Evergreen Magnolia Magnolia grandiflora Alta

Alta carries the same heavy dark glossy leaf as any evergreen magnolia, and the same rusty brown felt on the reverse, but holds it on a tight upright column instead of a broad crown. That is the whole reason to buy it: height in a strip of ground where a spreading tree would push against the building. It does flower once it has age on it, cream white and lemon scented, a few at a time through the warmer months, but nobody chooses an Alta for the blooms.

Measure the narrowest point first

Buying decisions with Alta are made with a tape measure, not a plant list. Set columns 1.5 to 2 metres apart down a driveway or a side boundary and let them touch into a continuous face of leaf, or space them wider if each tree is meant to read separately. Keep the line far enough off a fence that the lower branches are not being cut flat every year, because once the skirt is gone the column reads as a bare trunk with a hedge on top and it will not come back.

The narrow bed is the problem

Alta ends up in exactly the positions with the worst ground: a strip beside a slab, a driveway edge backfilled with builders rubble, a planter one spade deep over compacted fill. In that soil it simply stops. Lower leaves yellow and drop, the column thins from the bottom, and at slow to moderate growth it will not trade its way out of the problem the way a fast tree would, so the damage is semi permanent. Break the ground up well below and well beyond the root ball, improve it with compost along the whole planting line rather than in individual holes, and mulch the length of the bed. If the soil cannot be fixed, shift the line rather than buying a larger pot size and hoping. Autumn or early spring planting lets the roots settle before heat or cold arrives, and full sun builds a denser column than part shade.

Pruning that keeps the shape

Almost nothing is needed. Take out a shoot that breaks the outline or crosses into the middle of the column, in late winter before the new growth pushes, and stop there. Never shorten the leader to hold height. Evergreen magnolias do not hide a cut like that, and a stubbed column stays lopsided for years at this rate of growth. Feed in early spring and again after flowering with a complete slow release fertiliser for acid loving plants, water deeply through the first two summers while the roots spread, and keep mulch off the trunk so the collar stays dry.

Alta against the wider selections

Coolwyn Gloss is the alternative anywhere there is room for it, with a broader glossier leaf and a heavier green wall, but it needs the width to do that. Exmouth is a different scale again, a full sized tree with a wide skirt that eventually owns the ground beneath it. Alta is what you buy when the available width is fixed at a metre or two and cannot be negotiated, and it is the one selection among the evergreen feature trees here chosen for what it does not do, which is spread.

Choosing a size

This plant is available in 10 sizes, from 250mm up to 400L, priced from $109.00 to $2199.00 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. Every size here is established stock rather than a starter plant, so this line is intended for immediate effect rather than for growing on. Not sure which to choose? Read our guide to choosing a magnolia.