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Three Timely Tomato Topics: Feeding Seedlings, Adding Calcium & What to do with Horse Manure


Q. I started my own tomato plants this year; they're indoors under lights, and so far so good. I used 'Natural Beginnings Soilless Mix' as the growing medium, and the package says to start feeding when the seedlings are four weeks old. I would like to use fish emulsion (because that's what I have on hand). Can you tell me what strength to use?

---Susan in Berwyn, PA

A. I also use Natural Beginnings; it's a very nice seed starting mix—a combination of two natural materials that provide the drainage young plants require: coir (a peat moss substitute made from coconut husks) and perlite (a volcanic glass), plus a touch of two natural fertilizers: worm castings and mealworm guano (or in other words, two different kinds of worm poop).

Those wonderful worm excrements give baby plants a nice gentle feeding—the same kind they'd receive in a natural setting where leaf litter encourages earthworms to live nearby and poop out plant food. And four weeks sounds just about right to start giving your plants a little more food—but I would never use something as odoriferous as fish emulsion indoors. (At least not again; I can still hear my wife yelling at me 25 years ago!) Always consider the smell factor with indoor plant food!

I've tried many different fertilizers on baby plants over the years and have settled on worm castings as the best. They're easy to find at retail and mail order, have no odor and give the plants a gentle, natural feeding. I just top off the soil with about an inch of castings when I move my starts up into bigger pots (when they're four to five weeks old).

Or you could water the plants with some worm poop tea. Fill an old sock with worm castings, hang it in a gallon of water for 24 hours and use the dark colored brew right away. (Then empty the sock contents into your compost pile or worm bin; or dump it out near garden plants outside; there's still good stuff in there!)

And save the fish emulsion for outdoor use. (Although I greatly prefer fish and seaweed mixes to fish emulsion alone.)

Q. I've been reading your book, "The You Bet Your Garden Guide to Growing Great Tomatoes", and holy cow - the mistakes I've been making! One thing I'm going to improve upon for sure is adding calcium to prevent blossom end rot. But you recommend using eggshells for this and I'm not sure I can collect enough shells in time for planting. If I use an organic tomato food that specifies it contains added calcium, will it be as beneficial? Or is the power of eggshells hard to duplicate? Thanks!

---Erika in Wellington, Colorado (about 75 miles north of Denver and 35 miles south of Cheyenne. Dry, extremely sunny, very windy and late to start--I would guess that my USDA gardening zone is barely a 5)

A. Well, first—thanks for buying my tomato book, Erica; that's another 47 and a half cents in the retirement fund! Ka-ching! Now, the short answer is that natural fertilizers that specify they contain added calcium should be fine—preventing the heartbreak of blossom end rot, improving the flavor of your love apples and doing all the other good things that calcium does for tomatoes.

I started specifically recommending adding crushed eggshells to the hole at planting time simply because I found it was a great way to use my eggshells. We seem to eat just enough eggs over the course of a year to provide a dozen crushed shells for each of my tomato plants—and cucumbers since I learned that adequate soil calcium keeps them nice and crispy—and I have found eggshells to be stubbornly recalcitrant in compost piles.

Q. My daughter recently started taking riding lessons, and I now find myself with access to horse manure. Is this a good thing to add to my veggie or flower gardens, and if so, how? Is there a way to liquefy it? Would a manure tea feeding help my peppers, tomatoes, cucumbers and summer squash? Thanks,

---Gene in Ambler PA

A. If I had a dollar for every time somebody has come up to me at a show and said "my grandparents only used horse manure and had the best tomatoes around", I'd be a lot closer to that retirement fund. But I can't recall anyone ever coming up to me and saying that they personally layered their garden in equine excrement and had a good experience.

First, horse manure must be thoroughly composted before use. Horses have very inefficient digestive systems that pass lots of seeds through without harm to the seeds; so anyone foolish enough to use fresh horse manure in their plots will spend the summer battling ferocious weeds. And the weeds will win. And fresh manure in any form—solid or liquid—is so 'hot' with Nitrogen it can injure ('burn') plants.

Now, the stable sweepings that horse owners have access to are a combination of the two things the horse decided to get rid of (solid and liquid) and the bedding used to keep the stalls clean and less slippery. And piling up this combination of Nitrogen rich waste and dry brown bedding for several months to a year (depending on factors like climate, air temperature, and the size of the pile) produces a material that, when finished, is dry, crumbly and virtually odorless. But it is not "compost". It is composted manure and still overly rich in Nitrogen—the nutrient that grows big plants but that can inhibit fruiting and flowering.

That makes completely composted horse manure a perfect fertilizer for plants that like a lot of Nitrogen—like sweet corn and lawn grasses, but less than ideal for fruiting crops like tomatoes and peppers.

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