There's no one-size-fits-all when it comes to what plants are "best" – it's about picking plants that fit your guerrilla plot's unique conditions. In this guide, ecological grower and guerrilla gardener Poppy Okotcha breaks down how to choose the best plants for your guerrilla gardening site.
What are the best plants for guerrilla gardening?
New guerrilla gardeners often want to know the best plants to guerrilla garden with. But one guerrilla's perfect plant is another's nightmare! Sunflowers (a symbol of guerrilla gardening) won't work if you have a shady site; nasturtiums (one of my favourites, which are very low maintenance, edible, and pollinator-friendly) are invasive in some areas.
The best plants for guerrilla gardening are the ones that best suit your conditions, taking into account seasonal temperatures, daylight hours, shade, soil type, and so on, as well as your intention for your garden. Don't feel daunted! Knowing these factors is straightforward, and actually makes decisions much less overwhelming (it narrows the choice of plants down from, well, every species in the world to a manageable list).
The guide below breaks down the factors that inform which plants are best for your guerrilla garden. I’ll share some examples of plants that would suit various conditions, but please bear in mind these won’t work for every set of circumstances, regional ecosystem, or climate! Consider your site's features as a whole, and always avoid planting anything invasive in your area.
Soil
The soil is the foundation of what you can grow. All gardeners should be aware of their soil's pH and texture. Guerrilla gardeners also need to deal with a whole host of occupational hazards when it comes to soil, from pollutants to extreme (trampling-induced) compaction.
If you're creating guerrilla planters, you'll be able to add your own soil in, meaning you can control these conditions and not worry about matching plants to existing soil.
pH
pH is the measure of your soil’s acidity or alkalinity. Generally, plants like slightly acidic to neutral soil (6–7 on the pH scale), but urban soil can skew alkaline due to building materials and processes: cement, mortar, and limestone are alkaline. You can get basic pH testing kits from many garden centres and DIY stores for under £5 ($6).
Plants for brownfield sites
If you're guerrilla gardening a brownfield site (a spot where a building once was) the best plants will be alkaline-tolerant plants – marigolds, lilacs, and wild marjoram are examples.
Texture
Soil texture is determined by its mineral composition: the ratio of clay, silt, and sand within it. To find out your soil's texture, check out our 3 easy ways to test soil (no apparatus needed).
Plants for sandy soil
These plants need to be fairly drought-tolerant, such as lavender, verbena, and root vegetables.
Plants for clay soil
In clay soil, plants need to survive being waterlogged and cold. Roses and foxgloves love clay!
Plants for silty soil
Try planting grasses, shrubs, and climbers like Rosa canina (wild dog rose).
Problems
A lot of guerrilla gardening is done in nutrient-depleted, compacted, polluted soil. If you have any of these problems (or all of them!) try adding remediative plants, dynamic nutrient accumulators, or nitrogen fixers. Bear in mind, although each of these plants may usually be edible (or medicinal), if you're planting in polluted or toxic soil, don't eat them! They may have absorbed the toxins.
Polluted soil
'Remediative' plants naturally help to extract toxins from the soil. These include sunflowers, willow (Salix alba), and mustard (Brassica juncea). Mustard is super effective and its pretty yellow flowers are loved by pollinators. Once planted, it self seeds freely.
Infertile soil
If you're starting out with infertile soil, you can go straight in with low-maintenance plants that thrive on being left alone, like yarrow and nasturtiums. You could also set the stage for future plants by choosing plants that will restore fertility:
Dynamic nutrient accumulators, like comfrey, have deep roots that plunge into the soil and bring up nutrients to the leaves, which (when they fall and rot) eventually return these nutrients into the soil surface.
Nitrogen fixers, like clover, lupin, and vetch, have nodes on their roots that convert nitrogen (a key plant nutrient) in the air into a form that plants can absorb.
Compacted soil
It's hard to get a garden started when the soil feels like concrete. While you can get hard at work with a garden fork to break up soil compaction, you could also let nature do the work! Sow seeds which will develop strong, deep root systems that can break up compacted soil, such as mustard, alfalfa, or potatoes.
Shallow soil
City soil is sometimes laid on top of hard surfacing, rather than running deep into the earth. Luckily, various plants don't need a deep root system to thrive, including chamomile, bee balm, and creeping thyme (which will also tolerate some light trampling).
