How to grow the turnip in a biological way
The turnip (Brassica rapa subsp. rapa) is grown for its round root and, to understand how to grow the turnip in a biological way we must know the characteristics and physiology of this plant. Meanwhile it must be said that the turnips are distinguished by a notable chromium morphism: we can find white, yellow, purple or red turnips but they all have similar characteristics and necessities. Although it is a species that is not cultivated throughout Italy, it still has great food importance. The turnip seeding should normally be done at the beginning of summer; since the turnip cultivation cycle oscillates between 50 and 80 days (depending on the climatic area), they are harvested from late autumn until late winter.
Choose mostly soft, non-substantial and deep soils. The sowing can be anticipated in the most southern areas, being able to anticipate also at the end of February. The plant should be sown broadly, with very sparse seeding intensity. As for the depth of sowing, we recommend around half a centimeter in loose soils, decreasing depth in the hardest and most compact ones. After the germination, thin out, waiting for this operation that the turnips have reached a height around 5 – 10 cm and will have emitted at least 3 – 4 leaves. The thinning is done by eliminating the weaker turnips and leaving a plant every 15 – 20 cm along the row. Clearly with longer distances you will get turnips with larger roots but then you have to pay attention to the weeds and then possibly provide with a straw-based mulch. In case you buy the seedlings in the nursery (or prepare a seedbed) we recommend about 20 cm between one plant and another and 25 – 30 cm between the rows.
If you have done good mulching you will have avoided the need for continuous (through weeding) to eliminate the antagonistic herbs. In this case the irrigation (which should be done often and little) can be thinned out in time (remember that if we administer a little water, the turnip will acquire a more harsh and pungent flavor).
Important is the fertilization that must be done with mature manure or compost; some recommend nitrate fertilizers but it is a technique that I absolutely discourage because of the direct absorption of nitrates in the roots and the fact that the plant (although presenting larger and inviting roots) has lower organoleptic qualities and becomes more susceptible to parasitic attacks. The organic substance must be prepared and distributed before installation or sowing. The presence of a good organic fertilization will also allow not having to resort to fertilizations during cultivation and to a healthier product. To organic fertilization, during the vegetative phase must be added nettle macerates that allow a strengthening of the defenses of the plant and provide elements useful for its growth and maturation.
To understand the era of harvesting turnips is rather easy: when the root comes out from the ground means that the turnip is ready for harvesting. Attention, in the northern areas when there is a risk of frosts; in this case, advance the harvest to avoid damage to the plant.