Irrigation. — 107 



of the plants are kept well supplied with moisture all the time, 

 and the growth, therefore, is rapid and healthy. 



When watering beds by subirrigation, it will occasionally be 

 desirable for the gardener to examine the soil at the bottom of 

 bench, in order to be able, judging from its con- 

 dition, to properly gauge the quantity of water 

 to be turned on. A home-made soil-tester, like 

 the one here shown, will come quite handy in 

 such an emergency. It is simply a tin tube with 

 a wooden pestle, built something on the principle 

 of the boy's pop-gun. The tube is pressed down 

 into the bench, then withdrawn with the core of 

 soil remaining in it, and finally the core pushed 

 out by means of the wooden pestle, ready to be 

 examined. 



Another style of underground watering of 

 greenhouse lettuce — the simplest and cheapest of 

 all, and just as effective as any other — consists of 

 turning water into four-inch flower-pots sunk 

 into the bench in the centre between every four 

 plants. Cross-section of bench thus arranged is 

 here shown. A few dozen pots reach over quite 

 a bench and may be sunk in their proper places 

 at the time the plants are set. On account of its 

 great simplicity, I prefer this method to the other 

 for my uses. 



The principle of subirrigation is now also applied to water- 

 ing seed flats or pans. Overhead water applications to small 



^■1^ 





n. 



Subirrigation by Flower Pots. 



seeds or small plants in seed pans has always been objectionable 

 and risky. Every objection is met and every risk avoided, how- 

 ever, when we place the flat into the " water-bench," a shallow. 



