Rosemary Growing Calendar: What to Do in Each Season

The year at a glance

Unlike an annual herb, rosemary is a long-lived evergreen shrub, so no season starts from scratch. The work concentrates in spring, when you prune, feed a container plant and plant out; the rest of the year is picking, occasional watering and getting the plant safely through the cold.

Spring is the busy end of the year

Almost every job that involves cutting or moving the plant belongs here. Wait until the danger of hard frost has passed and you can see new growth starting, then prune, plant, repot and feed within the same few weeks. The plant then has the whole season ahead of it to recover.

Spring is also when winter damage becomes visible. Branches that were killed by cold turn dull gray-brown and shed their needles, and they will not recover, so cut them out at the base as soon as you can tell them apart from live wood.

1. Assess the winter damage first Scratch a doubtful stem lightly with a thumbnail. Green underneath means it is alive; brown and dry means it is dead. Remove the dead wood before you do anything else.
2. Prune to shape Take up to a third of the growth, always cutting back to a point where green needles remain below the cut. This is the year's main prune.
3. Top-dress or repot containers Scrape off the top couple of inches of old compost and replace it with fresh gritty mix, or move the plant into a pot two inches wider if roots are circling the base.
4. Feed pots once One light, low-nitrogen feed as growth starts is the entire year's feeding for a container plant. Plants in open ground need nothing.
5. Plant new plants Once the soil has warmed, plant out with the rootball proud of the surface. This gives the longest possible run of root growth before winter.

Do not be alarmed if a plant looks poor in early spring after a wet winter. Rosemary often sits dull and gray for weeks before it moves, and it is worth waiting until late spring before deciding a plant is dead.

Summer is harvest and cuttings

Aromatic oil concentration peaks in warm, dry weather just before and during flowering, so summer sprigs are the best of the year. Cut in the morning after the dew has dried, take a little from all round the bush rather than repeatedly from one side, and never remove more than a fifth of the plant in a single session.

This is also the window for propagation. Semi-ripe cuttings taken from late spring through late summer root fastest, and a batch stuck in early summer will be potted up individually by autumn.

Note the date of your heaviest cuts and how fast the bush refilled. Regrowth rates vary with season and plant age, and that record stops you over-cutting the same bush twice.

Autumn is about winding down, not tidying up

The instinct to cut everything back for winter is wrong for rosemary. Pruning now leaves open wounds and provokes soft growth just as the cold arrives, and both routes lead to dieback. Leave the plant alone and let its growth harden.

What you should change is water. Reduce watering steadily through autumn so the plant goes into winter on the dry side. Wet roots plus freezing temperatures is the combination that kills rosemary; either alone is survivable.

1. Stop feeding entirely Any feed from late summer onward pushes soft growth that will be killed by the first hard frost. A container plant needs nothing more until spring.
2. Reduce watering week by week Move a container plant from weekly watering to fortnightly, then to monthly. Judge by the weight of the pot rather than by a fixed schedule.
3. Move pots under shelter Shift containers against a wall, under an overhang or into a cold greenhouse, where they stay out of prolonged winter rain. Keep them in full light.
4. Clear debris from the base Rake fallen leaves and soft mulch away from the stem. Anything that holds moisture against the crown through winter invites rot.

In a mild garden with free-draining soil, an established plant in the ground needs nothing at all in autumn. Most of these jobs are for containers and for young plants in their first winter.

Winter: keep it dry, keep it bright, leave it alone

Rosemary is evergreen and does not go fully dormant, so it needs light all winter, but it grows so little that it needs almost no water. A plant brought indoors and treated like a houseplant, watered weekly in a dim corner, will be dead by spring: that combination of low light and wet compost is fatal.

Hardiness varies between forms, so the winter plan depends on which kind you have and how cold your garden gets. As a rule, upright kinds tolerate more cold than low spreading ones, and any plant in a pot is effectively less hardy than the same plant in the ground because its roots freeze through.

Cold drying wind does more visible damage than low temperature alone, browning the needles on the exposed side of a bush. A simple windbreak on the prevailing side is worth more than wrapping the whole plant, which traps damp air.

Catching up if you miss something

Because rosemary lives for years, most missed jobs can be picked up in the following season without lasting harm. The exceptions are the ones that involve cutting: a prune made at the wrong time, or one that went too far into old wood, cannot be undone at all.

Noting prune dates, the winter each plant came through and where each bush stands turns this table into something specific to your garden.