How to Grow Ashoka Tree (Polyalthia) for a Narrow Green Screen
The tall, pencil-thin “ashoka” lining driveways from Karachi to Delhi is not the ashoka of old medical books. It is Polyalthia longifolia, the false ashoka or mast tree. If your question is how to grow ashoka tree as a green screen, this is the one you want: easy, upright, slow at first, and polite to walls when planted with a little room.
At a glance
- Which tree: Polyalthia longifolia (column ashoka, false ashoka, debdaru)
- Shape: a narrow evergreen column; a weeping form hangs its branches straight down
- Spacing in a row: about 1.5 to 2 m apart for a screen
- Distance: 2 to 3 m from the house wall, 1.5 m from a boundary wall or drain
- Planting months: February to March, or July to September
- Sun: full sun to light shade
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Is this the same ashoka used for medicine?
No, and the mix-up matters. The ashoka of Ayurvedic and Unani tradition is Saraca asoca, a spreading tree with orange-red flower clusters, rarely planted in Pakistani gardens. Polyalthia has drooping, wavy leaves and dull green star flowers. Its bark is sometimes sold in place of the real thing. If you came here about bark for periods, read ashoka bark, real vs fake. This page is only about growing the column tree.
Is the ashoka tree right for my plot and city?
It is the classic answer for a small front lawn because it grows up, not out. It handles Karachi humidity, Lahore heat and Delhi winters well. Very hot, dry Multan and Sukkur summers scorch young leaves unless you water steadily, and hard frost in Islamabad browns the tips of young plants.
| Use | Verdict | Reason |
|---|---|---|
| Privacy row along a boundary wall | Plant | Narrow, evergreen, tidy |
| 5 marla front lawn | Plant | One or two fit where a spreading tree would not |
| Shade for a car or sitting area | Skip | The column casts little shade; choose Sukh Chain |
| Hot dry towns without summer water | Maybe | Survives, but looks thin and scorched |
| Right against a wall or under wires | Skip | Roots near footings, crown into wires |
For wide shade, see our guide to growing Sukh Chain.
Seed or sapling: which is better?
Buy saplings for a hedge row; they are cheap and uniform. Seed is fine for patient gardeners. The weeping (pendula) form is usually sold as a nursery plant; check the label, because the shape is fixed in the young plant.
How to grow ashoka tree from seed
- Collect ripe fruits when they turn dark purple to black in early summer. Birds take them quickly.
- Rub off the pulp in water and wash the seed clean.
- Sow at once. The seed loses viability if stored long.
- Sow 1 to 2 cm deep in bags of 2 parts soil, 1 part compost, 1 part sand.
- Keep warm, shaded and damp. Germination is slow and uneven; some seeds take a month or more.
- Grow the seedling in a 10 to 15 litre pot for one to two years before planting out.
How do you plant an ashoka row?
- Mark a line about 1.5 m from the boundary wall.
- Dig pits 45 to 60 cm wide and deep, about 1.5 to 2 m apart.
- Mix topsoil with compost or old manure, one basket per pit.
- Plant at the same depth as in the bag and firm the soil.
- Water each pit slowly until soaked; stake tall saplings against wind.
Buy in pairs, plant one spare
Rows look wrong when one plant dies in the first summer and its replacement is half the height. Buy one extra sapling and keep it in a large pot in the corner. If a gap opens, you fill it with a plant of the same age.
How fast does it grow, and how tall?
Slow in the first year or two while roots settle, then steady. In good conditions a young tree can add well under a metre to around a metre a year. Mature trees in old avenues become tall columns, often taller than a three storey house, while staying narrow. You can top them to hold a height, though the shape looks best left natural.
Do ashoka tree roots damage houses?
It is not known as a root-heavy tree, which is why it is planted so close to houses and walls in South Asia. Still, any root follows leaking water. Keep 2 to 3 m from house walls and 1.5 m from boundary walls, drains and underground water tanks. The real risk of planting too close is the crown rubbing the wall and staining it, and a lopsided tree.
Ashoka tree care for the first two years
Watering
- May and June, 45°C: deep water twice a week in Lahore and Multan, more often in sandy soil.
- Monsoon: only in dry spells.
- Winter: every 10 to 14 days; cover young plants on frost nights in Punjab and Islamabad.
Our guide to watering plants by season covers pot stage watering.
Feeding
Compost in February and September. Pale new leaves on alkaline soil often point to iron shortage; a layer of leaf mould and compost usually helps more than chemicals. Small amounts of mustard cake are fine.
Pests
Leaf-eating caterpillars sometimes strip patches in summer. Hand pick on small trees; big trees regrow. Mealybugs on young shoots wash off with a strong water spray and a little soap water.
Do not use Polyalthia leaves or bark as a home remedy in place of real ashoka; they are different plants, and any medicine decision belongs with a qualified practitioner. Tall columns near electric lines must be trimmed only by the electricity company. Some people react to tree pollen; the pollen calendar helps. If you spray anything beyond soap water, read the label, wear gloves and a mask, and keep children and pets away until it dries.
Grow it or skip it?
Plant it for privacy, a formal driveway or a narrow lawn in Karachi, Lahore, Delhi and most of the plains. Skip it if you want shade, flowers or fruit. More trees and flowering plants for homes are in Phool aur Paudhe.
Ashoka tree growing questions
How fast does the ashoka tree grow?
Slowly for the first year or two, then steadily, often up to around a metre a year with summer water and sun.
How far apart should ashoka trees be planted for privacy?
About 1.5 to 2 m apart in a row. Closer planting fills faster but the trees compete and lower branches thin out.
Can ashoka tree be grown in a pot?
Yes, for several years in a 40 litre or larger container, but it stays smaller and needs daily water in summer. For a long-term screen, plant in the ground.
Is Polyalthia the real ashoka tree?
No. Polyalthia longifolia is the false ashoka. The ashoka of traditional medicine is Saraca asoca, a different tree.
When should I plant an ashoka tree?
February to March or July to September. Avoid the heat of May and June and frost months.
Why are my ashoka tree leaves turning yellow?
Usually waterlogging, alkaline soil or old leaves dropping in spring. Check drainage first, then add compost.
Can I cut the top of an ashoka tree?
Yes, topping holds it at a set height, though it may branch at the cut. Do it in late winter.
Does the ashoka tree flower?
Yes, in spring, with small pale green star-shaped flowers that most people never notice, followed by dark berries that birds eat.