Organic potting compost fertilised with worm humus
Regular price
$19.00
Regular price
Sale price
$19.00
Unit price
/
per
| Volume | Price | Price per L | vs 25 L |
|---|---|---|---|
| 25 L | $19.00 | $0.76 | — |
| 50 L | $27.00 | $0.54 | −29 % |
Plagron's Royalmix is a fertilised organic potting compost, based on light and dark peat, fibres, perlite and earthworm humus. Fertilised solely with organic fertilisers, it feeds the plants for around six weeks after potting on, before a liquid fertiliser takes over.
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The summary
- Ingredients: a potting compost of peats, fibres, perlite and worm castings, with organic fertilisation.
- Feed duration: an organic fertiliser reserve for around six weeks.
- Organic follow-up: Alga Bloom or another liquid fertiliser from the fourth week.
- Target crops: repotting and pot cultivation of vegetables and herbs that are already rooted.
A rich, living compost that feeds your plants for six weeks
Plagron's Royalmix is a potting compost of peat, perlite and worm humus, pre-fertilised with 10.5 kg/m³ of NPK 5.5-11-5.5 organic fertiliser for around six weeks. It takes plants that already have roots, after rinsing, and stays out of the aquaponic circuit. Alga Bloom takes over from the fourth week.
Potting a tomato plant into bare compost means feeding it from the very next day. Royalmix starts from the opposite principle, since it is a compost already fertilised with organic elements, which covers the needs of the plants for about six weeks. It combines peat, fibres, perlite and worm castings, and its fertilisation is entirely organic. You can use it for potting on and growing vegetables, herbs or flowering plants in pots, in 25 or 50 L bags.
🪱 What's in the bag
Peat and fibres
The peat holds water and nutrients, while the fibres keep a coarse, airy structure.
Perlite
These very light mineral grains drain off excess water and let air circulate around the roots.
Worm castings
Worm castings provide stable organic matter and active microbial life.
Organic fertiliser
A load of 10.5 kg per cubic metre, with an NPK formula of 5.5-11-5.5, feeds the plants for six weeks.
Measured in water, the pH of Royalmix lies between 6.0 and 7.8, and its conductivity reaches 1.6 mS/cm, according to the French label. Dry matter makes up 38% of the raw product, of which 68% is organic matter, and each dry gram holds 5.3 ml of water. Conductivity reflects the quantity of dissolved salts, and therefore of immediately available nutrients. A mid-range value like this suits plants that are already rooted, whereas young roots prefer a leaner medium. The coarse structure of the mix keeps plenty of oxygen between the particles while still retaining water well, which spares you both suffocation and rapid drying out of the root ball.
The 10.5 kg of fertiliser per cubic metre works out at about 10 g per litre of potting compost, or roughly a hundred grams in your 10 L pot. As this fertiliser is organic, it does not dissolve all at once: the micro-organisms in the compost break it down gradually and release its nutrients as the plant grows. Its formula is twice as rich in phosphorus as in nitrogen and potassium. After about six weeks, this reserve runs out, and feeding must then be done through watering.
Take over with an organic fertiliser from the fourth week
A liquid organic fertiliser takes about two weeks to become available to the roots, the time it takes for the life in the compost to break it down. By starting the feeds in the fourth week, you therefore have assimilable nutrients available at the very moment the Royalmix reserve runs out. Alga Grow supports the development of the foliage, then Alga Bloom takes over on tomatoes, peppers or strawberry plants, at 40 ml per 10 litres in the fifth week of the 100% NATURAL growing schedule. You thus stay with an entirely organic feeding programme, consistent with that of the compost.
Keep Royalmix for plants that are already rooted
Its fertiliser load and conductivity suit plants that have already formed their roots, not seeds or fresh cuttings, which cope poorly with a rich medium. So sow in a light, low-nutrient compost, then pot on into Royalmix when the plants have two or three true leaves.
Royalmix is best suited to long-season crops in pots, which benefit from a well-fed start. For a tomato or pepper plant, allow a 10 to 12 L pot, so the 25 L bag fills two and the 50 L bag fills four. Perennial herbs, such as rosemary or sage, settle in for several seasons, and strawberries in planters find the richness they need to fruit. For salad planters, half Royalmix cut with light compost is enough, as these short crops use less.
💧 Preparing and watering
Before planting, rinse the compost to flush out the immediately soluble elements: fill the pot, pour in 5 to 10 L of water for a 10 L pot, let it drain, then set your plant in place. Over the following days, the conductivity rises gently, as the organic fertiliser continues to release. Then water by alternating wet periods with periods of slight dryness, which encourages the roots to grow downwards and explore the whole root ball. A pot that stays waterlogged all the time is starved of air, whereas a pot that dries out between waterings keeps its roots white and active.
🌱 Royalmix and aquaponics
Royalmix is a potting compost, and it must never be poured into the circuit of an aquaponic system. Its organic fertiliser would decompose in the water the fish live in, release ammonium and use up the oxygen that the fish and the filter bacteria need, while the fine peat particles would cloud the water and clog the filters. The grow bed is filled with an inert grow medium, such as clay pebbles, and the seedlings intended for the system's baskets are raised in an inert support rather than in compost. This way you avoid introducing into the water a supply of nutrients that you cannot control.
