As the Northern Hemisphere moves from Spring to Summer, your gardens will take a huge chunk of time to feed plants, control pests and diseases and generally keep them looking their best.
As my garden takes a rest, I thought I would share some simple, environmentally friendly, but effective homemade, non-toxic fertilizers for the garden using things that most people have around the house.
I’ve used the knowledge that my grandparents passed on to me: one was a keen gardener in inner-city Sydney, who had a double block of land and so was able to feed his family throughout the great depression and strict rationing of WWII, and the other was a farmer on 100,000 acres of land in North Queensland who also had to produce crops during the same tough era.
I’m only including the remedies that I have used and have seen work.
The N-P-K values are indicative only; changing the volume of ingredients or the amount of water used will alter the N-P-K results dramatically, as will the growing conditions of the plants – for instance weeds grown in rich soil will have a higher N-P-K than those grown in poor soil.
N-P-K is the standard Nitrogen-Phosphorous-Potassium ratios that you see on the back of all fertilizer products in the store. Put very simply, Nitrogen promotes leaf growth, Phosphorous promotes root, flower and fruit growth and Potassium promotes overall plant health and disease resistance.
The best way of ensuring your plants aren’t attacked by pests and disease in the first place is to have good soil, with the right plant in the right place and then to ensure that it is adequately watered and fed.
Because that’s not always possible, one of the best ways to give plants a boost is to apply liquid fertilizers. The results are very fast acting.
- Comfrey Tea.
Grab at least 15-20 leaves, tear them loosely & place in a one litre (1/3 gallon) bucket; fill this with water in a shady, out-of-the way corner for at least one month. The bucket should be loosely covered. Stir at least once each week.
Once it has become a horrible, stinking swill, you dilute it between 1:10 to 1:4 (depending on your needs, 1:10 would be for seedlings, pot-plants and newly transplanted plants, 1:4 would be for established trees and shrubs or established, stressed perennials, etc) in a watering can and use it in place of commercial seaweed products.
A 1:10 diluted comfrey tea has an N-P-K value of N 0.02 – P 0.007 – K 0.04.
A 1:4 diluted comfrey tea has an N-P-K value of N 0.08 – P 0.03 – K 0.2.
Compared to a seaweed emulsion, this looks very weak: (A commercial seaweed solution is N 0.1 – P 0.01 – K 1.8) but those products are designed to be used only fortnightly: comfrey tea can be used more regularly. Comfrey is a good solution to promote consistent, continuous flowering and fruit production. Also higher N-P-K values can often be misleading as they are simply leached into the soil and ground-water. A plant can only use so much fertilizer at a time!
- Weed Tea
Made exactly the same way as comfrey tea, only there will be 1:1 weeds to water ratio and, depending on the weeds or other green matter used, Nitrogen values can be much higher, thus promoting leafy growth.
Given how many different weeds there are, I can’t give an N-P-K value for this. Ensure that any weed tea is sufficiently diluted (at least 1:10) to avoid salt and alkaloid build-up (present in many weed species). For gardeners in the UK/Europe, nettles are a great source and can yield an N 0.15 – P 0.05 – K 0.4.
- Molasses Tea
This is a good soil amendment and promotes microbial activity as human grade molasses also contains a lot of other trace elements. Mix 1:10 with hot water. Once cooled gives an N-P-K of 0.7 – 0 – 4.5, so use sparingly. In humid climates it is best applied to the soil as foliar application can promote sooty mould.
- Moss Tea
When diluted 1:10 should yield an N-P-K of 0.06 – 0.01 – 0.06
- Deciduous Oak Leaf Tea
Regardless, oak leaves make the best humus, so plant an Oak tree today 🙂
- Tea Leaves
Reuse the last dregs in the pot by re-filling with boiling water. Once cooled, the N-P-K is 2 – 0.3 – 0.2. Tea is good for grasses and other leafy plants. Tea leaves are also good worked straight into the soil. There is some concern over allelopathic potential with tea and coffee, but I have never seen plants stunted when using tea leaves – especially when used sparingly and in the ground (rather than pot plants).
A favourite of mine as I rarely get through a whole carton of milk before the use-by date. Once your milk is past its use-by-date, mix it 1:1 with water to be used as a foliar spray. Diluted milk has an N-P-K of 0.25 – 0.15 – 0.1 and also provides a quick calcium hit. The microbes that break down the fat and lactic sugars are also great for the soil.
Milk also has other pest and disease benefits, such as controlling aphids, curtailing blossom end rot and has anti-fungicidal properties which help control powdery mildew on plants and other fungal diseases even on lawns.
Despite the many benefits, I would say use milk really sparingly – it smells as it breaks down, and the fungus that grow on leaves and mulches while breaking the milk down aren’t pretty. Additionally too much milk can cause wilted growth, especially in dry summer climates.
And lastly, only full fat milk works!
- Banana skins
This one is probably my favourite as it involves so little preparation. Once you have finished eating a banana, tear the peel into smallish pieces and then place onto the soil around a plant. It breaks down into the soil really quickly, encourages a ton of microbial activity and the N-P-K is 0 – 3 – 42.
All that potassium is a godsend for plant vigour and if you use it around fruiting plants after buds have been set you will increase yield and is good to counter some of the effects of June drop in Apples and Pears.
- Egg shells
Most people swear by crushed egg shells in soil mixes or composts: the N-P-K is approximately 1.0 – 0.4 – 0.1; not especially high, but when egg shells break down they also release calcium carbonate which can counter acidity. However, you would need a lot of egg shells to change soil pH on a permanent basis.
A very ancient tradition is to place a small fish in the panting hole of a tree or shrub. American Indians also used fish heads before sowing corn. Not everyone has whole fish to spare, but any uncooked fish pieces (fins, scales, guts, tails etc) will break down very quickly in the soil and are great for hungry plants like fruit trees and roses. The decomposition encourages substantial microbial activity which benefits the soil. Bury it at least 20cm/6″ to avoid foraging animals!
N-P-K is roughly 6.0 – 4.0 – 0.0. You can substitute for other seafood such as prawns/shrimp, but these have an N-P-K of 2.5 – 10.0 – 0.0, which is more closely aligned to typical commercial bone-meal fertilizers (N-P-K 3.0 – 15.0 – 0.0).
Both fish and shrimp waste takes time to be used by plants, and works best in a neutral to slightly acidic (pH 6.0 – 7.0) soil.
Of course, there are many other home-made fertilizer recipes, but these are ones that I have used. Feel free to share your own!
Happy Gardening 🙂