period and fertilizing during the winter months, you need to understand how fertilizers work, generally speaking.
What is NPK?
On fertilizer containers, there are 3 numbers, which correspond to the percentage of primary elements : nitrogen (N), phosphorus (P), potassium (K). Each element plays a different role and this diagram can help us remember them.
Nitrogen (N)
Nitrogen is the element that helps plants grow, develop foliage and aerial parts of the plant. It also contributes to the color of the foliage. Indeed, nitrogen is a component of chlorophyll and, if this element is lacking, the entire photosynthesis process is affected. Nitrogen is also a food source for soil microorganisms.
We recommend a fertilizer rich in nitrogen, for example, for seedlings or indoor plants with green foliage. It is also interesting for conifers, lawns and leafy vegetables.
Phosphorus (P)
Phosphorus contributes to flower development and root system growth. Fertilizers designed for flowering and rooting are rich in phosphorus. Obviously, by strengthening the root system, phosphorus contributes to the growth of the plant.
In summer, when you want your annuals to flower to the fullest, you should buy a fertilizer rich in phosphorus. It can also be recommended to help the rooting of newly established plants.
Potassium (K)
Potassium has a role to play in the general resistance of plants to cold, drought, insects and diseases. It is like a shield for the plant. It also participates in the development and ripening of fruits.
We often recommend fertilizers rich in potassium in the garden for vegetables, for example, and also in the fall, to help our outdoor plants get through the winter.
Complete fertilizer / incomplete fertilizer
A complete fertilizer includes these three elements. They may or may not be in equal doses. A so-called incomplete fertilizer is composed of one or two elements. It is not necessarily less interesting, it all depends on the needs. We must take into account that, if we have good soil, the elements are present there naturally. Sometimes it is not necessary to have a fertilizer that provides all three elements. We can also alternate the sources of fertilizer, so as to vary the contribution that will be made to the plants.
Secondary elements and trace elements
To grow, plants not only need these three primary elements: nitrogen, phosphorus and potassium. They will draw calcium (C), magnesium (M) and sulfur (S) from the soil. They will also draw from it a whole variety of trace elements, required in smaller quantities, such as chlorine (Cl), iron (Fe), manganese (Mn), boron (B), zinc (Zn ) copper (Cu), nickel (Ni) and molybdenum (Mo). These elements are naturally present in the soil. But sometimes, for our indoor plants, they run out and we have to renew them.
Synthetic fertilizers / natural fertilizers
Synthetic (chemical) fertilizers come from chemically transformed substances and have NPK proportions most of the time above 10 (for example 20-20-20, 15-30-15, 10- 52-10). They are powerful and act very quickly on the plant, because they are assimilated directly by the roots. However, their effect does not last very long, which is why the intake must be renewed frequently. It should be noted that they often have an influence on the pH of the soil, which is why it may be interesting to vary them. They do not promote soil microbial life beneficial to plants. Studies show that they even have the opposite effect.
Natural fertilizers, for their part, will rather draw on elements such as algae, fish, bones, manure from various animals or insects, bones, etc. They have proportions that are most of the time below 10 (5-1-1, 2-4-6, 5-6-1). They are not immediately assimilated by plants, because they first nourish the soil. They must be broken down by soil microorganisms before being available to nourish plants. Their effect is therefore less immediate, but much more lasting. And these fertilizers have the advantage of providing the substrate with secondary elements and trace elements which the plants need and which are not offered by the majority of synthetic fertilizers. They contribute to better quality soil, richer in organic matter.
Fertilizers to stimulate a plant that is not growing
Contrary to what we might believe, this statement is false. Do not fertilize plants that do not show signs of growth. Their roots will not be able to assimilate mineral salts. These will simply remain in the soil and in the long run, this will be harmful to the plants. It is better to fertilize a growing plant to compensate for its efforts.
Let's not forget that the plants we grow in our homes are in closed pots and in a substrate that does not contain active microorganisms (unless we provide: Soil activator ) nor rain to wash them away. excess mineral salts and regulate all this, as in nature.
Earthalive's soil activator can be integrated into the substrate or watering water at any time, summer or winter. It will have the effect of increasing biological activity in the soil. It does not contain any genetically modified organisms or synthetic chemicals, but micro-organisms which, once released into the soil, will allow better growth and guarantee the health of the plant. Soil activator improves water holding capacity of soil, helps plants deal with transplant shock, increases nutrient uptake, boosts nitrogen levels in soil, releases nutrients from matter organic, solubilizes phosphorus and improves the availability of micronutrients.
Which fertilizer to choose for fertilizing in winter?
As mentioned above, in general, plants should be fertilized in spring and summer because they are less hungry and less thirsty during the colder months, which have a shorter period of sunlight. In winter, most plants are not in a state of active growth, so they must be fertilized carefully.
We now understand why a synthetic fertilizer, very powerful and quickly absorbed, is not appropriate for a plant whose metabolic activity is slow. It can even harm it, or rush it and the result will be long, weak shoots, without tone, because the plant does not have what it needs at this time of the year to have robust and dense growth.
