Another important matter is that a pergola or green alley, in the usual sense, should never wind or go uphill. It is not intended by this that shading coverings cannot be used in such places, but that they would want especial design, and it is altogether a matter of doubt if these could not be much better treated in other ways.
The circumstances of different gardens are so infinitely various that it is impossible to lay down hard rules; only general rules can be given and exceptional circumstances dealt with by exceptional treatment.
Green alleys require some attention. In winter the oldest of the wood must be cut out to make room for the young growth, and when this is lengthening vigorously it must be carefully laid in.
If the alley has an iron framework, which is necessary when such strong growing things as Wistaria are used, this may be clothed during the first few years, until the Wistaria is growing strongly, with annual climbers such as _Cobæa scandens_, _lophospermum_, _Mina lobata_, and even varieties of the large-flowered Clematis, which must be removed when the Wistaria covers the alley.
[Illustration: _OLD APPLE WALK (Helmingham Hall)._]
Very charming alleys are sometimes formed of fruit trees--Pear, Apple, Cherry, and Plum making delightful spring pictures, and almost as much so when in fruit in autumn. Where fruit and flower are desired every shoot must be exposed to sun and air. When densely shaded by other growths the wood does not ripen, and therefore flowers badly, if at all.
One's enjoyment of the garden would be greatly increased if the orchard, which is so often thrust away into a remote corner, were brought into direct communication with it. How easily the trimmer lawn spaces might lead through groups of flowering shrubs to the rather rougher grassy orchard. How naturally the garden Roses and masses of free-growing Cluster Roses would lead to their near relations, the Pears and Apples and other fruiting trees of the great Rose order.
There is no need to make a definite break between the two; it is all the better not to know where the garden ends and the orchard begins. Towards the edge of the mown lawn there may already be trees of the Red Siberian Crab and the handsome Crab John Downie, and the pretty little Fairy Apple; while the nearer orchard trees may well be wreathed with some of the free Cluster Roses, such as Bennett's Seedling or Dundee Rambler.
