Most herbs require little attention once established. The maintenance will consist of cutting back plants in spring and summer to encourage healthy growth and a bit of tidying up while the plants are dormant over the winter period. If grown in containers, herbs will require regular watering and fertilization during growing period and some repotting or topdressing when necessary.
Most herbs are grown for their fresh young foliage. This may be cut back to produce a regular supply of leaves. For keeping a good leaf production some herbs will require some extra attention: remove the flowering stems of sorrel as they appear; keep the flowers of chives and marjoram until after flowering as they may be use as flavoring; variegated marjoram, mint and lemon balm will produce bright new foliage if the plants are cut back shortly before flowering as their color fade. Invasive plants should be checked regularly even if they are planted in sunken containers because they produce runners which must be removed before the plants will spread too far. Remove any reverted or plain shoots from variegated herbs as soon as they appear.
Dead-heading and pruning
If you do not want to save seeds from your herbs then you must remove the dead flowerheads from your plants so that the energy is channeled into new growth. Dead-heading annuals like borage, lengthens the flowering season. Some herbs like angelica self-sow prolifically so you might want to keep it under control by removing the dead flowerheads. Dead-head and prune shrubby herbs like lavender and thyme by trimming lightly after flowering. Hard pruning in spring encourage sideshoots and new growth from the base. Thyme is best pruned little and often during the growing season.
Herbs Routine Care
Mulch only established herbs that thrive in moist soil, such as mint and bergamot. In summer mulch after rain to retain moisture in the soil and improve the soil as it breaks down. Use an inorganic mulch such as grit around Mediterranean or grey-leaved plants in heavy soil to reduce the risk of rotting.
Most herbs are cut back in autumn but in cold areas leaving the dead foliage of herbaceous perennials until next spring will protect them from frost and wind. Remove any dead leaves that have fallen on thyme and other low-growing, evergreen herbs as they may encourage a fungal attack.
In cold regions tender herbs should be brought under cover or protected in some way. In spring cut them back and plant them outside again or propagate new plants from cuttings. Hardiness of some herbs like sage or lavender depends on the variety, as some may be fully hardy while others may be frost tender.
Herbs in containers
In hot weather check soil moisture daily and water them thoroughly when dry. Feed hers every two weeks with a weak liquid fertilizer during growing season. Over the cold periods bring herbs in containers under cover and put them in a place with good light. Frost-proof pots may be left outdoors as long as they are insulated with sacking to protect the herbs roots.
Check herbs regularly to see that they are not becoming pot-bound. Look for signs like rapid drying out, pale foliage or weak new growth. All those signs indicate that the herbs need to be repotted. Repot during growing season to encourage new root growth. If repotting is impractical then renew the top 2.5-5 cm of compost incorporating well-rotted organic matter or a slow-release fertilizer. After this it will be unnecessary to feed the herbs for about a month.
An edible garden should be also nice, so we use flowers for that. But we …