“Does it clean the air? Or help pollinators? Or maybe it’s a good habitat for wildlife?”
Guerrilla gardening is planting in public with purpose. The first thing to consider is what's needed from 'your' new garden and the plants you’ll grow. If your aim is to help the local environment and ecosystems, here are some ways plants can do it!
What I mean when I say...
Plant = when you plant out a whole plant or bulbs
Sow = when you sow the seed for a plant
Here are some suggestions for plants that can support biodiversity. If you can, take some time to research and get to know your local wildlife and what it needs, and find out which native plants that will thrive and help out in your area.
Comfrey ⚘ leaves are great for compost or chop and drop, plant in spring.
Chives ⚘ little spheres of lilac to white flowers. Edible foliage and flowers. Sow in autumn or spring.
Fennel ⚘ produces umbels of little yellow flowers on tall stems. Edible. Sow in spring.
Dill ⚘ umbels of flowers, edible flowers and foliage. Sow in spring.
Also search local wildflowers! Find out more about wildflowers here.
Sunflower (Helianthus annus) ⚘ Sunflower seeds are edible to birds as well as humans. (Illustrated)
Honeysuckle ⚘ climbing, wonderful scented flowers for both pollinators and birds. Plant autumn to spring.
Plants can act as air purifiers and are used by city planners to “clean” urban air; trees are especially good at this.
Silver birch, yew, elder, London plane , silver maple, honey locust, pines, and cypresses. Plant all from autumn to winter.
Make sure you consider how large the tree will ultimately grow!
'Remediative' plants naturally help to extract toxins from the soil.
Sunflower (Helianthus annus) ⚘ Sunflowers are brilliant in so many ways. Bright, big, pollinator-friendly, edible* and soil remediators – they're one of our top picks for guerrilla plants!
Willow ⚘ Salix alba removes pollutants deep in the soil. Can be grown from cuttings stuck in the ground. Plant cuttings in early spring, plant bare root from autumn to winter.
Mustard ⚘ Brassica juncea is super effective and has little yellow flowers that are beautiful and loved by pollinators. Self seeds freely. Sow seed in spring.
*Although each of these plants may usually be edible (or medicinal in the case of willow), if you're using a plant as a soil remediator... don't eat it! It will have absorbed the toxins.
Comfrey ⚘ a dynamic nutrient accumulator, which means its roots plunge deep into the soil and bring up nutrients that are stored in the leaves and eventually rot down into the soil surface. Great for chop and drop to build and protect soil.
Nettles ⚘ high in nitrogen so great for a compost heap or for home fermented plant feeds. Grows from root cuttings. Grow this plant with caution!! it will go rampant if unchecked!
Clover ⚘ fixes nitrogen into the soil. Sow in spring or autumn.
Lupin ⚘ fixes nitrogen into the soil. Sow in spring.
Vetch ⚘ fixes nitrogen into the soil. Sow in spring.
Bare soil is a wound in the Earth. It’s important to protect the soil with ground cover.
Periwinkle ⚘ crawls and climbs, very enthusiastic growers! Pretty white or purple star-like flowers begin in late winter/early spring. Plant autumn-spring.
Mint ⚘ a culinary and medicinal herb, likes some shade and will tolerate damp clay soils. Pollinator plant if allowed to flower. Plant in autumn or spring. Grows from cuttings of areal or root parts.
Clover ⚘ nitrogen fixer, pollinator plant. Sow seed in spring or autumn.
Alpine strawberry ⚘ edible fruits and leaves. Likes the shade. Plant in spring.
Soil compaction means plant roots have to fight harder to get through, leading to poor root growth. It may also prevent water from soaking in deeply to feed the roots.
If you notice rainwater pooling on the surface, or you can just feel that the soil is hard and compact, these plants have root systems that will it break up:
Mustard ⚘ sow in spring.
Alfalfa ⚘ sow in spring.
Fruit trees! Plant them all as bare root from autumn to spring.
Ultimately, the right plants to support your local ecosystem will depend on exactly where you live, but I hope these help as a place to get started!
Illustrations by Sara Jolly.