Planting a Mango Tree: Grafted Trees, Seedlings, Drainage and Pot Culture

Grafted wood flowers young, seedling wood does not

The single decision that governs how long you wait for fruit is whether the tree carries grafted wood. A graft is a piece of a tree that has already flowered, so it arrives sexually mature and starts producing panicles two to four years after planting regardless of how young the roots underneath it are. That is the normal route to fruit in a garden, and it is why nurseries sell grafted trees at a premium.

A tree raised from a stone has to grow through a juvenile phase before it can flower at all, and in mango that phase commonly runs six to ten years and sometimes longer. During that time the tree does exactly what a forest tree does: it puts everything into height. Plenty of people have a fifteen-foot seedling in the garden that has never once flowered, and it is not sick, it is simply still a child.

There is a second complication that surprises people. Many mangos produce polyembryonic seed, meaning a single stone contains several embryos and most of them are clones of the mother tree rather than the product of a cross. Where that is the case, a seedling can be genuinely true to the fruit you ate. Where the seed is monoembryonic, one seedling comes out of the stone and it is a genetic lottery. You cannot tell which you have until several shoots do or do not appear from one stone, so treat a seedling as an experiment and plant a grafted tree if you want a crop on a schedule.

If you already have a well-grown seedling, do not pull it out. Once the trunk is about half an inch (1.2 cm) thick, you can graft mature wood onto it and convert the years you have already invested into a tree that will flower on time. Graft in warm weather while the wood is not in active flush.

Drainage first, then everything else

Mango tolerates a long dry season without complaint and drowns in a wet week. The roots want air, and on heavy ground the tree will look fine for a season or two and then decline for no obvious reason as the root system rots away beneath it. Before you pick the spot on aesthetics, test it: dig a hole a foot (30 cm) deep, fill it with water, let it drain, and fill it again. If the second fill has not disappeared within about eight hours, do not plant at grade there.

The answer on slow ground is a mound. Heap native soil into a mound twelve to eighteen inches (30-45 cm) high and three or four feet (90-120 cm) across, and plant into the top of it so the root zone sits above the wet layer through the rainy months. This is not a refinement for perfectionists; on clay it is the difference between a tree and a stump.

Mango also has a deep taproot when it is allowed one, and a site with a hardpan or a high water table cuts that short. It will still grow, but it will need irrigation forever and it will blow over more readily in a storm. Pick the highest, best-drained corner you have, in full sun, away from the drip line of larger trees.

1. Dig no deeper than the rootball Make the hole exactly as deep as the rootball and about twice as wide. A deeper hole backfilled loose lets the tree settle, and a sunken trunk base invites collar rot in the first wet season.
2. Backfill with what you dug out Do not fill the hole with compost or bagged potting mix. That creates a sump that holds water against the roots and discourages them from ever leaving the hole. Put organic matter on the surface as mulch instead.
3. Keep the graft union clear Set the top of the rootball an inch (2-3 cm) proud of the surrounding soil and taper soil up to it. The swollen union a few inches up the trunk must stay above soil and above any mulch you add later, or the scion will root and you lose the rootstock's benefit.
4. Handle roots gently and stake low Slide the rootball out intact and cut only roots that circle the pot. Stake only if the site is windy, use a low stake that lets the trunk flex, and remove it after a year so the trunk builds its own strength.
5. Water in and then back off Give five to ten gallons (20-40 liters) slowly at planting to knit the rootball to the native soil, then water deeply every four or five days for the first two months. Once established, deep and infrequent beats little and often.
6. Shade the trunk for the first two summers Young mango bark is thin and burns on the sunny side. Paint the trunk and lower limbs with white water-based paint thinned by half, or wrap loosely with light cloth, until the canopy shades itself.

Spacing, and the sun a mango actually needs

Full, unbroken sun is not negotiable. A mango in half shade grows perfectly good leaves and sets very little fruit, because flowering depends on wood that has ripened in strong light. Give a grafted tree at least twenty to twenty-five feet (6-7.5 m) from buildings, boundaries and other trees, and if you plan to hold it at ten or twelve feet (3-3.5 m) by annual pruning, you can bring that in to about fifteen feet (4.5 m).

Shelter matters more than most people expect. The flower panicles are brittle and the developing fruit hangs on a long thin stalk, so a windy site strips flowers and scars fruit against the leaves. A hedge or fence on the prevailing side, set far enough back not to shade the tree, saves a proportion of the crop every year.

Avoid planting where irrigation sprays the canopy. Wet foliage during flowering is the trigger for the disease that ruins mango flowers, and a lawn sprinkler that soaks the tree every evening does more damage than a fortnight of rain.

A mango in a large pot under cover

In a climate that drops below about 40F (4C) in winter, a container under cover is the only honest way to grow mango, and it works better than its reputation suggests. The tree must be grafted, because you cannot house a seedling for the decade it needs, and it must be one that will accept being held at six or seven feet (2 m) tall. Expect a handful of fruit rather than a crop, and treat every one as a small triumph.

Pot up in stages. A young grafted tree moved straight into a half-barrel sits in a wet mass of mix it cannot dry out, and mango is unforgiving about that. Step up one size at a time in spring, use a coarse free-draining mix built on bark and pumice or perlite rather than a peat-heavy compost, and never let the pot stand in a saucer of water.

The overwintering routine is simple and it must be followed exactly. Bring the pot in before nights fall below 50F (10C), put it in the brightest position you have, and cut water sharply. A tree indoors in dim winter light is barely transpiring, and watering it on a summer schedule kills it through the roots. Once nights are reliably above 55F (13C) again, harden it back to full sun over ten days or the first flush will scorch.

Under cover has one large advantage worth naming: you control whether the flowers get wet. A tree flowering in a bright porch or a greenhouse escapes the rain that ruins outdoor panicles, which is why potted mangos in cool climates sometimes set fruit more reliably than garden trees in the wet tropics.

Write down the planting date, whether the tree is grafted or a seedling, and where the graft union sits. In four years, when you are trying to work out whether a tree that has not flowered is late or simply juvenile, that one line of record answers the question immediately.