Garden Drainage and Watering Alpine Garden Plants

Garden Drainage for Alpine Garden Plants

There should be no need to fit garden drainage tiles to most raised sites for alpine garden plants, unless the soil is heavy clay or the water table is high.

garden drainage

The water table is the level to which water rises in the ground under normal conditions. If this is just below the surface of the soil, then drains are essential; if above, then you should take up water gardening not alpine plant growing!

To check for a high water level in the soil, dig a hole at the lowest point in the garden. Any water appearing in that hole will indicate the level of water.

Where the water table is just below the ground, flooding can obviously occur, so choose the highest ground possible and fit 30cm by 10cm (12” by 4”) tiles to run the water off.  Lay these just above the normal water table level by hollowing out the soil to fit the tiles and no more; then put a layer of gravel on top of the tiles.

Provided there is a slope or at least a fall of 1 in 200 for the drains and somewhere for the water to drain to, the whole garden can be drained without any problems, see figure 2.

Drainage Rock Gardens fig. 2


Garden Drainage for Clay Soils

The same principle applies for tile draining on heavy clay soils but the depth to which the tiles can be laid is greater.  Note, if they are buried deeper than 60cm (2′) at any point they will be ineffective. It is important not to lay more than 10cm (4”) of gravel over the tiles or this will be disturbed by cultivations.

A similar procedure is carried out when building drains under a lawn but in this case the gravel should be covered by fine nylon mesh to prevent soil being washed down to the gravel and thence to the tiles. There is no need to drain more than 22cm (9”) below the grass level.

These details for drainage are intended for the garden as a whole and cover all sites and constructions except rock gardens.

Watering Alpine Plants

Methods of watering are best kept as simple as possible, with a sprinkler, preferably with a spike in the base, on the end of a hosepipe, for example.

Much more important, however, are the questions of when and how often to apply the water.

All categories of plants can be watered by the same sprinkler by watering to suit the middle range plants when one or two are just beginning to show signs of flagging. Alternatively, water just those plants requiring water, by hand.

In their first season in the garden, alpine plants will require more watering than successive seasons so watering by hand is often best. Use a sprinkler for the successive seasons but less often, in order to encourage the roots to grow downwards rather than sideways.

When plants are in need of water, those with soft foliage remain turgid or firm in the leaves but when too dry, they droop or flag.


23. July 2010 by Dave Pinkney
Categories: Alpines, Gardening Ideas, Rockery Garden | Tags: , , | Comments Off on Garden Drainage and Watering Alpine Garden Plants


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