Planting Around Driveways and Parking

Driveway beds are the hottest planting on most UAE villas, and the heat comes from the paving as much as the sun. This guide explains radiated heat off paving as a stress separate from air temperature, how paving colour changes it, the plants that cope, how to keep planting clear of cars, and how to set out the bed.

Radiated heat from paving

Radiated heat from paving is infrared energy given off by hot stone, concrete or asphalt, and it strikes a plant from below and from the side regardless of air temperature. On a UAE summer afternoon, dark paving at 65C radiates roughly 160 watts per square metre more than a surface at the 45C air temperature would.

That number comes straight from physics. Every surface emits infrared in proportion to the fourth power of its absolute temperature. A surface at 45C emits about 580 watts per square metre. The same surface at 65C emits about 740. Dark paving in direct July sun routinely runs 20 degrees or more above the air, so plants in the first metre beside it take that extra load on every leaf facing the drive.

The load doesn't stop at sunset either. Paving stores heat through the day and gives it back after dark, so a bed beside a driveway stays warmer than the open garden into the night. Plants there lose the cool hours they would normally use to recover, and a species that copes with 45C air in a lawn bed can fail beside a drive.

How paving colour changes the heat

Paving colour decides which kind of heat a bed receives. Dark asphalt and charcoal pavers absorb most of the sunlight and run hottest, so they radiate the most infrared. Light grey or cream pavers stay cooler but reflect more sunlight up into the underside of leaves.

A light paver reflecting about a third of the midday sun sends roughly 300 watts per square metre upward, onto leaf surfaces that normally sit in their own shade. Dark asphalt reflects far less and makes up for it in infrared. Neither is gentle. Sandy beige pavers sit between the two and are the kinder surface next to planting.

Height helps whatever the colour. Both radiated and reflected heat fall off with distance, so a shrub canopy starting 60 cm above the paving takes much less than a groundcover lying flat against the edge.

Plants that cope with heat off paving

Plants that cope beside driveways combine heat tolerant leaves with a habit that keeps foliage off the paving surface. Six species do this reliably in UAE driveway beds, from low mounding succulents to upright shrubs with their canopy held above the hottest layer.

1. Sesuvium portulacastrum, the native sea purslane, is a succulent groundcover that takes both heat and salt.
2. Portulacaria afra stores water in thick leaves and grows as a low, dense mound.
3. Leucophyllum frutescens has silver felted leaves and holds its canopy about 50 cm above the ground.
4. Tecoma stans flowers yellow through summer and grows upright to 2 m.
5. Dodonaea viscosa forms a narrow leaved screen that can be clipped to any height.
6. Lantana montevidensis trails low and flowers through the heat, though its leaves need a 20 cm gap from the paving edge.

Avoid soft leaved groundcovers and lawn grass against the paving edge. The last 30 cm of lawn beside a driveway usually burns brown by July, and the fix is a gravel strip there rather than more water.

Keeping plants clear of cars

Keeping plants clear of cars means three distances: a car door swing of about 1 m on each side of the parking bay, no overhanging branches that drop sap, fruit or flowers onto paint, and no thorny species within reach of anyone getting in or out.

Inside the door swing, plant nothing taller than 40 cm, so doors open over the planting. Keep bougainvillea and Carissa, both thorny, at least 1.5 m from any parking bay. Don't park under Ficus nitida, date palms or Delonix regia, which drop figs, sticky fruit and sap onto cars. Choose shade trees that drop dry leaves, and put the canopy edge beside the car rather than over it.

Root heave is a separate risk to the paving itself. Aggressive rooting trees lift interlock pavers within 3 to 5 years, so a tree bed next to a drive needs a root barrier installed at planting time.

Setting out a driveway bed

A driveway bed works well with a 30 cm gravel strip against the paving, low succulents in the next 50 cm, and taller shrubs at the back. Gravel absorbs the worst of the radiated heat at the edge and keeps soil off the drive after rain or irrigation.

Use a separate drip zone for driveway beds, since they dry faster than the rest of the garden. Edge restraints, kerbs and planting pockets go in most cleanly at the same time as the paving, and the hardscape service can lay the drive, the gravel margin and the bed edges as one job so the levels drain away from the planting.

FAQ

Heat off the paving and clearance from the cars are the two driveway questions that come up before any plant is chosen. The answers below condense the relevant sections into a short form for anyone planting beside a drive or a parking bay.

What tolerates heat off paving?

Sea purslane, Portulacaria, Leucophyllum, Tecoma stans and Dodonaea tolerate heat off paving because their leaves are succulent, silver or narrow and most hold their canopy above the hottest layer. For stock suited to driveway beds, the outdoor plants collection lists each species with its sun needs.

What stays clear of cars?

Plants under 40 cm tall stay clear of car doors, and thornless shrubs placed at least 1.5 m from parking bays stay clear of paint and passengers. Avoid trees that drop sap or fruit, such as Ficus nitida and date palms, anywhere a car parks underneath.