Growing veg: Turnips
Before I go any further I should explain that in Ireland these are white turnips because turnips are what I grew up with as swedes. Swedes, or turnips in Ireland, are a different vegetable, sown in May and harvested in autumn for winter use and have yellow (or pale apricot) flesh. Here I am talking about the vegetable that Baldrick (in Blackadder series 2) loved so much. The fact that Baldrick’s enthusiasiasm for this vegetable is funny, is because turnips are one of the most despised of all vegetables. And if you buy them in shops it is not surprising because they don’t sell well and they are frequently of mixed sizes but always slightly wrinkled because they are such slow sellers. This is a shame because they are really quite delicious.
Turnips can be stored for autumn and winter use, especially those with yellow flesh, and the quick-growing white turnips which most frequently have purple or green shoulders.
Forget any association with filling ingredients for winter stews and think of these young turnips as a delicious summer and autumn vegetable. They grow quickly, the tops are edible too and, if picked young, they are crisp, tasty and tender.
Turnips grow best in fertile, well dug soil with plenty of organic matter. The soil should be kept moist and they will grow in part shade in the height of summer though full sun is best. They can also be grown in patio pots of multipurpose compost too if you don’t have a garden. Seeds can be sown from March (if it is mild) until late June. They need average treatment, sown thinly and about 1cm deep. As soon as they are up and large enough to handle, water the rows and thin out the seedlings to about 5cm apart so they can swell. The faster you grow them – meaning the more you water them – the better they will be. Young plants pulled when thinned can be used in stir fries or steamed. When the roots are 5cm across the roots can be harvested and if you pull every other root you can leave these to get larger. But Ideally they should be eaten smaller than a tennis ball.
Apart from slugs, flea beetle also love the leaves of turnips and can be destructive but if the plants are growing fast they often grow out of the problem. In theory club root can be a problem. The biggest issue is if the plants are not thinned when young and if the ground is dry the roots will not swell.
Pull the roots as you need them so you eat them fresh. They can then be eaten grated raw, steamed, stir-fried and, if you must, boiled and added to stews.
The Biking Gardener 
The first turnips I grew were just turnip greens, without distended rots. I no longer grow them because they grow wild, along with wild radish and wild mustard, on the edge of the forest. They are not as good as the garden varieties, but they are good enough for me. If I grow turnips in the garden, they will be for the distended roots, and the greens on top will be an added bonus. They may not be as good as varieties grown for greens, but they may be better than wild sorts.
I am sure that foraged greens are higher in nutrients than cultivated crops.
? I would think that those that were developed for culinary application would be more nutritious. I really do not know. Most of the mustard is likely what remains of old cover crops. Some of the others might be also. They were not developed to be eaten. Some are likely feral descendants of vegetables. Others have made the same observation that the wild sorts are more nutritious, but it seems to me that the domestic sorts would be better.
Because the bitterness in wild veg, which has been bred out of them, is supposed to be what is good for us, I assume that foraged veg would be more nutritious. They certainly have the advantage of being organic, is that matters to you – depending on where they are growing!
I did not put that much thought into it. I am not sure if they are unpleasantly bitter, since my sense of taste is somewhat limited. They taste fine to me. I only collect them because they happen to be so abundantly available, and some of them get in my way. At work, I must sometimes remove some of these vegetables. Furthermore, stinging nettle is quite abundant across the road, but not the sort of vegetable I would want to grow in the garden.
Never common here and not a vegetable I grew up with and only grew once. I don’t grow swedes either but do eat them.
I agree that swedes are something to buy rather than grow – more of that sometime soon!