Expert advice: Can I grow herbs all-year-round?
PUBLISHED: 11:34 20 March 2019 | UPDATED: 11:34 20 March 2019
Garden expert Martyn Davey answers a reader’s question about how to grow herbs on a windowsill.
I would like to grow herbs all year round to supply my kitchen with at least a few herbs in the gloom of winter as well as bright sunny days. Can you suggest how to do this without a heated greenhouse? I have a large north facing windowsill in the kitchen can I use this or is it too dark?
S. Butler, via email
Herbs are great to grow in summer outside but do struggle in the cooler, shorter days of autumn and winter. If you have a sunny area in the garden, that you can use possibly for herbs and vegetables, this will give much better results than trying to grow on a cold and dark north facing windowsill. Extend the season with the use of a cloche to protect the herbs from the worst of the winter cold and encourage early growth in spring.
The use of a cloche is suitable for growing parsley, both the moss curled (Petroselinum crispum ‘Moss Curled’) and the French and Italian parsley (Petroselinum crispum ‘Italicum’), and coriander (Coriander sativum ‘Cilantro’) which is better for leaf production and less likely to bolt than the plain sativum. Also, if you like chives (Allium schoenoprasum), salad rocket (Eruca sativa) and lovage (Levisticum officinale), all these are well worth growing although with the possible exception of chives they all need to have regular replacements as they tend to grow fast and then run to seed.
Other herbs such as basil, will perform best on a bright and sunny windowsill and really can only go outside if we have another really hot summer. Although basil likes warm conditions it also needs to be kept well-watered and feed every two week with a high nitrogen feed not a tomato fertiliser as this encourages flowering.
With other perennial herbs like mint, sage, thyme and rosemary, I like to grow these in large pots outside but with the flexibility to move them around either for outdoor cooking or to promote better growth from the plants. Rosemary and sage need to be in sunny positions to do well and need a free draining soil as they will not do well if left to soak. Mint on the other hand likes sun but also needs lots of moisture and will do well planted in a bucket with only a few drainage holes this also helps to keep it under control. These herbs unlike to seed raised annuals will need to be cut back in spring to encourage new growth and definitely by grown plants from the supermarket or garden centre.
There is no shame in buying your herbs from the supermarket as ready-grown plants, particularly basil as it will normally have at least 20 plants in the pot that can be split out and potted individually in 9cm pots and grown on. The price for these herb pots is usually between £1 and £1.50 and you will find you get what you pay for. I have found an extra 50p can make a huge difference in quality.
Many of these plants will have been forced on and had a rough journey to the supermarket so it is best to water them well when you get them home and cut them hard back to encourage new growth, which will need to be harvested regularly to keep the plants productive and don’t let them flower.