Jeff Lowenfels: Helpful tips for novice gardeners on starting seeds

Jeff Lowenfels
Erik Hill

More than a few new gardeners have asked for a word or two on starting seeds: What kind of soil? How to water seedlings? Things like that. So, let me take a crack at a few answers this week.

First, starting soil is absolutely key. Back in the day it was standard practice to use sterilized soil for starting seeds and transplanting them. My dad even inherited my grandfather's professional soil sterilizer, a contraption that ran steam though the soil so that there would always be an ample supply at hand. For years, as you can imagine, I was brainwashed into thinking you could only start seeds in soil that had been pasteurized or otherwise cleaned of pathogens.

The problem with this approach, of course, came to me via "Teaming With Microbes." Nature uses the microorganisms in soil to create soil structure and feed plants. Almost any attempt to kill off the bad guys in the soil, unfortunately, also kills off the good guys. This leaves you, the gardener, as the one who has to replace the functions of these now-absent microbes and they are many (both functions and microbes).

To accomplish this chore, you have to make sure that no pathogens get into your soil and infect you seedlings. This is one reason why good air circulation is advised as it helps keep fungal spores from infecting plants and causing "damp off" (wherein all the seedlings simply fall over). A fungicide, of course, will prevent that, but what of the good microbes? And since microbes feed the plant, where are they going to get food? Now you have to fertilize, and what do you know about feeding a seedling?

Today, of course, unless you sell soil, the practice is to use nonsterile growing media. Instead of ridding the soil of all microbes (as did my father and his), the trick is to get enough microbes and a large enough diversity of them so that pathogens are naturally kept in check, they being only a small subset of the total microbial population. This is best accomplished by either using pure compost or humus, both full of microbial life. Once seeds are started, you can transplant them into last year's soil mix, preferably with a bit of fresh compost added.

In addition to compost, of course, you can add compost tea to seedlings and seed starting soils. Look for it at local nurseries or make your own. This is an extract of microbes contained in compost. And compost contains all the microbes a plant could ever want.

Next, feeding seedlings. So when do you feed seedlings and transplants? Obviously, the answer to this one depends on how good your starting mixture is, that is, how many nutrients it contains as well as the kind of microbiology there is to cycle the nutrients into useable form. However, all seedlings will feed themselves if there are nutrients available, especially if you infected them with mycorrhizal fungi. It shouldn't be necessary to feed seedlings for the first three weeks or so of growth.

After three weeks, almost all seeds have growing roots, which probe down into the soil and absorb nutrients. The trick here is to band some of the key nutrients into the layer where these roots will grow. I like to use a mixture of kelp (which contains all the micronutrients a plant would need) and a bit of soybean meal, which I place about two or three inches below the soil surface in a broad layer that is itself an inch or so deep. I would suggest repeating this trick before transplanting, whether into the ground or into another container.

Next, proper watering makes all the difference when growing seedlings. When I lecture around the country on my books, I point out that one of the reason you water is not to keep the plant alive, but to keep the microbes that feed and protect the plant alive. Plants generally tell you wen they need water. They wilt. Microbial signals are not as easy to discern Technically, you never want a plant to wilt, as the plant expends energy on the wrong things when it does.

If you catch it in time a wilting plant will recover. It takes longer for microbes, however, so don't let the soil dry out. By the same token, over-watering will drown both the plant and the microbes by depriving them of oxygen, so you shouldn't overwater either. Get in the habit of checking your plants' soil every day to make sure they are ok. Feel like sand? It is too dry. You know what too wet feels like. Unsure? Put a paper towel on it. It should draw up just a bit of water.

Finally, make sure your starts are getting the very best light they can. So what if this means you have to take up the best space in the living room or bedroom. A good start will ensure the veery best plants this summer.

Jeff Lowenfels is the co-author of "Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web" and author of "Teaming with Microbes: The Organic Gardener's Guide to Optimizing Plan Nutrition."

Jeff's Alaska garden calendar

Tuberous begonias: Time to start. Get yours out of storage. Buy new ones. Concave side up. Don't get soil in the divot in the middle of the tuber.


Vegetables to start: Tomatoes, peppers, kale and Brussels sprouts



Herbs to start: Thyme, oregano and parsley



Flowers to start: cosmos, snaps, ageratum, seed dahlias, godetia, asters, phlox, celosia, salvia, lupin, malva, pansies and petunias



Nurseries: They are open and you really owe it to yourself to visit a few. It's been a weird, long winter.



Jeff Lowenfels