It sure doesn’t look very appetizing. The name won’t arouse your palate either, but sow thistle (Sonchus oleraceus) makes a tasty salad or cooked green. Sonchus is Greek for hollow (referring to the stems) and oleracea means vegetable or herb-like. This species is an annual, but perennial sow thistle (Sonchus arvensis) can also be found here.
This lettuce relative thrives in cool weather. Like its composite cousin its stems produce a milky substance that can be a little bitter, but the leaves are mild. Young foliage is great for salads, while older specimens are better stir-fried, boiled or steamed. They taste similar to Swiss chard or spinach. At any growth stage they are milder than dandelion greens. Sow thistles are also one of the more plentiful weeds in our area.
Elongated silvery tinged leaves with reddish edges and midribs vary in shape. Leaves are roughly oval-shaped on young plants but become what botanists call ‘pinnatifid’ (lobed on opposite sides of the midribs) when they are older. Leaf edges look prickly but are only slightly so. When the plant matures, yellow dandelion-like flowers generally bloom in the morning and close in the afternoon. As they further mature flowers ripen to a white down like dandelions do, and seeds blow everywhere. For this reason we need not encourage them. Leaves also become bitter when plants flower.
Sow thistle was originally brought here from England as a livestock feed. It was originally fed to lactating sows. Those who have rabbits can supplement their rations with this herb also known as hare’s thistle.
It has also been called milk thistle because of the milky juice in the leaves and stems. True milk thistles are one of the most widely used medicinal herbs, but they’re an entirely different plant with spiny leaves and purple flowers.
Sow thistles begin to grow in numbers in early fall, but you must be careful harvesting then. Aphids love them and finding hundreds of tiny crawling insects in your stash can put you off feed. When the weather warms up in late spring aphids again are prevalent. Otherwise, sow thistles are fine table fare. Leaves are high in Calcium, Phosphorus and iron as well as vitamins A and C.
As mentioned earlier sow thistle is invasive. You might not want it in your lawn or flowerbeds. Annual sow thistle can be controlled quite easily without chemicals. Keep your flowers weeded initially and don’t let plants go to seed. They are easy to pull as they have a single taproot that generally stays in one piece. In lawns, sow thistle is often a problem in the establishment phase, but after that a healthy thick turf usually chokes out emerging seedlings.
Cultivation is of little help with the perennial type. Roots can spread to five feet deep and are more branching. Even the tiniest root sections left in the ground can produce new plants. Eliminating it until your lawn gets established is a challenge. This perennial type is a double threat as it also is a prolific seed producer.
Ted Manzer teaches agriculture at Northeastern High School.