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Dish the dirt! What's your soil type?

It feels a little odd to be saying this with the August sun beating down on us, but it's a fact: Fall is just around the corner!

The other day I saw a string of orange school buses and suddenly was struck by the thought that they are a harbinger of the fall colors that lie just ahead!

Fall can be the most important season in the life-cycle of your landscape, and mid- to late-August is the ideal time to do some pre-fall "P and P" ... planning and preparation.

If you're looking for some inspiration, most supermarkets carry gardening magazines, and you can also make a "virtual visit" to a huge number of excellent resources on the Internet, where you can find pictures, descriptions and planting advice for your growing zone. I'm always happy to offer some suggestions if you send me e-mail at [email protected] and you can find several articles and previous columns about landscape planning at my web site www.landsteward.org Many mail-order and online suppliers are taking orders now for fall delivery, and it's a good idea to order early rather than miss out on the plants you had your set on!

When it comes to preparing for fall planting, one often overlooked issue is soil. Before you plant anything, it helps to know what type of soil you are dealing with. From time to time, it's useful to have a thorough analysis of your soil carried out. You can have this done by your local university extension service for a small fee. You need to be aware that it often takes several weeks to receive your results so if this is something you want to do, it is advisable to do it right away.

Can't wait? Many garden centers and online suppliers sell soil tester kits which give you a useful idea of the pH balance of your soil. A pH test reveals the acidity or alkalinity of the soil, allowing you to adjust as necessary. Most plants thrive in near-neutral pH conditions, but some plants (such as some blueberry varietals) like a slightly acidic soil.

The type of soil can make a big difference to the success or otherwise of your planting. There are four basic soil types: sandy, silty, clay and loam.

Sandy soil is pleasant to dig as it is light and airy. However. It is unable to retain a great deal of moisture or nutrients.

Silty soil, as you might guess from its name, is often found in and around river beds. Poor drainage is often a problem when your soil is silty.

Clay soil will usually form a ball when you squeeze a handful. It feels heavy and its close texture can prevent needed nutrients reaching plant roots. Poor drainage is another problem!

Loam is the stuff that great landscapes and gardens are made of! Loam, like Goldilocks third bowl of porridge, is "just right"; the perfect balance of sand, silt and clay, with a healthy percentage of organic matter.

There's a fairly simple way to discover what type of soil you have. Dig down a few inches below the surface and get a small scoop of soil. Put it in an old quart jelly jar and add about two cups of water and a little squirt of dishwashing detergent. Put the lid on and give it a thorough shake as if you were making a "real" dirty martini! Then let it stand for a day or so.

The soil will settle in layers from the bottom up in this order: sand, silt, clay. What proportion of your "cocktail" is made up of each layer? The ideal mix (or loam) is two fifths sand, two fifths silt and one fifth clay.

However, if the layer of sand accounts for half or more of the total, you have sandy soil. If the second layer is more than half of the total, you have silty soil. And if the top layer is more than a quarter of the total, it's a safe bet that you're dealing with soil that leans towards clay.

Once you know your soil type, you can adjust it by adding minerals, fertilizer or organic matter as needed. Or you can accept your soil for what it is and select trees and shrubs that are most likely to grow successfully in those conditions. In a future column I'll look at some ways to improve your soil. Until then, happy planning!

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to [email protected] and for resources and additional information, including archived columns, visit www.landsteward.org often.



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