Your March Tropical Homestead Checklist

A kilowatt-hour is an amount of electricity, about what a small heater uses in one hour. After months without rain, dust has had plenty of time to settle on the glass again since February's wash.

Give it the same bucket-and-brush clean from the ground, early on a cool morning. In March heat the timing matters most: cold water on hot glass can crack it, and scientists call that "thermal shock".

Never walk on the panels. Our guide to cleaning solar panels explains what to use and what to avoid.

Solar panels love sunlight but hate heat. Most lose about 0.2 to 0.5% of their power for every degree above 25 °C, the temperature they're tested at.

That number is called the temperature coefficient. One example panel with a coefficient of 0.41% loses about 16% of its power when its cells reach 65 °C. On a hot, sunny roof, that happens easily.

You can't switch off the heat, but you can let air flow. Panels mounted with a gap underneath stay cooler than panels lying flat on a hot roof, a bit like a fan cooling a laptop from below.

The same heat wears out batteries, and March is when January's shade rule gets its real test. Check that the battery corner is still the shadiest, best-ventilated spot you have, never a closed metal box in the sun.

By March many tanks are low and the rains are still weeks away. So decide now what water is for.

Drinking and cooking come first, then washing. The garden gets what's left, plus used shower and sink water where it's safe. Our guide to greywater shows how to reuse it without making anyone sick.

Plants drink more now, too. The University of Guam's farm advisers say plants lose water fastest in the dry season, when humidity and rainfall are low and the wind is brisk. Cutting back a little now beats running dry in May.

Here's a trick that costs nothing. Scientists call it SODIS, short for solar water disinfection.

Fill clear plastic bottles of 2 litres or less with clear water and lay them in full sun. Sunlight's invisible ultraviolet rays kill the germs. The SODIS guide from the Swiss research institute Eawag says 6 hours of full sun is enough, or 2 days when more than half the sky is cloudy.

Use PET bottles, not PVC. SODIS kills germs but does not remove chemicals.

Drink straight from the treated bottle. Pouring it into another jug can let germs back in.

It only works with clear water. Cloudy water needs filtering through a cloth or settling first. Our guide to off-grid water filtration compares SODIS with boiling, filters and UV lamps.

The hottest hours are for resting, not digging. The CDC, the US health agency, advises keeping outdoor work for the morning and evening, and resting often in the shade.

It sounds lazy, but it's safety. Heat stroke is when the body can't cool itself anymore. The CDC says body temperature can then climb to 41 °C or higher within 10 to 15 minutes.

Confusion, a very hot body and passing out are warning signs, and that's an emergency: call for medical help and cool the person down right away.

A house heats up through its roof, walls and windows. Shade on the sunny side, light colours and closed curtains in the afternoon keep the sun's heat outside.

Our guide to off-grid cooling shows where heat sneaks into a house and how to stop it without burning battery power.

Last year's harvest of maize, rice and beans is still in the store, and the heat makes this a good time to check them.

The World Health Organization says to throw away grains and nuts that look mouldy, discoloured or shrivelled. Some moulds make poisons called aflatoxins that can damage the liver, and you can't cook them away.

Insects are the other enemy, and airtight bags help here.

When a bag is sealed tight, the living things inside use up the oxygen, and most insects die. Our guide to off-grid food preservation covers drying and storing food without a fridge.

So what can you plant in March in the tropics? In many tropical climates this is the hottest, driest stretch of the year, so whether you plant at all depends on your tank. The honest answer is: less than in January, and only what your water can keep alive.

The cool-season crops are mostly done. Lettuce, cabbage and broccoli liked the cooler months, and an old University of Hawaii garden guide already said to swap cabbage for pak choy in hot weather.

Some vegetables and fruits do thrive in the heat, though:

The catch is water. The Guam guide says: if possible, never let your plants wilt, because even on-and-off dry spells cut how much they produce. That same Darwin gardener, Leonie Norrington, waters her tropical greens at least once a day, and twice when it's really hot.

Sweet leaf is the tough one. She says it stresses in the hot weeks before the rains without water, but water once a week and a layer of mulch keep it fine. Its tips taste like fresh garden peas.

Cucumbers and pumpkins love warmth too, but the Hawaii guide warns they take a lot of space, and melon flies ruin many of the fruits unless you bag them.

So keep March plantings small, close to the kitchen and its washing-up water. Bigger sowings wait for the rains, which are about two months away for many tropical homes.

Until then, sort the seeds you saved in October and February, and keep them dark, cool and above all dry. Stored like that, last year's packets are probably still fine. Our off-grid garden guide covers soil, water and how much space a family needs.

Heat speeds up a compost heap, but it also brings flies and smells to fresh scraps.

The fix is simple. The US Environmental Protection Agency says to always cover food scraps with 10 to 20 cm of dry leaves or other "browns". That's dry material like leaves, straw and cardboard.

And keep the heap damp, like a wrung-out sponge. Our guide to home composting explains how to get the mix right.