If you are a polytunnel owner looking for ways to go greener, you may be looking for tips to help you in your efforts to garden organically. Organic gardening involves understanding that sustainable systems are the key to continued productivity. It is important to take steps to ensure that your soil is healthy, and that the crops you grow get the nutrients that they need, not just in the short term but over time. Good gardening practices such as mulching, creating polycultures and crop rotation can all help to maintain the natural cycles on your farm or in your garden. But another way to feed the plants is through using liquid plant feeds.
If you are an organic gardener then creating and using home- made plant feeds is one of the methods you can use to ensure that your plants and your soil remain happy and healthy. You can make organic plant food from materials you are likely to already have access to in your organic garden or in the natural environment close to your home.
Liquid Plant Feed Ideas
There are a range of different liquid plant feeds that can be created quickly and easily for use in your organic garden or on your permaculture farm. Some common liquid plant feed ideas are included below:
– Compost Teas
If you are already making a good quality compost at home, you can use some of that compost to make one of the quickest and easiest natural plant fertilizers imaginable. Simply add a good shovelful of good compost to water, strain the resulting liquid and use it on your vegetable patch.
(You could also consider soaking charcoal in compost tea to create fertility boosting biochar, which is also excellent for carbon sequestration.Biochar could be a useful soil enhancer for your polytunnel – and you may even be able to consider making your own from materials that you can find in your home and on your land.)
If you keep livestock or live rurally and have access to farm manure then you can use these manures in a number of different ways to enrich your soil. One such way is to make a liquid feed from the composted manure. You can use the manure of a number of different creatures to create this liquid gold. If you have pets, you may be able to compost their waste for this purpose. If you keep fish, old aquarium water also makes a great liquid feed, as the fish waste will help your plants to grow.
Another variation on compost tea is to use the liquid found at the bottom of a wormery, in which worms turn your household scraps into good quality worm-castings and composted materials. The liquid drained off from the bottom of a wormery is a great food for plants and you can even make the wormery yourself. Vermiculture, the practice of keeping worms to aid in composting food scraps and other waste, can be a great idea for many organic farms and gardens.
– Plant-Based Liquid Feeds
Comfrey is a plant that is extremely useful to the organic gardener in a number of different ways. All organic gardeners should have a comfrey patch in their gardens. Comfrey leaves decomposed in water make a liquid feed comparable in nutrition to commercial feeds.
Green tea is another option for a liquid feed, which is high in nitrogen and other nutrients. All liquid feeds are often called ‘teas’ but actual tea can be an option, especially if this is a plant that grows well where you live.
Nettles are a common weed that, if handled carefully, can be a real boon to any organic gardener. Nettles can be used to make a nitrogen rich garden fertilizer for leafy plants. Simply allow nettles to rot down in water to make a nutritious liquid feed for nitrogen-hungry plants.
But nettles are not the only plant usually considered to be a weed which can be used in this way. You can also use the same idea to make use of many common weeds plucked from your vegetable beds or other growing areas. This is a way to return their nutrients to the soil without risking spreading them by putting them in your compost.
If you live by the sea or ocean then seaweed is another valuable natural resource. Seaweed can also be used to make a home-made plant fertilizer. Since seaweed is rich in both potassium and trace elements, it can be great for the overall health of your soil as well as for various crops.
Potash Liquid Feed
Wood ash is a great source of potassium and can be great for fruiting plants. Unfortunately, if you make a liquid feed with wood ash and water alone then the result would be strongly alkaline. Still, if the soil where you live is very acidic then a wood ash liquid feed could be one way to help redress the balance and bring the soil to a more neutral pH.
Fish/ Meat Based Liquid Feeds
Though vegetarians will be likely to want to steer clear of this one, if you eat fish you can make your own fish fertilizer using the waste by-products of the fish that you eat or whole fish if you have them available and going to waste. Blending waste and adding water can allow you to use fishy waste as a liquid feed.
If your garden is short of phosphorus then you may want to create a fertiliser that contains plenty of this important nutrient. Meat eaters can use the ground bones from meat meals to make their own bone meal fertiliser, which can also be blended with water and applied to the garden in liquid form.
A bokashi bin system can be used to ferment meat, dairy and fish along with other kitchen waste and to create a nutrient rich tea which can be used to feed your crops, as well as a stable soil-builder that can be added to your regular compost heap or bin.
Choosing and Using Liquid Plant Feed
Whichever liquid plant feeds you choose to use, it is important to choose the right option for different plants and different growing areas. A liquid feed can give plants a boost – but choosing the wrong one can be detrimental, or even kill plants. Consider what plants and soil need, and always err on the side of caution when deciding how strong a solution to use, and you should not go too far wrong when using liquid plant feeds in your organic growing efforts.
The balance of NPK (nitrogen, phosphorus, potassium) in your liquid plant feeds can be shown as a ratio. For a general purpose plant feed, you want the quantities of each of these three to be fairly balanced. Compost teas, manure teas, comfrey tea and seaweed liquid feeds, for example, can all provide a good balance of all these important nutrients. However, there will be times when you may want to tip the balance, and use liquid feeds that are rich in one of the three main nutrients.
When To Use Nitrogen Rich Plant Feeds
One thing to remember, as a general rule of thumb, is that nitrogen promotes leafy growth. Liquid feeds made with plant material, such as nettle liquid feed, or green tea, are ideal for nitrogen hungry leafy plants, or for fruiting or flowering plants early on in their development, when you want to encourage leafy growth.
When To Use Potassium Rich Liquid Feeds
Comfrey tea, compost and manure teas, and, of course, wood ash based plant feeds are all excellent choices for many plants, especially once they reach the stage of flowering or fruit production. Possassium plants an important role through a plant’s life-cycle, in a number of processes including water transportation. It is especially crucial in the growth and reproduction stages.
When To Use Phosphorus Rich Liquid Feeds
Phosphorus is largely responsible for root growth, and flower and fruit production. A meat or fish based liquid feed is a good idea for young plants, to encourage healthy root formation, and also can be beneficial when fed to flowering or fruiting plants, encouraging the number of blooms. You may also wish to use phosphorus rich feeds if you know or suspect that your soil has a phosphorus shortage.
Take care, when making your own liquid feeds, not to make them too strong. Too much of the key nutrients can sometimes be as bad as too little. Too much nitrogen, for example, can scorch or even kill your plants, or encourage leafy growth at the expense of flowers or fruit.
To learn more about protecting the soil ecosystem in your polytunnel and ensuring good levels of fertility for polytunnel plants, check out our other articles and guides. If you have any favourite liquid feed recipes for your plants, please do share these in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.