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Garden Q&A: Add compost to soil twice a year

| Saturday, March 16, 2013, 9:00 p.m.
A raised bed vegetable garden
Jessica Walliser
A raised bed vegetable garden

Q: I have two 8-foot raised beds that I use for vegetables. Even though I add compost in spring, turn the soil over, and have it tested every few years, I think the soil is tired. Can you suggest some things that a veggie gardener can do to stimulate the soil before the planting season to ensure the crop is robust? I guess in tandem with that, what should we continue to do through the growing season? My next dilemma is in the same raised beds — I seem to have acquired a huge amount of pill bugs in the last two years. You don't actually see too many when the soil is at rest, but just turn it over and there are literally thousands of them in any given spot. Supposedly, they are not doing any damage, but I have found them eating the leaves, roots, etc. Should I be concerned and try to get rid of them, and how?

A: Regular additions of compost are, hands-down, the best thing you can do to help rejuvenate raised beds. Because you are growing heavy feeders such as vegetables in the same soil year after year, it stands to reason that the soil will become depleted in many nutrients over the years. You are requiring a lot of the soil in a raised bed, and it's only fair that you replenish what the veggies remove as often as possible. I always suggest twice yearly additions of organic matter to raised beds. This should be in the form of finished compost, aged horse or cow manure, or leaf mold (or leaf compost) applied 1 or 2 inches thick across the entire surface of the soil in spring and then again in fall.

Because you bring up the pill bug issue as well, I'm inclined to think that perhaps the compost you've been adding is not “finished” — meaning it has not fully broken down. We gardeners are notorious for applying our homemade compost before it is fully cooked, simply because we are excited that we made it ourselves and we need to empty the compost bin to make room for more yard waste.

It is important to make sure none of the original pieces of yard waste are recognizable in the finished product; that's one of the ways to know it is “finished.” Pill bugs feed on partially decayed organic matter (including unhealthy/dying plant roots and shoots), and if the compost you are applying isn't fully decomposed, they'll make a lunch date out of it in a heartbeat.

I also would suggest you alternate your organic matter sources. This helps ensure a balanced diet, so to speak, and prevents any nutrient imbalances within the soil. I suspect it will also help with your pill bug problem.

I'm thankful to hear that you have your soil regularly tested. I've covered the importance of this many times before in this column, and it is exceedingly important in the contained environment of a raised bed. Especially the soil pH.

And one last thing you can and should be doing through the season to stimulate your plants and your soil: use liquid fertilizers. I'm not talking about the chemical blue stuff, but rather water-soluble fertilizers that will introduce not only the primary plant nutrients, but also trace nutrients, vitamins, amino acids and natural plant hormones that all serve to boost production and help maintain soil and plant health. Once or twice a month throughout the growing season, apply liquid kelp, fish emulsion (which stinks), fish hydroslate (which doesn't), compost tea, or other similar organic liquid fertilizers with a sprayer or a watering can. The difference they can make is pretty incredible.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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