As soon as grafts begin to grow (usually around 15 days) the pots are gradually removed from sawdust, and when plants have made 15-20 cm. of growth (after 30-40 days) they are slowly hardened to air and sun, replanted in well-shaded beds, properly watered and cared for until they are set in nursery row.
3. Planting in nursery. The following spring they are set 60 cm. apart in nursery rows 1 m. apart in well-manured and well-prepared plots. Usual care during growth. With the 2nd year plants attain 1-1/4-1-1/2 m. and it is not uncommon to discover a nut. The 3rd year they make 2-1/2 m. at least with 8-12 cm. of girth and are ready for transplanting to permanent site.
4. Soils and situations. Mr. Treyves tells us that the walnut plantings in "lower Grésivuaudan" are on old alluvium of the Isère Valley and in limy marl soils of the upper slopes. A little farther away in Savoy, the walnut is vigorous in Jurassic or clay limestone soils. The same is true in Dordogne, in Corrèze, and in the Lot, where soils are of similar origin.
Walnuts are found at an average altitude of 600 m. but grow up to 1200 m. in Savoy, and particularly in Switzerland.
The best exposures are SW, W, and SE, sunny slopes, well protected from the north wind and late frosts.
Mr. Treyves has personally some plantings of walnut in Sologne, (where calcareous soils are lacking) and in Champagne, where the soils lack lime. He has noted that these trees grow and fruit normally.
Cultivation. It is important to keep soil around isolated trees well stirred and to increase the area of cultivation as the rootspread increases.
5. Rootstocks. For the present the plants chosen for stocks have come from nigra, the only one that has proved itself in the matter of "take". It does well in moist soils.
Mr. Treyves has personally tried to graft Mayette and Franquette on Torreyi. He has found the "take" and the union perfect. But even though vegetation is promising we must wait 22 years for a full test.
He proposes to lest all the "rootstocks placed at his disposal in order to acclimatize the good French varieties to all the soils which suit these stocks. Grafting on J. Torreyi will be useful to a [sera utile a un] stock that grows in dry soil, like nigra.