Eggshells don't have to be thrown away, they can serve as a source of nutrients for plants. We explain how to use eggshells as fertilizer.
On average, a German citizen eats 245 eggs a year. The resulting eggshells usually end up in the organic waste. However, some resourceful gardeners appreciate the pods as fertilizer. We explain to you what effects eggshells can have and how exactly they should be used.
contents
- How do eggshells work as fertilizer?
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Use of eggshells as fertilizer
- Egg shells on the compost heap
- Which plants can be fertilized with eggshells?
After introducing the ingredients and their effects, this article will explain the correct use of eggshells. It is also important that only the right plants are fertilized with them. Therefore, the last paragraph presents a selection of suitable garden plants.
How do eggshells work as fertilizer?
Eggshells consist of 90 to 95% calcium carbonate (CaCO
3), which is also called "carbonate of lime". Lime is suitable for increasing or stabilizing the soil pH value, but the effect of eggshells only unfolds very slowly. To dissolve the lime, carbonic acid (HCO3–), which is caused by the breathing of the plant roots. With the help of carbon dioxide, the compound Ca (HCO3–)2which in turn is converted into the calcium ion Ca2+ , Carbon and water rise - during this process the pH value rises. Unfortunately, this is not the case with clay-rich soils, as these are chemically too stable to be influenced by the slow-acting lime application.Tip: Heavy soils are better treated with quicklime or slaked lime if the pH value needs to be raised. For example, untreated wood ash contains quicklime. More detailed information on how to use Wood ash as fertilizer you can read about it in our special article. Always test the pH of your soil before applying lime.
The calcium ions released in the reaction with carbonic acid (approx2+) are essential when cementing soil particles. They create the connection between clay minerals and humus molecules and thus ensure stable crumbs that promote plant growth in many ways. And of course the released calcium is an essential nutrient element for plants: it serves cell wall stabilization and as a signal ion that is involved in the opening of the stomata is.
In addition to calcium, the nutritional elements potassium, phosphorus and magnesium are also contained in small quantities. Overall, the amounts of eggshells in the household are so small that using them as fertilizer is only worthwhile in some cases, as you will learn in the following paragraph.
Summary: How do eggshells work as fertilizer?
- Eggshells are mainly made of calcium carbonate
- Calcium carbonate can slowly raise the soil pH
- The pH effect is limited to light, less clayey soils
- Calcium ions released are valuable cement of soil particles and, together with humus and clay minerals, can improve the soil structure
- Calcium is one of the essential nutrients for plants
Since eggshells almost only provide calcium, they cannot be used for fertilization on their own. We therefore recommend an organic long-term fertilizer for the supply of your plants: This promotes the build-up of humus molecules, which in connection with Ca2+ become stable crumbs. Our Plantura organic fertilizer are such organic long-term fertilizers that even do not contain any animal components.
Use of eggshells as fertilizer
Eggshells are suitable for bringing in calcium, increasing the pH value and cementing soil particles. However, absolute calcium deficiencies and very low pH values are rare in German gardens; they occur, for example, on former bog areas. In peat-based potting soil, problems with calcium and the pH value can occur more frequently, because peat is very low in calcium. If peat-containing potting soil is introduced into the bed in large quantities, a lack of lime can occur in the plants growing there after a long period of time. This is especially true in planters, in which the volume is limited and there is no connection to the calcareous, natural soil. All lime-loving plants are of course particularly susceptible to this. In vegetable patches with lime-loving varieties and planters, the application of eggshells makes sense. The large-scale distribution on lawns or beds, on the other hand, is rather ineffective due to the small amount alone.
On light soils and beds that have been improved with peat soil, you can get about 100 every three to four years Spread out up to 200 grams of eggshells per square meter - if the pH value can be proven to be too low is. In any case, you should check this beforehand with the help of a pH test so as not to influence the pH value to a level that is harmful to plants. Basically, the effect of eggshells is greatly improved when they are finely ground. By increasing the surface, the calcium carbonate dissolves more quickly. Incidentally, this depends on the availability of sufficient water for the solution, which is why it can be applied together with water.
