106 ASPARAGUS 
must be removed when the asparagus begins to shoot. 
When the shoots are about three inches out of the 
ground they may be cut. The mats must be taken off 
in the daytime, but the heat must be well kept up, else 
the roots and buds will fail to push. The beds are 
forced every second year only. The gathering of the 
asparagus may continue for about two months but no 
longer, or the plantation would be injured. When the 
gathering is over the frames are taken away, and the 
soil which was dug up from the alleys is put back 
again. 
An ingenious method of forcing asparagus in the 
field by means of shallow tunnels was devised and suc- 
cessfully carried out by Prof. J. C. Whitten, at the 
Missouri Experiment Station, who gives the following 
account in Bulletin No. 43: 
‘«’The field selected for the experiment was planted 
to asparagus about ten years ago. The plants were 
in fair vigor, though of a small variety. ‘The first 
section forced embraced six rows, four feet apart, and 
fifty feet long. Fig. 35 shows this section with one 
tunnel uncovered. ‘Trenches were first made between 
the rows. ‘This was done by plowing between them, 
twice in a place, throwing the furrows on the plants 
so as to cover each row with two furrows of loose 
earth. ‘These trenches between the rows were then 
made uniform by means of the spade. When finished 
they were three or four inches lower than the crowns 
of asparagus in the adjacent rows. These trenches 
were then covered with twelve-inch boards, which 
rested on four-inch blocks, placed at frequent intervals 
along either side of the trenches. This formed tun- 
