Cauliflower Root

Root Habits in Relation to Cultural Practice.--The root systems of cauliflower and cabbage have many similarities and the method of planting and growing cauliflower is very much the same as for cabbage. Climate is a more important factor than soil; the vigorous and extensive root system develops well in nearly all kinds of soil. Growth is promoted by thorough soil preparation and the liberal application of manure or other fertilizers. A constant supply of moisture for the roots should be maintained so that growth of the plants is never checked. This may be promoted by frequent tillage. Cultivation, as for cabbage, should be shallow. Because of the thorough occupancy of the surface-soil layers by the maturing root system, it would seem that, as in the case of cabbage, late cultivation might do more harm than good. All of the soil between rows spaced 2.5 to 3.5 feet apart is thoroughly occupied.  

From  the book:

ROOT DEVELOPMENT OF VEGETABLE CROPS   (1927)

by JOHN E. WEAVER Professor of Plant Ecology, University of Nebraska 
and WILLIAM E. BRUNER Instructor in Botany, University of Nebraska