Roots normally grow down, so seeing some above the soil can feel alarming. Usually, though, it’s a plant reacting sensibly to its surroundings rather than a sign of disease. The cause often depends on what kind of plant you have: a climbing houseplant, a crowded potted plant, and an old yard tree come up for different reasons. The useful question is whether your plant is doing what it’s built to do, or telling you something about its soil or pot.
Some Plants Are Built to Grow Roots in the Air
Many popular houseplants, including pothos, philodendron, anthurium and monstera, come from tropical forests where they climb trees. They grow aerial roots, which are roots that sprout from the stem into open air, to grip supports and gather water. In monstera relatives, aerial roots can take over so fully that the base of the stem dies and the aerial roots alone link the plant to the soil.1The New Phytologist. Hydraulic architecture of Monstera acuminata: evolutionary consequences of the hemiepiphytic growth form On a pothos aerial root, the side touching a support keeps taking up water, while the side facing the air seals itself to limit water loss.2PubMed Central. Sclerified Cork Outperforms the Exodermis: Root Water Permeability Decreases in the Soil‐To‐Canopy Transition of the Aroid Vine Epipremnum aureum
Telling these apart from roots escaping the pot is simple. Aerial roots sprout from stem joints above the soil, often near leaves, and are usually firm, brown or green, and thicker than soil roots. Escaping roots come up from the soil or out of drainage holes.
Aerial roots also feed the plant. In pothos, philodendron and anthurium, they took up nitrogen better than the plant’s soil roots did.3PubMed Central. Aerial roots elevate indoor plant health: Physiological and morphological responses of three high-humidity adapted Araceae species to indoor humidity levels All three grew more in high humidity, with aerial roots showing the biggest gains.4PubMed Central. Aerial roots elevate indoor plant health: Physiological and morphological responses of three high-humidity adapted Araceae species to indoor humidity levels
Leaving them alone is fine. If you’d like to give them a job, guide them onto a moss pole or tuck them into the soil. A moss pole or bark slab imitates the tree trunk a climber would grip in the wild, so roots that reach it can anchor and take up moisture. Watering the pole along with the plant keeps it attractive to the roots. Misting or a humid spot keeps aerial roots plump and useful. If a few look untidy, trimming them with clean scissors won’t harm the plant.
Not every plant with roots in the air is a climber. Some orchids grow roots that run through open air and are meant to be exposed to it. These roots are often silvery when dry and turn greener after watering, so a silvery root isn’t dead. Burying them in dense soil can suffocate them, which is why they’re usually left above the mix.
Outdoor plants show the same habit. Strangler figs start high in a host tree, living on air and rain, and send roots down to the ground.5Princeton Nature Notes. Strangler Figs: Airborne Roots and Flying Buttresses Once those roots reach soil, the fig’s growth speeds up.6Princeton Nature Notes. Strangler Figs: Airborne Roots and Flying Buttresses Some mangroves send up snorkel-like roots from mud to breathe in waterlogged ground.7PubMed. Adaptive roots of mangrove Avicennia marina: Structure and gene expressions analyses of pneumatophores
Waterlogged Soil Pushes Roots Toward the Surface
Roots need air as well as water, and soil that stays saturated squeezes out the air they breathe. Root cells use oxygen to release the energy they need for growth and for pulling in water and minerals. Water fills the pore spaces that normally hold air, and oxygen moves through water far more slowly than through air.
The plant responds. Waterlogged plants build up growth hormones that together set off new roots from the stem.8PubMed. Waterlogging-induced adventitious root formation in cucumber is regulated by ethylene and auxin through reactive oxygen species signalling These emergency roots from the stem appear right where soil meets air.9bioRxiv. Adventitious roots facilitate surface water uptake but only partially sustain transpiration under waterlogging in tomato (Solanum lycopersicum) In waterlogged tomato plants, water use dropped by up to about half within two weeks, then partly recovered as surface roots appeared.10bioRxiv. Adventitious roots facilitate surface water uptake but only partially sustain transpiration under waterlogging in tomato (Solanum lycopersicum)
Roots without oxygen can’t take up water well, so a plant can wilt even in wet soil. That’s why overwatering can look like underwatering, and why owners often add more water when the plant needs less.
If roots sit wet too long, they can rot. Watch for slowed growth, yellowing leaves and wilting even when the soil is moist.11Epic Gardening. Root Rot: How to Identify, Treat, and Prevent it Larger plants may drop leaves out of season.12Epic Gardening. Root Rot: How to Identify, Treat, and Prevent it
To check, push a finger 5 cm into the soil a day after watering; still soggy means too wet. Lift the pot too: an unusually heavy one after days without water points to poor drainage. A sour smell or dark, mushy roots at the drainage holes are further clues, and surface roots plus yellow lower leaves can point to overwatering.
To fix it, water only when the top few centimetres are dry, use a pot with drainage holes, and empty saucers after watering. If water still pools, repot in a looser, faster-draining mix, trimming brown, mushy roots and keeping the healthy white ones.
