A fertilisation calendar orders the year by what the plant is doing (dormancy, budbreak, flowering and fruit set, swelling and ripening, post-harvest), not by months. In organic farming it is built with materials from Annex II and with the dosage each data sheet publishes; and since 2026 a fertilisation plan is, in addition, an obligation for most production units.
How to read this calendar: seasons, stages and three crop groups
The three groups are the ones in our data sheets: fruit and woody crops, vegetable crops and arable crops. Each season carries a table: group → stage → what is applied → data sheet. Each cell is the literal moment published by the data sheet; what is missing is a dosage per stage: the dosage is read on the linked data sheet, by route and by crop group. How a full dosage table is read is explained in how to read a fertiliser technical data sheet.
Autumn: post-harvest and dormancy
| Group | Stage | What is applied | Data sheet |
|---|---|---|---|
| Fruit trees | Post-harvest | Documented moment (“post-harvest” among the key moments) | UNIVERSAL |
| Olive grove | Dormancy, after the 4th treatment | No treatment with a published dosage at this stage | olive grove fertilisation programme |
| Vegetable crops with an autumn-winter cycle | Post-transplant, growth | Critical moments of development: post-transplant, growth, pre-flowering, fruit set and development | NPK 7-7-7 / 9-4-4 / 6-3-18 |
| Arable crops, cereal sowing | No stage of its own on the data sheet | The data sheets do not give a specific stage for cereal | respective ranges |
On the olive grove, autumn fertilisation does not have a foliar treatment with a published dosage: the fourth treatment of the programme (ripening, with POTASIO K20) already happened in summer, and dormancy follows. That is, therefore, the answer to “olive grove autumn fertilisation”: there is no documented fifth treatment.
By fertigation, where irrigation is available, HUMIC FULVIC+ALGAS is placed “at any stage of the growing cycle; with emphasis on the periods of highest nutrient demand”, with no effect attributed to it by the data sheet.
Winter: dormancy, soil and paperwork
No foliar application during dormancy, as a general rule: the plant is not at a stage of higher vegetative activity. Where irrigation is available, humic substances are applied by fertigation under the year-round rule: “split the input … at 10-15 day intervals”.
The boundary with spring is marked by the olive grove's own programme: the first annual treatment is placed “late February/early March”.
Winter is when the year's documents are drafted: the fertilisation plan (next section) and the soil and water analyses that support it.
Spring: budbreak, flowering and fruit set
| Group | Stage | What is applied | Data sheet |
|---|---|---|---|
| Olive grove, 1st treatment | Late February/early March | Start of the annual programme | olive grove fertilisation programme |
| Olive grove, 2nd treatment | About one month after the first | BORO and NITRÓGENO 16 in the tank | BORO · NITRÓGENO 16 |
| Olive grove, 3rd treatment | Olives set | CALCIO 880 in the tank | CALCIO 880 |
| Citrus and other fruit trees | Budbreak | Iron chlorosis window | HIERRO, see iron chlorosis |
| Fruit trees, flowering | Flowering | “Should be used especially during the flowering stage” | FÓSFORO 0-20-0 · FÓSFORO 20 LÍQUIDO · PK 20-20 |
| Fruit trees, post-flowering and fruit set | Post-flowering, fruit set | Vegetative stage, post-flowering and stages of highest vegetative activity | BORO · CALCIO 880 |
| Vegetable crops | Transplant, post-transplant, growth, pre-flowering | Critical moments of development | NPK · NUTRIPLUS |
| Arable crops (maize) | Sowing and growth | Data sheet moment | respective range |
Almond and avocado belong to the fruit trees group on our data sheets, with no stage of their own, distinct from the group's: they are fertilised with the fruit tree calendar above, not with a programme of their own.
Summer: swelling, ripening and heat
| Group | Stage | What is applied | Data sheet |
|---|---|---|---|
| Fruit trees, fruiting | Fruiting | “Especially during the fruiting stage” | POTASIO K20 |
| Citrus | From the start of colour break | Data sheet moment | POTASIO K20 |
| Olive grove, 4th treatment | Ripening | POTASIO K20 in the tank | POTASIO K20 |
| Fruit trees, swelling and ripening | Fruit swelling and ripening | Data sheet moment | NPK 6-3-18 |
| Vegetable crops in production | Weekly applications | “Between 2 and 4 depending on the crop” | CALCIO 880 and others |
| Arable crops (maize) | Flowering-filling | Data sheet moment | respective range |
UNIVERSAL names, among its key moments, “ahead of expected stress”: it is a documented application moment on the data sheet, not an effect attributed to the product.
