Sage is a popular cottage garden herb and one with a long culinary and herbal healing history in the UK. One sage plant is usually enough for home growers and this can be a great addition to a herb garden in a polytunnel, or simply planted as a companion plant between other food crops under cover. Sage can be grown direct in the soil or polytunnel beds or can be grown as a container plant and moved as required. Imagine being able to make your own sage and onion stuffing whenever you want.
Sage loves a warm, sunny and sheltered spot so a polytunnel should be ideal. In order to provide the best possible growing conditions, it is best to add plenty of compost or well-rotted manure to the tops of your polytunnel beds. (In a 'no dig' system, this should be left on top rather than dug in, so as to preserve and protect the soil ecosystem.)
Sow or plant sage between March and May and water your sage plants regularly, especially during dry spells. Avoid overwatering however, as sage cannot tolerate having wet or waterlogged roots. In the winter, raise container grown sage up off the ground to allow for good drainage and be careful not to overwater in your polytunnel during colder weather.
Pruning your sage plants after they flower will help to maintain an attractive shape and will encourage lots of new foliage growth. To make sure that the leaves remain in good condition over the winter months, you may wish to give the tops a little more protection with a layer of horticultural fleece, though this extra protection may not be required in a polytunnel in more southerly portions of the UK.
Sage is said to be a good companion plant for a wide range of crops, including brassicas (as a trap crop that attracts cabbage butterflies), beans, carrots, strawberries and tomatoes. In general, sage can benefit all crops that require pollinators by attracting honey bees and other beneficial insects to your polytunnel.
Sage is an evergreen and so its leaves can be picked at any time for use in the kitchen. Sage can be used fresh or dried or frozen. Sage takes a while to dry but when it is dry it can keep for a year or so in an air-tight container.