This summer, we are working with Hozelock to explore whether foliar feeding container grown plants can increase flowering, and the provision of nectar and pollen for bees. For this trial, we are feeding containerised nasturtiums with comfrey and seaweed feeds.
To ensure consistency, we are using commercially available Agralan comfrey tonic and Chase SM4 seaweed extract, but making liquid feeds is a simple and effective way for gardeners to feed potted plants with home grown ingredients.
Seaweed is not readily available to most gardeners, but comfrey and nettles can both be grown in domestic gardens to produce nutrient-rich liquid feeds. The leaves of stinging nettles (Urtica dioica) are particularly high in nitrogen, an important nutrient to plants when they are producing leafy growth. Comfrey is high in potassium, which is used by plants as they develop flowers and fruit. There are many different species and cultivars of comfrey, but Russian comfrey (Symphytum x uplandicum) ‘Bocking 14’ is normally recommended, as it was identified as the most potassium-rich variety by Garden Organic founder Lawrence Hills.
To make nettle or comfrey liquid feed, you will need: a patch of nettles or comfrey, shears or other cutters, a bucket or similar container (preferably with a lid), water and you’ll need to wear gloves.
- From mid to late spring, once plants reach a height of 30cm, cut them down to around 5cm above ground level (this can be repeated several times in a season, each time the plants re-grow).
- Roughly chop the leaves and pack them tightly into the container, filling it completely.
- Add water so that it covers all of the leaves. As the leaves rot, there can be quite a pungent smell, so it is a good idea to cover the container.
- Let the leaves steep for a minimum of 4-6 weeks depending on the time of year/temperature.
- Strain the liquid from the leaves. The sludgy leaves can be added to the compost heap.
The resulting liquid feeds can be used neat or diluted, depending on the needs of individual plants and how frequently they will be fed. They can either be watered into the growing media or sprayed onto the plant leaves as a foliar feed; see our blog about using liquid feeds. Liquid feeds are not usually applied to plants that are growing directly in the ground as unlike potted plants, they should have access to all the nutrients they need and it is preferable to feed the soil rather than the plant.
To feed the plants in our trial, we are using Hozelock’s Pure sprayer which is designed for the application of natural products and homemade solutions, and comes with a filling filter so that small fragments such as pieces of comfrey leaf do not cause blockages. We gave our nasturtiums their first feed last week and are keen to see what differences there might be between the various treatments.