Abundant Harvests - garden info,  water wisdom

Hydrophobic: What to do when your soil is too dry

You pour water on your garden soil but it rolls right off the surface. It won’t soak in!

Or, after you water, the soil looks dark brown and damp, but when you poke your finger into it (the one-finger test), only the top crust is dampened and everything is dry, dry, dry beneath.

If you live in dry Southern California, you’re undoubtedly familiar with this phenomenon, known as a hydrophobic condition.

I’m not sure what fear/phobia has to do with it. In the sandy, it’s-really-a-sand-dune soils of Westchester (L.A. 90045, near LAX), hydrophobic conditions are more and more frequent.

Used to be we’d see this phenomenon beginning in, say, June, continuing through the summer, and not letting up until the first rains of autumn. Ahem. These days that “first rain” might be the “only rain,” and it might not arrive til December. And hydrophobic conditions can easily appear in January.

Welcome to climate change. Welcome to aridification. You have no choice but to get used to it.

What can you do when your soil behaves like this? Here are some things that work for me:

Add compost

Compost is things that used to be plants, mostly decomposed. Compost acts like a sponge in your soil, soaking up water and holding it for plants and soil critters to use later.

If your compost supply feels dry to the touch, mix water into the compost before you begin to use it. You want it to feel like a wrung-out kitchen sponge.

If you’re planting a new garden, mix the moistened compost into the soil.

If you’re working with existing plantings, dig out small plugs — say, the size of 1-pint yogurt tubs — between your plants. Shovel compost into the holes you’ve created.

Build moats

Use existing garden soil (not mulch) to surround your plant with a rimmed basin. When you water, this basin or moat will prevent runoff. It will hold water above the plant’s rootball until the water has a chance to soak in.

How big a basin? As wide as the plant’s rain shadow.

What’s a rain shadow? Imagine a gentle rain falling onto a plant or tree: the circle of soil that the plant shelters from the rain is the plant’s rain shadow. This circle is defined by the furthest reach of the plant or tree’s branch tips.

Cover your soil

Simply lay mulch on top of the surface of your soil. The mulch will soak up water and hold it for the plants and soil critters.

Also, the mulch helps keep the top layer of surface open, friable. That helps water penetrate into the soil.

For veggie plants, mulch with crumbled dry leaves, chopped-up garden trimmings, grass clippings (without seedheads), straw (not hay), or shredded newspaper.

For perennials and trees, use tree chippings, or chipped-bark mulch. Remember to leave a small mulch-free gap against the trunk of all trees — because mulch against tree bark can cultivate plant pathogens.

Soak the hole

If you’re adding a new transplant to your garden, habitat restoration expert Nicholas Hummingbird recommends you dig the hole, then fill the empty hole with water and let it soak in. Repeat this five times. Then tuck your plant into its new home, make a basin, and water it in from the surface.

This tip is not applicable to existing plantings.

Water in the evening

When you water after 4pm, the water has all night to soak into your soil, before the searing rays of the SoCal sun begin to evaporate it.

When you water late in the day, your plants have all night to uptake the water, to refresh them before that sun gets to its peak.

It’s not just LADWP drought-buster regulations — it’s good gardening practice!

Water with a fine mist

When I’m having a tough time getting water to soak into my soil, especially in my vegetable garden, I turn to those hose-end attachments that produce the very finest mist. Somehow it seems like that really fine mist begins open the soil surface in a way that large-scale delivery of water doesn’t.

I’ll use the fine-mist attachment (in the evening), and I’ll allow it to soak in. Then I’ll water again, with the hose-end attachment that delivers more water.

Ultimately, you’re trying to re-hydrate your soil. This fine-mist tip is about water delivery, but you need to use it with the other tools like compost & mulch so that your soil can hold onto the water.

Try ollas

Ollas are unglazed clay pots which are buried into the soil of your garden. You fill them with water and they gradually sweat water into the surrounding soil.

Ollas are a good thing to insert into beds which chronically dry out. Ollas deliver the water slowly, so it soaks in. And they deliver the water deep, into the root zone.

The advantage of cheap DIY ollas is that you can afford to place several of them in a given garden bed.