12 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
much the same on an average for the thirteen years as for the four. 
This list, therefore, may be used as a guide to the choice of 
varieties to plant together for cross-pollination purposes, since the 
relative order of flowering varies but little from year to year. 
The number of days in which varieties remain in bloom varies 
according to the season, and undoubtedly some varieties, like * Lane's 
Prince Albert ' and ' Newton Wonder/ remain in bloom in any season 
some few days longer than varieties like ' Lord Derby ' and ' Beauty 
of Bath/ which usually have a comparatively short period of flower- 
ing. On an average, eighteen days may be regarded as the normal 
flowering period of varieties, this being from the time of the first flowers 
opening until most of the flowers are over. 
Individual flowers have an average life of about a week. In cold 
or very boisterous weather this would be appreciably lessened, whilst 
in fine dry weather it might be extended by several days. 
The flowering periods of the comparatively few commonly grown 
varieties seldom coincide exactly, and, indeed, from the time of the 
first blossoms opening on the earliest flowering variety to the falling 
of the blossoms of the latest there is a period of some six weeks or so ; 
and since the average length of time over which any variety is in 
flower is eighteen days, it will be seen that the haphazard choosing 
of varieties for " intermixing " may prove of little use. 
For really effective cross-pollination between any two varieties, 
the time of flowering — from two days before full bloom until seven 
days after full bloom — of each should overlap ; anything less than 
this may mean that in a particular year it would not be possible for 
effective cross-pollination to take place. 
The relative order of flowering varies so little each year, however, 
that if two varieties are planted together, the flowering periods of 
which overlap within two days before full bloom and seven days after, 
cross-pollination should take place in any year. 
In the chart on the opposite page the order and effective flowering 
period of ten well-known and commonly grown varieties is given, to 
illustrate this point. 
The crosses show the time at which each variety may be expected 
to come into full flower in relation to any other, the days' difference 
being noted on the top line ; the lines opposite each variety represent 
their effective flowering period — two days before full bloom and seven 
days after, — the table being made from figures obtained over a period 
of thirteen years at Wisley. 
From this chart it may be seen that if two varieties, such as 
'Warner's King' and 'Newton Wonder,' were planted together, by 
the time the ' Newtons ' were in full flower the blossoms of 
' Warner's ' would be some nine days past full bloom, and although 
even then cross-pollination would take place to some extent, it would 
not be so effective nor likely to induce such good settings of fruit as if a 
row or two of ' Worcester's/ ' Cox's/ or ' Bramley's ' were interplanted, 
which would ensure the effective cross-pollination of both. 