Potting compost, on the other hand, has its place around the system. Tomatoes in large pots, squashes or the herbs on the patio, which do not go into the grow bed, grow in Royalmix and can receive the replacement water from the tank during partial water changes. This water, rich in nitrate, already feeds the plants: measure the conductivity of the drainage water with a tester before adding your liquid fertiliser, and reduce the dose if it remains high. The guide on choosing a grow medium in aquaponics explains what goes into the system and what stays in the pots.
♻️ Reusing the compost
At the end of the season, the compost can be sieved to remove the roots and reused. Its fertiliser reserve is then exhausted, so you need to restore it before a new crop: mix it with fresh compost and with an amendment such as vermicompost, at one fifth of the volume, then add an organic fertiliser as soon as the plants resume growth. Compost that has carried diseased plants is better composted than reused, so as not to pass soil fungi on to the next crop.
An opened bag should be resealed and stored away from rain and sun, so that the potting compost keeps its moisture and its microbial life is not depleted. A compost that has become very dry can be rewetted slowly, by watering in small amounts and mixing by hand, because the water first runs off the dried-out peat without soaking in. You then have a uniform root ball again, ready for potting on next season's plants.
Technical specifications
The product
- Composition
- Peat, fibres, perlite, worm castings
- Pre-fertilisation
- 10.5 kg/m³, NPK 5.5-11-5.5Organic fertiliser, released gradually by the life in the compost
- How long the supply lasts
- About 6 weeks
- pH
- 6.0 to 7.8Measured in water, French label
- Conductivity
- 1.6 mS/cmOrganic matter, 68% of the dry matter
- Type of fertiliser
- Fully organic fertilisation
Usage
- Uses
- Repotting, pot cultivationPlants already rooted, not seedlings
- Before planting
- Flush with 5 to 10 L per 10 L pot
- Fertiliser top-up
- From the 4th weekAn organic liquid fertiliser takes about two weeks to take effect
- Watering
- Alternate between moist and slightly dry
2 further specifications are available in the detailed view.
In the box
- 1 bag of Royalmix of 25 or 50 L depending on the volume chosen
pH, conductivity and organic matter taken from the French label (NF U 44-551); pre-fertilisation, duration, flushing and follow-on feeding based on plagron.com.
Manufacturer and product safety
- Manufacturer
- Bertels B.V.
- Website
- plagron.com
Information provided under Regulation (EU) 2023/988 on general product safety.
Royalmix compared with mineral potting soils
Only Royalmix contains an organic fertiliser; Lightmix and Growmix are fed with a mineral fertiliser for one or three weeks.
Royalmix, Growmix or Lightmix?
All three bags share peat and perlite; Royalmix is the only one carrying six weeks of organic fertiliser.
| Built-in fertiliser | Fertiliser reserve (wk) | Fertiliser per cubic metre (kg) | Fertiliser formula | pH in water | Conductivity (mS/cm) | Plants accommodated | Rinse before planting | First liquid fertiliser | Price | |
|---|---|---|---|---|---|---|---|---|---|---|
| Light compost with peat and perliteYour choice | Mineral, 1 week | 1 wk | 1,5 kg | NPK 12-14-24 | 5.9 to 7 | 1,1 mS/cm | Young plants and rooted cuttings | No | After the 1st week | $12.00 |
| Pre-fertilised potting compost forYour choice | Mineral, 3 weeks | 3 wk | 1,8 kg | NPK 12-14-24 | 5.7 to 6.7 | 1,7 mS/cm | Plants already rooted | No | From the 4th week | $15.00 |
| Recommended Organic potting compost fertilised withYour choice | Organic, 6 weeks | 6 wk | 10,5 kg | NPK 5.5-11-5.5 | 6.0 to 7.8 | 1,6 mS/cm | Plants that are already rooted, after rinsing | Yes | From week 4, organic | $19.00 |
Light compost with peat and perlite
Built-in fertiliserMineral, 1 week
Fertiliser reserve (wk)1 wk
Fertiliser per cubic metre (kg)1,5 kg
Fertiliser formulaNPK 12-14-24
pH in water5.9 to 7
Conductivity (mS/cm)1,1 mS/cm
Plants accommodatedYoung plants and rooted cuttings
Rinse before plantingNo
First liquid fertiliserAfter the 1st week
Pre-fertilised potting compost for
Built-in fertiliserMineral, 3 weeks
Fertiliser reserve (wk)3 wk
Fertiliser per cubic metre (kg)1,8 kg
Fertiliser formulaNPK 12-14-24
pH in water5.7 to 6.7
Conductivity (mS/cm)1,7 mS/cm
Plants accommodatedPlants already rooted
Rinse before plantingNo
First liquid fertiliserFrom the 4th week
Organic potting compost fertilised withRecommended
Built-in fertiliserOrganic, 6 weeks
Fertiliser reserve (wk)6 wk
Fertiliser per cubic metre (kg)10,5 kg
Fertiliser formulaNPK 5.5-11-5.5
pH in water6.0 to 7.8
Conductivity (mS/cm)1,6 mS/cm
Plants accommodatedPlants that are already rooted, after rinsing
Rinse before plantingYes
First liquid fertiliserFrom week 4, organic
Values from the French labels and from plagron.com.
Buying guide
Which compost for long-term pot cultivation?
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Frequently asked questions
8 questions
6 key questions, 8 in the detailed view
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