Una sugerencia

En español no creo que tenemos una palabra para mulch (aunque el Colllins sugiere "mantillo")

mulch es una capa de material que se coloca sobre la tierra donde están sembradas las plantas para evitar (entre otras cosas) la evaporación del agua

Tu texto parece ser el título de algo, que lo que busca comunicar es que se aproxima la temporada de sequía y hay que intentar economizar agua.

Creo que para que se entienda, lo que hay que buscar es comunicar esta idea.

Algunas sugerencias: (ahora, hay que ver cuál es el propósito más específico de la frase: anunciar una marca de "mulch", economizar agua, consejos para el cuidado del jardín... Según eso es que debes elegir cómo traducirlo.)

lo más literal:
¡Se acerca un verano seco/árido! Proteja la tierra
(este serviría si el objetivo es ecológico, de ahorrar agua: y aprovechas el juego de palabras en español entre tierra-Tierra:

Economice agua
Cubra la tierra de sus plantas...

definiciones para mulch:

Any loose material placed over the soil to control weeds and conserve soil moisture. Usually this is a coarse organic matter, such as leaves, clippings or bark, but plastic sheeting and other commercial products can also be used.
www.thegardenhelper.com/dictionary.html

Any substance spread or allowed to remain on the soil surface to conserve soil moisture and shield soil particles from the erosive forces of raindrops and runoff.
www.nsc.org/ehc/glossar1.htm

a protective covering of various substances, especially organic; placed around plants to prevent evaporation of moisture and freezing of roots and to control weeds.
www.wef.org/publicinfo/newsroom/wastewater_glossary.jhtml

any material such as straw, sawdust, leaves, plastic film, or pine bark that is spread upon the surface of the soil to protect the soil and plant roots from the effects of raindrops, soil crusting, freezing, and evaporation.
www.trinity-trudy.org/coolstuff/vocab.htm

A natural or artificial layer of plant residue which aids in seedling germination by reducing the temperature fluctuations, holding moisture and holding soil in place.
www.calhouncountymi.org/Departments/DrainCommissioner/Defin...

Any nonsynthetic material, such as wood chips, leaves, or straw, or any synthetic material included on the National List for such use, such as newspaper or plastic that serves to suppress weed growth, moderate soil temperature, or conserve soil moisture.
www.ebfarm.com/Organic/Glossary.aspx

materials such as pine straw, wood chips, bark, and leaves that are loosely spread on the soil surface to reduce water loss and weed growth.
www.sfrc.ufl.edu/Extension/ssfor11.htm

material spread on the top of the soil to prevent erosion and evaporation of water.
www.rwater.com/glossary/gloss_mz.htm

Organic material, such as leaves or straw, spread on the ground around plants to hold in moisture, smother weeds, and feed the soil.
www.weblife.org/humanure/glossary.html

A layer of material spread on top of the soil around plants. Organic material such as shredded bark, compost or leaf mold retain moisture and insulate roots. Inorganic material such as black plastic suppress weeds and retain moisture in the soil.
www.rainyside.com/resources/reference/terms.html

leaves, straw or compost used to cover growing plants to protect them from the wind or cold.
www.nrdc.org/reference/glossary/m.asp

A protective covering that is spread on the ground around plants to inhibit evaporation and weed growth, control soil temperature, enrich the soil, or prevent the dispersal of pathogens. It may be organic material such as leaves, peat, or wood chips, or inorganic material such as plastic sheeting. (1)
ppathw3.cals.cornell.edu/glossary/Defs_M.htm

Any loose, usually organic material placed over the soil as a protective covering or for decorative purposes. Common mulches are ground bark, saw dust, leaves or straw.
www.boldweb.com/greenweb/glossary.htm

Organic or inorganic materials which are spread on the soil surface. Mulch slows down the evaporation of water from the soil, moderates soil temperatures, discourages weeds and beautifies the landscape.
www.compostinfo.com/tutorial/Glossary.htm

A layer of material placed on the soil surface to prevent weed growth.
ucipm.ucdavis.edu/PMG/glossary.html

to: The application of compost or other organic material to the soil for the purpose of reducing evaporation, fertilizing, or weed suppression.
www.regannursery.com/getting_started/rose_glossary.htm

A mulch is any material, either organic or inorganic, spread over the soil to protect it from temperature changes, water loss and weeds.
www.ottawa.ca/residents/healthy_lawns/lawns/links/glossary_...

layer of material, such as organic matter or plastic, applied to the surface of the soil to retain water and inhibit weeds.
www.ipmalmanac.com/glossary/index.asp

Protective covering, either organic or man-made, that is put over the ground to protect plants from freezing and drying out, and to retard weed growth.
www.nps.gov/miss/restoration/glossary.html

A material created by chopping/grinding leaves and/or wood into a fine, spreadable form that is less coarse and more workable. In the captive rearing of scarab beetles, mulch is made by breaking down decayed wood and leaves originating from deciduous hardwood trees, and mixing the two together to form a breeding/rearing substrate.
www.naturalworlds.org/scarabaeidae/moretopics/Scarabaeidae_...

Any loose covering on the surface of the soil, whether naturally occurring (eg, litter) or deliberately applied (eg, gravel); used to reduce competing vegetation, retain humidity, and protect against frost and heavy rain.
www.ccfm.org/ci/gloss_e.html

Lots of materials make good mulches. Any kind of well-decomposed organic matter will work: leaf mold, aged sawdust, and aged stable bedding. Shredded leaves, even when fresh, make good mulch. Mulch controls weeds, moderates soil moisture and temperature fluctuations, improves soil fertility and structure, reduces pest and disease damage, and can even improve the flavor of crops.
www.bayeradvanced.com/garden/glossary.cfm

Any of a number of materials, usually organic, that can be placed on the soil in a thick layer to retain moisture and deter weed growth. Plastic sheeting is also considered a form of mulch.
www.vivagarden.com/toolshed/terms.html

Covering on surface of soil to protect and enhance certain charcteristics, such as water retention qualities.
www.sonomamarinrcds.org/district-ssc/resources/glossary/glo...

Any material laid on the soil surface to conserve soil moisture, moderate temperature and/or aid in weed control. Wood chips, bark chips, and shredded leaves are examples of organic mulches.
www.treesny.com/trees_glossary.htm

cover with mulch; "mulch the flowerbeds"
a protective covering of rotting vegetable matter spread to reduce evaporation and soil erosion
wordnet.princeton.edu/perl/webwn

In agriculture and gardening, mulch is a protective cover placed over the soil, primarily to modify the effects of the local climate. A wide variety of natural and synthetic materials are used.
en.wikipedia.org/wiki/Mulch