The Secret to Improving Sandy Soil

, written by gb flag

An overwintering green manure of field beans to improve sandy soil

Gardeners coping with sandy soil daydream about sticky clay! Light, free-draining, quick to warm up in spring...sounds like horticultural heaven, doesn’t it? But those of us who have actually had to work with sandy soil know better. Sand undoubtedly has its plus points, but it has its challenges, too.

Fortunately, there is a simple way to alleviate some of the problems it presents – namely, poor fertility and a tendency to dry out fast.

How to Tell if You Have Sandy Soil

To work out what kind of soil you have you need to perform a soil test. It’s incredibly complicated and difficult to do, requires much training and effort, and is not for the faint-hearted. Are you game? Okay then, here’s what you have to do:

Take a handful of soil, dampen it, then try rolling it into a sausage shape. Sandy soil will crumble and fall apart. You’ll be able to make out the individual grains. Clay soil will stick together easily and can be rubbed to a dull sheen. Silty soils, which are rare, are often described as having a ‘soapy’ texture. (I don’t know. I’ve never seen it. They’re pretty rare!) Loam – a gardener’s nirvana – is somewhere in between.

And...well, that’s it. Have a cup of tea and put your feet up. You deserve it.

Sandy soil is gritty and falls apart easily

Turn Sandy Soil into Sandy Loam

Okay, so it’s not very scientific, but the test I’ve just described is good enough for most gardeners. If you want more detail, try the Jar Test.

The next step requires a little more work. Sandy soils are less fertile than other soil types, and more prone to drying out, because they’re made up of relatively large particles. This means there are cavernous gaps between the particles, making it easy for water (and water-soluble nutrients) to filter down through the soil, out of the reach of plant roots. We need to partially plug up those gaps and help the soil to hold on to water and nutrients.

So here’s how to do it:

Add organic matter.

It really is that simple!

Organic matter such as manure helps sandy soil to retain moisture and nutrients

Organic matter is a kind of cure-all in the garden. You can’t go wrong with organic matter. It will improve any soil type. Any organic matter will work to build soil structure and its ability to hold onto water. Compost and manure are preferred because they are rich in nutrients, which they drip-feed to your plants. Over time, they’ll also help to increase the pH of acidic sandy soils.

I won’t lie – sandy soils do need a lot of organic matter, frequently applied, to make a difference. The warmer your climate, the faster organic matter will break down, and the more often your soil will need replenishing. Start with at least two bucketfuls of organic matter per square yard each fall, added to the soil surface as a mulch where it will help to protect the soil from scouring rain and winds.

Keep notes on how well your crops fare (our free Garden Journal can help with this) and, if you feel they’re underperforming, up the frequency to twice a year. You could also try three bucketsful, or four. It’s worth adding more in summer if you can too. Grass clippings are a free, regularly available resource that help to reduce evaporation, and they’ll provide a modest flush of nitrogen to boost plant growth too.

After adding all that organic matter you really will need a sit-down and a cup of tea. What the hell – make it a beer!

Tap-rooted vegetables such as carrots can easily drill down through light sandy soils

Best Vegetables for Sandy Soil

Improving your soil takes several seasons. But even with the best will in the world, it will always be sandy soil at heart. ‘Work with what you’ve got’ is good advice! So let’s take a look at which vegetables naturally grow well in sandy soil.

Root vegetables are sandy soil superstars. Motivated by thirst, plants with long taproots like carrots and parsnips are perfectly designed to reach down into the moister soil that lies several inches below the surface.

When you’re itching to get growing at the start of the year, sandy soil is a plus. Warming up and drying out quickly, you’re more likely to have success with early sowings of vegetables such as lettuce and collards.

Potatoes tend not to develop scab in acidic sandy soils, but they are thirsty plants. Less water, more often is a good rule of thumb. This advice doesn’t just apply to potatoes, but all vegetables grown on this type of soil. The same goes for fertilizer. You might want to consider installing irrigation to gradually water and feed your plants.

