Upright vs Trailing Rosemary: Which Type to Grow and How Hardy They Are

Two habits, one plant

All rosemary belongs to the same species, but growers group it into two broad habits. Upright forms send stiff stems more or less vertically and build into a shrub three to five feet (90 to 150 cm) tall over several years. Prostrate or trailing forms grow outwards and downwards, rarely exceeding a foot to eighteen inches (30 to 45 cm) high but spreading two or three feet or more across.

There are also plenty of plants that sit between the two, growing as a low mound that arches at the edges. Habit is also influenced by conditions: a plant in poor light stretches and flops whatever its natural form, and a trailing plant given a wall to hang over will run much further than one on flat ground.

Upright forms are the workhorses

If you want a lot of rosemary to cook with, or a low informal hedge, choose an upright form. The stems are long, straight and easy to cut in useful lengths, the plant carries a large volume of foliage once mature, and the open structure lets air through, which reduces mildew in a damp garden.

They are also the more cold tolerant group as a rule, and they hold their shape without support. The trade-off is size. An upright rosemary needs real space, and because it will not reshoot from bare wood, you cannot keep one small indefinitely by cutting it back hard.

1. Give it three feet of space Plant well away from paths and neighboring shrubs. A plant that has to be cut back every year to keep a path clear will go bare at the base and fail early.
2. Shape it early Pinch the tips through the first two seasons to build branches low down. An upright form left unpinched becomes a few tall stems with foliage only at the top.
3. Use it for a low hedge Spaced eighteen inches to two feet (45 to 60 cm) apart, upright plants knit into an informal aromatic hedge. Trim lightly and often rather than cutting hard once a year.

An upright plant is also the easier one to harvest heavily, because you can take long sprigs from the top and sides without spoiling the shape. On a trailing plant the same amount of cutting leaves obvious gaps.

Trailing forms are for edges, walls and pots

Prostrate rosemary earns its place where an upright shrub cannot go. Planted at the top of a wall, at the edge of a raised bed or on a bank, it cascades down and covers ground that is difficult to plant, and it does it in the sharply drained, sunny conditions rosemary most enjoys.

In a container it is the more manageable choice, staying naturally low and spilling over the rim rather than growing top-heavy and blowing over. The flavor is the same as an upright plant, though the shoots are shorter and thinner, so harvesting takes more cutting to gather the same amount.

1. Plant it where it can fall The habit only shows properly with something to spill over. On flat ground a trailing plant sprawls, roots where the stems touch and can become a tangled mat.
2. Keep the crown clear Because the growth sits close to the soil, fallen leaves and damp mulch collect around the base. Rake them away and use grit mulch beneath the plant.
3. Layer it almost effortlessly Trailing stems in contact with soil often root by themselves. Pin one down in spring, and by the following season you can sever a fully rooted new plant.
4. Watch for a bare middle The center of a spreading plant thins as the edges extend. Light tip pruning across the whole plant in spring keeps growth coming from the middle too.

Hardiness differs, and the pot matters more than the type

As a group, upright rosemary tolerates more cold than prostrate rosemary, and within each group there is a wide range, so the safest approach is to buy plants raised locally and ask how they perform in your area. Cold damage typically shows first as browning on the windward side and dieback of the youngest shoots.

Whatever the type, growing conditions shift hardiness more than habit does. A plant in well-drained soil, kept dry and unfed from late summer, survives temperatures that would kill the same plant in wet, rich soil that was still being watered in autumn. And any plant in a container is effectively less hardy than one in the ground, because its roots freeze all the way through instead of being insulated by soil.

Record which plants came through each winter and where they were standing. Two plants of the same type in different corners of one garden often behave completely differently, and after a couple of winters your own notes beat any general hardiness rating.

Choosing between them

Work backwards from the site rather than from the plant. If you have open ground in full sun, free drainage and space for a shrub, an upright form will give you far more to pick and last longer. If you are working with a wall, a raised bed, a bank or a pot on a terrace, a trailing form will suit the position and need less correction.

In a cold or wet garden, growing an upright form in the ground for cropping and a trailing form in a pot you can move gives you both habits and a spare plant if one winter goes badly. Since both root easily from cuttings, it costs little to try both and see which does better for you.

Whichever you choose, look at the plant rather than the label when you buy. Short internodes, dense needles and firm growth right down to the base indicate a plant that was grown hard in good light, and that is a better predictor of how it will perform than its habit.