Mistake 1: Pruning spring-flowering shrubs in winter
Many spring-flowering shrubs, such as rosemary, broom or Cytisus, form their flower buds during the previous autumn. If they are pruned hard in winter, most of the flowering is removed. On the Cádiz coast, the mild winter invites garden work, but it is better to wait until after flowering for more severe pruning.
The alternative is light cleaning pruning, removing dry or badly oriented branches without touching the branches that bear buds. For example, a flowering rosemary can be lightly trimmed after the peak of flowering, but not before.
- If you are unsure of the timing, prune only what is essential and observe the plant for a year.
- Mark the flowering time of each shrub on the calendar to avoid repeating the mistake.
Mistake 2: Ignoring whether flowering is on last year's wood or current year's wood
The key is to know whether the plant flowers on branches that grew last year or on new shoots. Shrubs such as forsythia or winter jasmine flower on old wood: if pruned in winter, the flowers are lost. In contrast, Buddleja or hibiscus flower on current year's shoots and tolerate winter pruning.
A common mistake is to apply the same pruning to all shrubs in the garden. For example, in Sotogrande, lantana should be pruned in late winter, as it flowers on new shoots; while Coronilla valentina should be postponed until after spring flowering.
- Consult species-specific information or ask at the local nursery before pruning.
- When in doubt, carry out light thinning rather than severe cutting back.
Mistake 3: Trimming flowering hedges as often as green hedges
Hedges of flowering shrubs, such as rosemary, lavender or Pittosporum, should not be trimmed several times a year with the same intensity as a box hedge. If trimmed during full flowering, flowers are removed and the plant is stressed. On the Costa del Sol, lavender can be trimmed after the main flowering in late spring, and then given a light tip prune in autumn.
In contrast, a Pittosporum hedge tolerates more frequent trimming better, but it is best to avoid doing so just before flowering if you want to enjoy its scent.
- For flowering hedges, prioritise annual pruning after flowering and, if anything, a light tip prune.
- Never trim during peak flowering: besides losing flowers, you encourage disease entry through open wounds.
Mistake 4: Pruning during extreme heat or when there is risk of frost
In the Mediterranean climate, summer pruning with high temperatures can cause sunburn on exposed bark and water stress. Inland, where frosts are more frequent, pruning in late autumn can stimulate tender shoots that will die in the cold. For example, in inland areas of Cádiz province, it is better to wait until the risk of frost has passed to prune sensitive shrubs such as hibiscus.
On the coast, the heat is not so extreme, but pruning in mid-August can coincide with the peak flowering of some species, such as oleander, and remove it. Better to postpone until September.
- Carry out formative pruning in late winter or early spring, depending on the species.
- Avoid pruning on days of strong wind or stifling heat to avoid damaging tissues.
Mistake 5: Not differentiating between coast and inland
The mildness of the coastal climate allows pruning later in autumn and earlier in spring, but inland frosts set the calendar. A shrub such as rosemary, which on the coast can be pruned after winter flowering, inland is better pruned in early spring, when the risk of frost has decreased.
Furthermore, environmental humidity on the coast can favour fungi in pruning wounds; make clean cuts and, if necessary, protect them with wound sealant (without overdoing it).
- Adjust the pruning calendar to the local conditions of your garden, not to those of a generic region.
- In inland areas, delay pruning of sensitive shrubs until minimum temperatures stabilise above 5 °C.
Mistake 6: Pruning with unclean tools or making incorrect cuts
A common mistake is to use hedge shears for flowering shrubs, leaving torn cuts that do not heal well. For branches thicker than one centimetre, use one-handed or two-handed pruning shears, depending on the thickness. Disinfect the blades between plants, especially if you suspect disease.
The cut should be clean, at a slant and just above a bud facing outwards from the plant, to encourage open growth. In shrubs such as wild olive pruned as ornamentals, a badly oriented cut can cause crossing branches and future problems.
- Sharpen and clean tools before and after each pruning session.
- Make slanting cuts and never leave long stubs that could rot.