Mediterranean herbs like lavender will positively thrive in light, dry soils

Mediterranean herbs were made for thin, dry, sandy soils. This is one situation where improving the soil with organic matter is not required. Lavender, thyme and rosemary will cope just fine – in fact they’ll be happier – with a low-fertility bed that never becomes waterlogged in winter.

Most shallow-rooted plants tend to dry out very fast on sandy soils, and brassicas will struggle in the loose, acidic conditions. That’s not to say they can’t be grown, but they will need much more attention than plants that are more suited to growing on sand.

The best vegetables to grow on sandy soil are those that can be grown right through the winter, because they help to bind the soil with their roots and protect it from wind, rain and snow with their leaves. Or sow an overwintering green manure. Even a carpet of weeds will do. What better excuse for delaying that final autumn weeding session?

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Show Comments


"My sandy soil doesn't drain easily. The water lies on top and its almost looks greasy. When I plant in it, the plant roots seem to suffocate once the water sinks in after awhile. What must I do?"
Annette Hansen on Saturday 6 March 2021
"It sounds like the soil may have become compacted. If it's very sandy all the particle sizes will be the same, and this can make it prone to locking together so water doesn't drain through. I'd dig in plenty of compost or other organic matter, which will give a range of particle sizes and should help water to move more freely through it. "
Ann Marie Hendry on Tuesday 9 March 2021
"I think your secret to fixing sandy soil is missing an important ingredient and that is mixing clay into the sand. You can use Kaolin clay which disperses better than Bentonite clay according to research. There are some premixed solutions out their with kaolin clay like soilsolver and garden centres like greenlifesoil have clay mixes for sandy soil. Clay content can stop the sandy soil becoming water repellent once in enough quantities according to Professor Dan Carter. Over 10% is good I believe. Then your organics work well with the water retention and nutrient holding capability of the clay, combined into the sand soil. Thanks for your article. I'll be adding more organic matter too."
Dale Carter on Thursday 9 December 2021
"Hi Dale. Adding clay is definitely a possibility but I reckon you'd need large amounts to make much of a difference, which could become expensive. Incorporating organic matter as well sounds like an ideal plan. Good luck!"
Ann Marie Hendry on Thursday 9 December 2021
"Hi there. Thanks for those great tips about what to grow in sandy soil. I've moved to the beach and have plenty of dwarf trees and berry bushes and veg boxes to keep me in food. I'm loving the change from an exposed rocky site in Wellington - weeds come straight out. I found your article while I was Google searching for a book on growing veg in sandy soils. I didn't find one. Do you know of any book that covers this topic? My grandfather had a prolific half acre veg garden at Himatangi Beach and he said you could grow anything in sand if you could get it to retain water - organic matter."
Carol on Tuesday 1 February 2022
"I agree with the comment about adding clay, or something with fine particles, and as long as it's mineral, not organic. Otherwise you're putting in organic matter for the rest of your life, which is a band-aid not a solution. In warmer climates organic matter in sandy soils will dry out and will repel water, making the problem worse. The long-term solution would be mineral."
Greg SJ on Saturday 25 June 2022
"Hi Greg. With any type of soil it's important to add organic matter regularly, because as well as gradually improving the soil's structure it also helps to add fertility, encourage beneficial soil life, and (when added to the surface as a mulch) reduces evaporation and minimises weed competition. This isn't a band-aid solution - it's key to soil health over the long term. So while something like Kaolin or bentonite clay can be useful as a one-off amendment, it shouldn't be used as a replacement for organic matter. When you take from the soil, you have to put back."
Ann Marie Hendry on Tuesday 28 June 2022
"it was helpful"
mutale natasha on Sunday 2 October 2022
"manure strait into your garden has draw backs; it brings in every different weed seeds in the animals pasture ; and also can bring bacteria that can make you sick; best to hot compost manure then add to your soil, imho "
Neil H on Monday 23 January 2023
"Absolutely Neil. Manure should normally be composted for several months before adding to the garden."
Ann Marie Hendry on Tuesday 24 January 2023

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