Tip: Grind the eggshells in a mortar or pound them in a tea towel. You can then let the resulting powder infuse for a day in a can with rainwater. When applying, however, you should make sure that you only wet the soil and not the plants - otherwise there will be unsightly limescale stains. When applying lime, you should wear gloves if possible, as the high pH value attacks the skin.
Please note: Calcium carbonate and egg shells should never be distributed in connection with ammonium or phosphates. Therefore, take a break of at least three months between the distribution of fertilizers containing ammonium or phosphates and eggshells. Contact between calcium and ammonium produces gaseous, smelly ammonia. Calcium and phosphate together form poorly soluble calcium phosphates, making both nutrients inaccessible to plants.
Egg shells on the compost heap
Another possible application of eggshells is distribution on the compost heap. A high pH value stimulates the activity of bacterial soil dwellers and can thus accelerate composting. If the small composters are too active, however, the volume of the compost can be lower. Eggshells should therefore only end up in the compost in connection with acidic material - such as rhododendron cuttings, bog plants, peat soils, coniferous wood or oak leaves. A fine dusting of this material with ground eggshells is sufficient.
Summary: Using eggshells as fertilizer
- The calcium carbonate in eggshells can be used to increase the pH value of acidic soils - but these are quite rare in Germany
- It can be used more often in beds that have been improved with peat soil or in potted plants in peat-based potting soil
- In any case, before distributing it, you should do a pH test of the soil
- When finely ground and mixed with water, the calcium carbonate in the eggshell works the fastest
- You must never distribute calcium carbonate in connection with ammonium or phosphates
- Eggshells on the compost heap can compensate for the low pH value of acidic rotting material
Which plants can be fertilized with eggshells?
Lime-loving plants in beds and pots thank you for a supply of finely ground eggshells. The following table shows a selection of lime-loving garden plants. You can find some more lime-loving specimens in our article on fertilizing with ash.
| Lime-loving trees | Lime-loving vegetables | Lime-loving perennials |
|---|---|---|
| Roses (pink) | All types of cabbage (Brassica) | Columbine (Aquilegia) |
| Blackberries and raspberries (Rubus fruticosus/R. idaeus) | Carrots (Daucus carota subsp. sativus) | Creeping Gunsel (Ajuga reptans) |
| Common rock pear (Amelanchier ovalis) |
Rhubarb (Rheum x hybridum) | Common hazel root (Asarum europaeum) |
| Barberries (Berberis) | Chicory salad (Cichorium) | Asters (aster) |
| Butterfly lilac (Buddleja davidii) | Asparagus (Asparagus officinalis) | Blue fescue (Festuca cinerea) |
| Boxwood (Buxus sempervirens) | Garlic (Allium sativum) | Small grape hyacinth (Muscari botryoides) |
| Peonies (Paeonia i. S.) | Tomatoes (Solanom lycopersicum) | Little Snowdrop (Galanthus nivalis) |
| Currants (Ribes) | Onions (Allium cepa) | Cyclamen (Cyclamen) |
| Spirals (Spiraea) | Celery (Apium graveolens) | Autumn Timeless (Colchicum autumnale) |
| Elderberry (Sambuccus) | Leek (Allium porrum var. Porrum) | Star ball leek and giant leek (Allium chrisophii, A. giganteum) |
| Fruit trees | Beets (Beta vulgaris) | Steppe sage (Salvia nemorosa) |
| And many more | And many more | And many more |
More information about Natural fertilizers can be found in our special article.
However, eggshells alone cannot fully meet the nutritional needs of most plants. We therefore recommend using an organic long-term fertilizer to help. Our Plantura organic fertilizer ensure long-term and natural for strong and healthy plants and thus ideally complement fertilization with eggshells.