Light
Different plants require different light levels – if you plant a sunflower in a dark spot it won’t be happy, and you’ll be able to tell! To check the light in a space, first find out the orientation of your site. Where are north, south, east and west? Try using the compass function on your phone or on maps. If you’re happy to invest a bit of money, try the app “Sunseeker”, which will tell you where the sun is in the sky at different times of the year! North of the equator, south-facing gardens get the most sun.
Then, identify any obstacles that might cast shade. Are there any walls, trees or buildings in the way? If you have time, visit your site at different times of day (and throughout the year) to see how the light changes. Here's some hypothetical situations, and how it might affect the light:
A big building to the south of your chosen patch would block a great deal of direct sunlight.
A high wall along the west side would be blocking out the afternoon sun. Afternoon sun is warmer and more intense than the morning sun.
A great big evergreen tree will cast shade bellow it all year round, while a deciduous tree (one that loses its leaves in autumn) will cast seasonal shade. Notice if the shade below the tree is dark or dappled.
Sunny spots
Plants need light, but too much can scorch certain kinds. For very sunny spots, try sunflowers, calendula, chamomile, or mediterranean herbs.
Shady spots
Shade-loving plants are those that, for instance, adapted to woodland undergrowth, like bluebells, woodruff, and blackberries.
Water
If your chosen site is very shady it’s likely it could be wetter than if it were in the sun. Take a look at the soil, is it very damp or is it dry? Can you spot a water source like a broken gutter or rainwater overflow pipe? Is the spot at the bottom of a slope or hill? How often will you be able to water your guerrilla garden?
Drought-tolerant plants
These plants are used to drier climates, such as mediterranean herbs (like thyme, lavender, or rosemary) or California poppies.
Damp loving plants
Plants such as wild garlic and rhubarb, that thrive in wetter conditions and climates.
Weather
Seasons
How cold does your area get in winter? How hot in summer? This dictates how “hardy” your chosen plants need to be. Hardiness is a measure of how well a plant can survive extreme climatic conditions. In the UK, “hardy” plants are those that can survive cold winters; in arid climates, the term refers to plants that can withstand heat and drought. While areas of more extreme temperatures need “hardy” plants, milder climates can accommodate what is known as “tender” plants.
In the UK, the Royal Horticultural Society (RHS) has a plant hardiness rating system, which categorises plants from level H1 (plants that need to be kept in a heated greenhouse) to H7 (very hardy plants). To find out how hardy your chosen plants need to be, search the average minimum winter temperature where you live, and compare this to each RHS plant hardiness category.
Americans can use the United States Department of Agriculture (USDA) hardiness zone map. For other countries around the world, simply find out your area's seasonal temperatures and use either of these systems to work out your relevant hardiness zone.
Hardy plants
Taking the UK definition (plants that can survive frost), hardy plants include dogwood (Cornus alba ‘Sibirica’), heather (Calluna vulgaris), and Swiss chard.
Wind
If you can, try to take note of how exposed your spot is. If your spot is sheltered, you don't need to worry, but if it's windy you'll need plants that can weather it.
Wind-resistant plants
Many plants that grow on clifftops, like gorse (Ulex) and plants used to open fields (including various wildflowers, like oxeye daisies, ragged robin and red campion) are adapted to resisting the force of wind.
Site type
The type of space you're working with will also make an impact.
Tree beds
Choose low-growing, shallow rooting plants with low water-demand, so they’re not competing with the tree (especially if its a young tree). You'll also need to choose shade-tolerant plants. Spring bulbs found in woodlands like bluebells and wild garlic work great bellow deciduous trees, taking advantage of the spring sunshine before the tree has leaves.
Plants for tree beds
Spring bulbs (e.g. daffodils), herbaceous perennials (e.g. wood anemone), annual wildflowers (e.g. common poppies).
Roadside
Gasses dust and grime can affect the plant’s ability to “breathe”. Some plants are more tolerant of pollution than others. Notice where your site is located: is it beside a busy road, factory, or airport for example?
Pollution-tolerant plants
Butterfly bush (Buddleja), honeysuckle, and berberis.
Cracks and crevices
Have you ever smiled at a plant growing defiantly out of the side of a wall? Some plants are suited to growing on vertical stone, like alpine and coastal species, and others have adapted to urban brick walls.
Plants for walls
Mexican fleabane, stonecrop, common harebell (Campanula rotundifolia).
If this whistle-stop introduction to how to choose the best plants for your site has got you excited to get guerrilla gardening, you can find much more detail and many more useful suggestions in the handbook Get Guerrilla Gardening.
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