Close plantings help conserve moisture in the long, hot summer

During the long hot period between spring and early autumn anything one can do to shade the surface of soil is extremely beneficial.
It delays or, even better, prevents the surface from hardening and capillary evaporation pores from forming and descending into the soil mass.
In the book now available from Amazon books ‘How to use less water in your garden’ some 35 ways of mulching and improving existing mulches are presented for you to use as a check list of what to try next.
One form of mulching that is often overlooked is live ground cover plant mulching, i.e. the close planting of plants so that their foliage touches and overlaps. This can also be referred to as carpet planting.
There are several important benefits to plant mulches:
• It keeps the surface of the soil shaded and therefore reduces the chance of it being baked like a brick by the sun and reducing the losses of moisture by capillary action through hard baked layers of soil.
• It can be permanent 365 days a year and does not degrade or rot down in time.
• The germination of weeds is discouraged as they would be in shade, and if some do germinate and start to grow they are likely to be stunted by the dark and soon die or chase up to the light and then die when the weak growth dries up in the sun.
• There is an increased chance of low growing branches touching the soil and self rooting. This leads to extra supplies of moisture, extra roots to hold soil banks together and the production of daughter plantlets that can be severed from the parent plant and dug up for transplanting elsewhere.
• Provision of shade for beneficial lizards, toads, frogs and earthworms. The shade might however also attract snails and slugs but if this is seen to occur ecological snail/slug bait such as Neudorff’s Ferromol Anticlimacos can be sprinkled beneath the dense leaf cover to do its job invisibly.
• Provide natural insecticide effects. For instance planting rose or lemon scented graveolens  geraniums that are not attacked by the geranium moth amongst plants of other varieties that are. Or surrounding beds with a row of thyme plants that have a mild insecticide effect.
• The creation of mass colour effects, both masses of one colour or a large kaleidoscope mixed colour effect.
As discussed in Chapter 2.6 of ‘Your Garden in Spain – From planning to planting and maintenance’ we see the process of deciding on plantings as ‘painting with plants’, the predominant colour of gardens being green ranging from bright yellow greens to more sombre, to blue greens.
When designing carpet mulches the plants close planted can be:
• All of the same type such as the circle of trailing purple lantana under our Bird of Paradise tree and a large bed of lavender.
• Mixes of different types for colour effects such       as our densely-planted rockery.
• A mix of plants that are in leaf and in flower at different times of the year. For instance a mass of flowering spring bulbs under the bare pruned skeleton of branches of a lantana bush, which will be smothered when adjacent lantanas leaf up and intermingle to create a continuous summer ground cover.
• A mix of long-term survivors and sacrificial plants. For instance, where slow growing plants like low growing spreading junipers and the spreading variety of rosemary are to be the long- term ground cover, herbaceous sacrificial plants can be planted in the initial gaps  recognising that they will be smothered and die in time.
Carpet planting can also be used when growing vegetables such as lettuces in the open ground or on a growing table on an apartment terrace.
Interesting designs can be created by close planting a mix of the various green and red leafed varieties.
© Dick Handscombe www.gardenspain.com
July 2015