Some data sheets mark literal summer conditions: FÓSFORO 0-20-0 recommends applying it “early morning or late evening to reduce the risk of phytotoxicity”; MICROELEMENTOS warns to “avoid foliar treatments under extreme drought, humidity, rain or forecast extreme conditions”; BORO warns “do not apply at high temperatures”. When the foliar route suits and when fertigation does is covered in foliar fertiliser or fertigation.
The olive grove: the only calendar with dosages we publish
Of the crops in our range, the olive grove is the only one with its own fertilisation programme and a published dosage per treatment. Its moments, in summary: 1st late February/early March, 2nd about one month later, 3rd once the olives have set, 4th at ripening, young olive trees with a monthly foliar treatment, and a minimum of 3 irrigations in the fertigation programme. The full detail, with its tanks and its litres, is in the olive grove fertilisation programme; this guide does not repeat that table, and does not name the two products in the programme that are not publishable in content.
The rules that hold all year round
The general cadence, repeated across several data sheets: “generally weekly applications, between 2 and 4 depending on the crop”. In fertigation, the rule is to split the input and respect an interval: “split the input … at 10-15 day intervals”, with each product's own limit (“maximum 6 L/ha”, “maximum 10 L/ha” or “maximum 10 kg/ha”, depending on the data sheet). Several data sheets ask to “pre-dilute before pouring into the tank” before preparing the mix. And a warning our MICROELEMENTOS data sheet makes explicit: “doses are general recommendations; they depend on the crop, phenological stage, level of deficiency and soil type; use under technical advice”. Soil analysis is the basis of the plan; foliar application or fertigation correct within the season.
The mandatory fertilisation plan and the farm logbook
Royal Decree 1051/2022, as amended by Royal Decree 934/2025, sets out rules for sustainable nutrition of agricultural soils in Spain. The consolidated text is on boe.es.
Who, and from when
The holder of each production unit is responsible for drawing up and applying a fertilisation plan. The general obligation comes into force on a staggered basis from 2026; small rain-fed units, units used only for self-consumption pasture or fodder, and unfertilised pasture are excepted. The exact dates for each case need to be checked against the consolidated text in force on the day of the enquiry, because they have been revised more than once since the regulation was first published.
What the plan covers
The plan identifies the production unit's plots, soil data from a plot representative of each crop sheet, rainfall and available water resources, the recommended dose of each nutrient and emission-reduction measures. In areas vulnerable to nitrate pollution, and later across all production units, the plan must be backed by a fertilisation adviser.
What goes in the farm logbook
The farm logbook includes a “Fertilisation” section, where each application is recorded with its dose and its date, within a limited period from application. The smallest holdings are exempt, within the area and irrigation limits the regulation sets. Each autonomous community publishes its own logbook template: we do not link to it here, because it is not on our source list.
What a manufacturer puts in that plan
The published data sheet of each product is the input's document; the input attestation is the justification for its suitability in organic farming, covered in how to check whether an input is suitable for organic farming. We are not fertilisation advisers: the plan is drawn up and signed by whoever holds that qualification.
Frequently asked questions
When is the olive tree fertilised?
With the olive grove's own programme: four foliar treatments through the year (late February/early March, one month later, with the olives set and at ripening) plus a minimum of three irrigations. The detail is in the olive grove fertilisation programme.
When should fruit trees be fertilised: in autumn or in spring?
Both, with a different stage each time. In autumn, the documented moment is post-harvest; in spring, budbreak, flowering and fruit set. No data sheet publishes a month outside the olive grove programme: what exists is the stage.
When are citrus and orange trees fertilised in spring?
In the budbreak window, which is also the stage at which iron chlorosis is treated when it appears. The HIERRO data sheet publishes dosages for the fruit trees group, which citrus belongs to.
Should fertilisation happen in summer?
Yes, at the fruiting and ripening stage: that is when several data sheets place their moment (POTASIO K20, NPK 6-3-18) and when the olive grove carries out its fourth treatment.
Is a fertilisation plan mandatory?
Yes, for most production units, with the exceptions set by Royal Decree 1051/2022 as amended by Royal Decree 934/2025. The exact dates for each type of unit are in the consolidated text on boe.es.
What do I record in the farm logbook about fertilisation?
Each application, with its dose and its date, in the “Fertilisation” section of the logbook, unless the holding is exempt because of its size. The logbook template is published by each autonomous community.
The olive grove fertilisation programme and the full catalogue bring together the data sheets and dosages cited in this calendar. To resolve a question about a specific crop or product, the technical enquiry exists for that.