It- 



Tune, 1922 



THE CANADIAN HORTICULTURIS' 



133 



Dividing Iris Clumps 



F. H. Byshe, Forestry Branch, Ottawa. 



THE best time for dividing tall- 

 bearded irises appears to be soon 

 after flowering. They then seem 

 ;o get squared away in preparation for 

 he next season's blooming, and you 

 jive them their best opportunity when 

 rou make any necessary re-arrangement 

 )efore this process is far advanced. 



"Why divide them?" you say. Well, 

 here may be several reasons. You may 

 vant to give a rhizome or two to a 

 ■riend, or you may want to move the 

 jJump or a portion or it to another part 

 jf the garden. Again, the clump may 

 lave been in place long enough to have 

 xhausted the food value of the soil, or 

 t may have grown so large that for the 

 ake of its own health and symmetry it 

 hould be lifted and reset. You will 

 ippreciate this the better if you recall 

 ^e fact that the iris, hke other plants, 

 Iraws upon the food elements of the 

 oil in which it grows and that in time 

 he soil becomes impoverished. When 

 his condition arises, the growth be- 

 omes less vigorous and the flowers less 

 lumerous and smaller in size. I do not 

 BOW to what extent irises "foul their 

 twn nest" or contaminate the soil in 

 Thich they grow, as other plants are 

 uiown to do, but it is a possibility to 

 )e considered. 



Rhizomes Lift Themselves 



in, you will have observed in an 



clump of iris that the rhizomes have 



pparently lifted themselves above the 



round level. To account for this we 



honld understand that the rhizome 



( rs only once. If you look at a 



: ip of iris in the spring you will 



ver the dried up stalks which bore 



vear's flowers. These stalks will be 



.1 growing out of the "neck" or 



nd of the rhizome, and if you break off 



tie stalk, you will find that the rhizome 



p.' 



Mclui 



has already begun to callous at the 

 point of breaking. That rhizome will 

 not usually flower again but will send 

 out "offsets" which will develop into 

 rhizomes that will flower in their turn. 

 In time the old rhizome will decay and 

 disappear. Incidentally, this decay is a 

 natural process and should not be con- 

 fused with the disease known as "Iris 

 rot" (Pseudomonas iridis). In a long 

 established clump these new rhizomes, 

 not having sufficient ground space, 

 often gr6w on top of each other, which 

 accounts for their appearing above 

 ground. This condition will be found in 

 clumps three to five years old, the time 

 varying according to the vigour of the 

 growth. 



Replanting 



Assuming then, that you are going to 

 lift and reset an old clump, with a shovel 

 or spading fork, remove it entire. 

 Continue shovelling until considerable 

 earth has been removed and refill with 

 fresh soil. Then take the clump and, 

 after shaking it free of earth, pull the 

 rhizomes apart. In replanting, whether 

 in the old or the new location, select 

 only those rhizomes which have not 

 flowered, and cut away the old rhizomes 

 that have fulfilled their purpose. These 

 may be discarded unless they give 

 promise of producing additional offsets, 

 in which case they may be planted in a 

 separate location. It is not advisable to 

 replant iris in large unbroken clumps. 

 It is, of course, unnecessary to lift a 

 clump solely for the purpose of removing 

 a rhizome or two. Take a spading fork 

 and loosen the roots at a point on the 

 edge of the clump. Then with the hand, 

 pull away what rhizomes you require. 

 A chisel is a good instrument with which 

 to sever a stubborn member from its 

 family group. 



B^^JSS^* 



Ti 



HOW BUSINESS FIRMS CAN IMPROVE THE COMMUNTTY 

 \ of several tulip beds in front of the ofiiccj of Joho Bertram & Sons, Ltd., Dundos, Out. 



There has been considerable discus- 

 sion as to the proper depth to set the 

 rhizomes. Shallow ,even surface plant- 

 ing has been advocated to avoid rot, 

 but I have found rot active in fully 

 exposed rhizomes as well as in those 

 covered with soil. In a mild climate 

 and with an old variety, I doubt if it 

 matters how shallow the rhizome is 

 planted, so long as the feeding toors get 

 down. Under our conditions at Ottawa 

 where during the past three winters we 

 have occasionally had temperatures of 

 18 to 25 degrees below zero without the 

 protection of snow, and where we have 

 in addition to the older varieties many 

 new ones whose hardiness is still under- 

 termined, I have found that a good 

 inch of soil over the rhizome affords 

 some protection without inducing con- 

 ditions favorable to rot. 



I QUESTION BOX | 



I V. E. GROVES } 



Rhododendrons 



"My rhododendron has had two buds on it 

 since last fall. These are not blighted. When 

 may I expect it to bloom? — Mrs. A. S., Niagara 

 Falls. 



Rhododendrons, like azaleas form 

 flower buds on the shoots made this 

 year, the buds opening next year. This 

 means that the buds on the plant will 

 mature during the early summer, and 

 if they are still firm, there is no doubt 

 about the opening to full bloom. After 

 blooming, all seed pods should be cut 

 off making it possible for new growth 

 in just the same way as previously 

 described for azaleas. 



Green Gage Plum 



"A clean, healthy Green Gage plum tree about 

 ten years old blossoms well but sets little fruit. 

 What is the reason and remedy?'' — F. B. L., 

 Longbranch, Ont. 



This is probably a case of self -sterility 

 If no other variety of European plum is 

 growing nearby, I would recommend 

 planting one for cross-pollination pur- 

 poses. Japanese or American varieties 

 will not fertilize the European sorts 

 which classification includes most of 

 the commercial varieties. — J. W.^^Crow, 

 B.S.A., Guelph. 



Keeping an Azalea 



"How shall I keep from year to year an 

 azalea purchased last month from the green- 

 house? Should I put it in the cellar after (lower- 

 ing for a rest?" Mrs. A. S., Niagara Falls. 



The azalea described should have no 

 resting period, but should be kept 

 growing all the year. All flower stems 

 should be cut off, and the new growth 

 will start away from the base of the 

 stems, and it is on the new shoots made 

 that the buds form for next years bloom. 

 For a time the plant should be kept in 

 a good position in the house, and be 



