The best time to garden by the UV index

Ask most gardeners when the best time to garden is, and they will tell you "when it's cool". That makes sense for comfort. But for your skin, the number that matters is not the temperature. It is the UV index. Here is how to use it to plan your time in the garden, in plain terms.

Temperature and UV are not the same thing

UV is the part of sunlight that burns and damages skin. You cannot see it, and you cannot feel it. The warmth you feel on your skin is a different part of sunlight.

Cancer Council is clear on this: temperature does not affect UV levels. UV can be just as high on a cool day as on a hot one, especially when the sky is clear. Thick cloud filters UV well, but UV gets through thin cloud. So a mild, breezy spring morning can still carry high UV, even though it feels lovely.

That is why "when it's cool" is a good rule for comfort, but not a reliable rule for sun safety.

What the UV index numbers mean

The UV index is a simple scale. Cancer Council groups it like this:

The key number is 3. Cancer Council says that whenever the UV index is 3 or above, you should use the five SunSmart steps: slip on clothing, slop on SPF 50 or higher sunscreen, slap on a broad-brimmed hat, seek shade and slide on sunglasses.

How to check the UV for your garden

You do not have to guess. There are easy, free ways to check:

• The SunSmart Global UV app. Free from Cancer Council. It shows live UV levels and the "sun protection times" for where you are, and can send you an alert when UV reaches 3. Find out about the app.
• ARPANSA's live UV readings. ARPANSA measures UV in Australian capital cities and publishes it in real time. See today's readings.
• The weather forecast. Cancer Council notes the UV index is in the weather pages of daily newspapers and on the Bureau of Meteorology website.

The "sun protection times" are the hours when the UV is forecast to be 3 or above. Plan your heavy jobs either side of them, or plan to cover up well during them.

In the US? The US EPA publishes a daily UV index forecast for your location, and the SunSmart Global UV app works worldwide too.

So when is the best time to garden?

Cancer Council says UV is usually at its peak between 10 am and 4 pm. That gives a simple rule of thumb:

• Early morning is usually the best time. It is cooler, and the UV is lower. Great for weeding, digging and anything that keeps you bent over for a long time.
• Late afternoon is the next best. Good for watering, light pruning and tidying up.
• The middle of the day is for short jobs, shady jobs, or jobs in the shed.

But use the app, not just the clock. Cancer Council says UV is higher in summer than in winter, but it is there every day of the year. It also varies across Australia, so it can be higher in one place than another on the same day. The app tells you what today is really like where you are.

Plan your jobs around the UV

A bit of planning lets you get everything done without spending the whole middle of the day in the sun.

• Long, bent-over jobs (weeding, planting out, edging): early morning.
• Jobs you can do in shade (potting up, sorting seeds, cleaning tools): middle of the day, under a tree or a verandah.
• Quick jobs (watering, picking herbs, checking the veggies): any time, but still cover up when the UV is 3 or above.
• Big jobs (mulching, hedge trimming): break them into two or three shorter sessions instead of one long afternoon.

Cover up when you cannot avoid the peak

Life does not always fit around the UV forecast. When you have to be out in the middle of the day:

• Hat: a broad brim of at least 7.5 cm, as Cancer Council suggests. Your neck points at the sky when you are bent over.
• Arms: a long-sleeved shirt, or UPF 50+ sun sleeves with your usual shirt. UPF is a rating for fabric; UPF 50+ means it blocks 98% or more of UV. IceRays fabric was tested by ARPANSA in 2015 (black sample) and rated UPF 50+. See what the test covered (PDF, opens in a new tab).
• Hands: gardening gloves.
• Face, ears and neck: SPF 50 or higher sunscreen, put on before your hands get dirty.
• Shade and water: take breaks somewhere shady, and keep a drink close by.

Sleeves are handy here because there is nothing to reapply with grubby hands. They are sun cover only, though, and not protection from thorns. Our page UV vs thorn protection, honestly explains the difference.

Your weekly garden routine

1. Check the week's UV and weather in the app on Sunday night.
2. Put the long jobs on the mornings with the best forecast.
3. Keep your hat, sleeves, gloves and sunscreen together by the back door.
4. Cover up whenever the UV is 3 or above, even for "just five minutes".
5. Wash your sleeves as the care label says, and put them back with the kit.

Keep reading

• Gardening in the sun: how to cover up without overheating
• UV vs thorn protection, honestly
• Sun sleeves for gardening
• The UV index for Australians
• What UPF 50+ means

Want a pair by the back door and one in the shed? The IceRays 4-pack is AUD 120 for four pairs, or $30 a pair. That saves $31.80 on four singles. One size fits all adults.