Hard or Compacted Soil Turns Roots Sideways
Roots normally grow down because they sense gravity and grow faster on their upper side.13Wikipedia. Gravitropism When a root hits a compacted layer, it can push through, turn sideways, or stop growing.14PubMed Central. Soil compaction and the architectural plasticity of root systems Roots too thin to break through get deflected horizontally and spread near the surface.15PubMed Central. Soil compaction and the architectural plasticity of root systems
Roots in dense ground aren’t simply stuck. Compaction squeezes the air spaces in soil, so they face both resistance and low oxygen. Staying near the surface lets them reach the loosest soil, which often still has some air and moisture. The top layer is also often the richest place to grow: decaying leaves and roots make it hold more water and nutrients.16USGA. Why Are My Plant Roots Growing Above Soil? The tradeoff is that shallow roots dry out more quickly in hot spells, so these plants may need watering more often than deep-rooted ones.
In a yard or bed, compaction shows up when water puddles or runs off instead of soaking in, or when a screwdriver or trowel is hard to push into moist soil. Foot traffic paths, driveways and new-build lots are common culprits, and roots often fan out in a flat mat just under or at the surface.
To loosen things up without hurting roots, add 5 to 8 cm of mulch over the root area, keeping it off the trunk. Reduce foot and vehicle traffic over roots, and try core aeration on lawns so air and water reach deeper. Avoid digging or tilling deep near established tree roots.
Crowded Pots and Planting Depth
A root-bound plant has filled its pot so completely that roots circle and have nowhere to go. Roots then poke up from the soil surface and out of drainage holes.
The leaves can look fine for a while, because roots circling the inside of a pot form a dense mat that hides the problem. A plant that dries out unusually quickly after watering may have more root than soil in the pot. Sliding it out is the surest check: a healthy rootball holds together and shows white or pale roots running through the soil. Other signs it’s time to repot: water rushes straight through without soaking in, growth stalls even with regular feeding, or the pot tips over or bulges from root pressure.
For repotting, water a day before so the rootball slides out easily. Gently tease apart circling roots, cutting any that wrap tightly. Move up only one pot size, about 2 to 5 cm wider, and set the plant at the same depth it grew before, firming the mix lightly.
Depth matters too. When a stem is buried deeper than before, trees grow a new set of roots along the buried stem up to the soil surface.17Journal of Environmental Horticulture. Planting Depth in Containers Affects Root Form and Tree Quality New roots near the top of a buried stem can therefore mean the plant was set too low.
Exposed Tree Roots in the Lawn
Each year a tree’s roots get thicker, like the trunk, and eventually they can break through into the lawn.18Wisconsin Horticulture. How to Deal with Surface Tree Roots Erosion of soil over a root system also exposes roots.19Wisconsin Horticulture. How to Deal with Surface Tree Roots Heavy rains, especially summer storms, can wash away topsoil and leave roots bare.20Absolute Tree Service. Exposed Tree Roots: The (Not So) Hidden Danger in Your NoVA Yard Most tree roots live in the top 30 to 45 cm of soil, so surfacing roots are common, and shallow-rooted trees such as maples and willows show them more than others.
In a forest, roots are covered by leaf litter and left alone. A lawn is mowed and walked on, so exposed roots become obvious. Mowers can scalp grass and hit roots, which is why a root-studded lawn is hard to maintain. The roots themselves usually don’t mean the tree is dying, only that it has been growing for years.
Grass struggles over them for its own reasons. Tree roots compete with grass for water and nutrients, and the tree usually wins because its roots are larger and well established. Dense shade limits the light grass needs, and frequent mowing and foot traffic add stress.
Several well-meant fixes backfire. Don’t cut large roots, which can weaken the tree and make it unstable. Don’t pile thick new soil over roots, which can smother them, and don’t mow over them, since scraping the bark opens wounds to disease. Call an arborist before removing any root thicker than a few centimetres.
Safer options: spread 5 to 8 cm of wood mulch over the root zone, or plant shade-tolerant groundcovers instead of lawn. If you’re reseeding grass, add no more than about 2 to 3 cm of soil at a time. Redirecting gutters and slopes that wash soil away keeps the problem from returning.
When Above-Ground Roots Mean Trouble
Firm, pale or brown roots on a plant with healthy new leaves are usually harmless. Slowed growth, yellowing and wilting alongside surface roots suggest the roots can’t take up enough water and nutrients.21Epic Gardening. Root Rot: How to Identify, Treat, and Prevent it
A quick check sorts the two. Pinch a root: firm usually means healthy, while mushy or hollow suggests rot. For trees, look for dieback in the crown or a lean.
Look at the rest of the plant before blaming the roots. New growth is the best sign of health, because a plant with failing roots usually stops producing new leaves first. Leaves that yellow from the bottom upward suggest a root or watering problem, while crispy brown edges point more toward dry air or underwatering than rot.
Some situations need help. A tree leaning more than before, or with cracked soil at its base, needs an arborist. Rot spreading through most roots of a houseplant may mean taking cuttings to save it. Repeated waterlogging in a bed may need drainage work, and bare roots on a slope often need erosion control.