Choosing a natural, gentle fertilizer, which will act on the soil even before being assimilated by the plant, will promote much more balanced development and can suit its winter rhythm. You can even reduce the dosage indicated on the label and give regular microdoses, which will have the effect of vitamins throughout the winter. The result will be a plant which will not have grown tremendously in winter, but which will have gained strength to burst with happiness in spring, and which will have a substrate rich in organic matter and thus capable of offering it all the elements it needs. she needs. Which is all the more important during the period of active growth.
Here are the options available to us for winter fertilization
Stimyla photostimulating natural fertilizer (0.1 – 0.2 – 1.0) based on marine algae extracts and natural bioactive compounds can be applied by foliar spraying or irrigation water. It offers: faster growth, greener foliage, abundant and longer flowering, accelerated development of seedlings, facilitates cutting of plants (the manufacturer suggests soaking cuttings and seedlings in it), better quality of fruits and vegetables, increases plant vigor and resistance to disease.
Fertilizer Vit-Alg from Acadie (0.3 – 0.1 – 0.2) is a ready-to-use marine algae solution. The container, equipped with a spray bottle, is ideal for weekly foliar applications. This product is perfect for those who prefer not to make the mixtures themselves. Composed of Ascophyllum nosodum (black seaweed), this fertilizer, which can be used outdoors as well as indoors, increases the growth rate and beauty of flowers, stems and foliage. It is approved for organic farming.
Fresh Algae Fertilizer from Acadia (0.6 – 0 – 6) is a concentrate to be diluted according to label recommendations. It can be used as a foliar spray or when watering. This fertilizer is also composed of Ascophyllum nosodum (black seaweed) and can be used outdoors as well as indoors. It offers relatively the same benefits as Vit-Alg (increases the growth rate and beauty of flowers, stems and foliage), but is more economically advantageous. It contains 60% organic matter and is approved for organic farming.
Fish hydrolyzate from Acadia (2 – 4 – 0.5) is a concentrate resulting from a cold hydrolysis process of fish which allows the preservation of a maximum of amino acids offering a high supply of nutrients. It allows deficiencies to be quickly corrected, encourages the proliferation of bacteria beneficial to the ecosystem, stimulates roots and flowering, nourishes the soil with its rich nutrients, and increases the sugar level of fruits and vegetables. It contains 37.5% organic matter and is approved for organic farming.
This product is ideal for use in alternation with algae fertilizer, because together they provide nitrogen, phosphorus and potassium.
Note to sensitive noses however, used indoors with closed windows, the smell can be bothersome.
Liquid marine algae from Bionik (0.36 – 0 – 0.22) is a concentrate to be diluted obtained by a transformation process (micronization and fermentation) of dry algae into a liquid product. In addition to containing nitrogen and potassium, this product also contains 0.5% calcium and 0.3% magnesium. Bionik claims that growth will be twice as active, that its fertilizer acts as an anti-stress for plants (drought, heat, cold, transplantation) and that it promotes rooting. Can be used as a foliar spray and when watering. Approved for organic farming.
Super Fly insect droppings from Gaïa Green (2 – 1 – 1) is a dry fertilizer composed of droppings of black soldier fly larvae. Although new to organic growers, this digested material has played an important role in plant nutrition for millions of years. Super Fly insect droppings are rich in essential nutrients.
You can use Super Fly insect droppings in different ways: mix it with watering water, apply it as a foliar spray or add it directly to potting soil (either on the surface or mix it before repotting). Mixed with watering water, it helps fight soil midges (sciarids) and fungal diseases. It is a fertilizer that contributes to the health and immunity of plants. The slow but easy release of nutrients provides a rich source of chitin, beneficial bacteria and fungi for the soil. It is approved for organic farming.
Nutrifrass from CricketNutris (2 – 3 – 3) is somewhat in the same fertilizer category as Super Fly. It is a dry fertilizer that can be applied directly to the surface of the potting soil or mixed into the substrate. It can be used for indoor and outdoor plants as well as on the lawn. Nutrifrass is composed of locust droppings, an organic raw material rich in essential nutrients, insect biomarkers, chitin, beneficial microbes and beneficial fungi. This fertilizer promotes plant resistance to disease by encouraging them to generate high immune responses.
Fertilizer for seedlings, fine herbs and houseplants from Bionik (available in 85 g format: 5 – 2 – 6 and in 400 g format: 6 – 1 – 5) is a non-water soluble fertilizer that is mixed with the soil. It is mainly made from snow crab meal, seaweed, alfalfa and feather meal. Interestingly it contains 4% calcium (which is quite high) and 0.9% magnesium. It is a complete fertilizer, containing all the essential elements for growth, and perfectly balanced for optimal and abundant growth of foliage. Bionik claims that plants will produce twice as much foliage with a single application of this fertilizer. Approved for organic farming. 
NuMix Citrus and Fruit Fertilizer (6 – 2 – 6) is granular. It is deposited on the surface of the substrate or can also be incorporated into it. It is a fertilizer enriched with potassium, magnesium and calcium, which improves the sugar concentration of fruits, making them tastier. It is specially developed for lemon trees, lime trees, orange trees, etc. It is approved for organic farming.
All of these fertilizers are gentle enough to be used in winter. They have the advantage of being natural and contributing both to the health of your plants and to the quality of the substrate from which they draw life.
So we can continue to pamper our plants all season long!
