Tarragon is a perennial herb that has many applications in cooking. There are two varieties, French tarragon and Russian tarragon and French tarragon is said to be far superior in terms of the flavour. Tarragon is a good addition to a polytunnel herb garden and, if well situated and cared for, will remain productive for a few years before there is a need to replace it. Since tarragon is not frost hardy, it may need a little more winter protection in some areas in an unheated polytunnel.
Tarragon is usually grown from small plants. These should be purchased in around March or April and planted in a container or in a polytunnel bed between April and August. French tarragon, as mentioned above, is the best one to go for. You can buy these plants at many garden centres and plant nurseries, either in person or online. It is not possible to grow French tarragon from seed.
It is important to keep the plants well watered to avoid any check to their growth. However, in the winter, container plants should be placed onto pot legs or raised up to prevent waterlogging and allow the water to drain freely.
It is best to harvest regularly to keep your tarragon plants at a height of no more than around two feet, as this will help to ensure that the plant remains healthy and does not become unstable. When it becomes taller than this, the plant is at risk of toppling over.
The scent of tarragon is unpleasant to many pests and will be a good addition to your polytunnel, helping to repel a range of these pests and therefore may be a good companion crop for a wide range of different fruit and vegetable crops. Tarragon is said to be especially beneficial as a companion plant for aubergines. Tarragon is believed to be a 'nurse plant' in that when grown near a range of crops, it can help them to grow well and strong.
The slender leaves of tarragon are to be picked as and when they are required any time between May and September. Remove the growing tips with a pair of secateurs and then strip the leaves from each sprig for use in the kitchen. Tarragon can be used fresh, frozen into cubes for later use, or dried and stored in an airtight container. It is best used fresh but will also work when dried in a range of different recipes.