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Wednesday, May 20, 2009

Soils for the garden and for potting

No glamorous photos today. In the last two days I've had enough conversations about garden soil to convince me that many people are confused over what to use and where to use it.

I'll begin by letting all of you know that I do not have a degree in horticulture and have never taken a formal class in soil science. What I do have is 23 years of experience as a home gardener.

The soil you need for pots and containers is greatly different than the soil you need for bedding plants in the ground. In containers plants need soil that won't dry out too fast, is heavy enough to keep the pot from falling over on a windy day, is light enough for the roots to grow and will also feed the plants. That's a pretty tall order!

For my pots, I mix 2 parts of potting soil with one part of compost. I also throw in a good sized helping of shredded leaves and most importantly, try to mulch the plants to keep the soil from drying out too quickly. The added weight of compost (top soil works too) keeps the pots from being too light. You can also add fertilizer to this mix, a slow release fertilizer works well, I add milorganite to my pots here as a bonus.

Buying large bags of potting soil and adding them to your garden is a waste (in my opinion). You are much better off buying bags of compost or having a yard or two of compost delivered to your home. Last year I ordered a mix of compost and aged horse manure. I made the mistake of ordering too much at one time (in order to save on the delivery charge). This year I'll order less and take my chances.

If you can find aged horse manure, go for it! Here on Long Island horse manure is readily available from local horse farms. Cow manure is not readily available in my neighborhood but if you have it where you live it's just as good as horse manure.

Last but not least is mulch. Mulch is an organic (hopefully!) product that you put on top of the soil to help slow the germination of weed seeds, help water retention in the ground (keeps it from drying out), add nutrition to the soil and just to help the garden look neat and clean.

I'm not a fan of the huge deliveries of mulch, in many cases it's died and I can smell the chemicals while I'm walking past a house that has freshly mulched beds. At our house we save our leaves in bags over the winter and then shred them to use as mulch. From past experience I can tell you that the worms will love you for mulching with leaves. Worms are great for the garden, they help aerate the soil and add more nutrients (worm poop is a great soil booster).

One last tip on mulch, for spring mulching I wait until the soil has warmed up (not yet in our area) and for winter mulching I wait until the soil has frozen. The reason is that in summer you want to use the mulch as a blanket to keep the soil temperature consistent and in the winter you want to keep the plants from heaving during frost/thaw periods. If you mulch a winter soil while it's still warm, you will invite lots of burrowing creatures (voles, chipmunks, moles and so on) to your nice warm beds.

Today looks to be glorious outside so I need to get dressed and get out there to start digging and potting. Also have to plant some veggies :-)

Happy gardening!


  1. Hi, I have a beginner's question. Can I put in grass clippings instead of shredded leaves.


  2. Hi Chandrika,

    Grass clippings are an excellent way to boost your compost heap but not a recommended way to mulch your garden or to add to potting soil. Grass clippings get quite hot when they start to decompose.

    I always wish for grass clippings here, we have a lawn service and they don't catch the clippings. If possible, find a corner where you can pile your clippings. They'll quickly breakdown and then you can use them in the garden.

    Of course there's always the case where people break the rules. My dad used to pile his grass clippings all around the perimeter of his garden and then grow his tomatoes in them. He had the best tomatoes around!

  3. Thanks a lot Melanie !!!

    For now, we'll just leave the clippings on the lawn.


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