Plant heirloom seeds indoors to get a jump-start on spring

Use small containers such as butter tubs and a sterile seed-starting mix

Scripps Howard News ServiceJanuary 11, 2013 

SH12L199GARDENER Dec. 24, 2012 -- Mature nursery plants are expensive, and not many of the more unusual heirloom varieties come ready to transplant. (SHNS photo courtesy Jordan Crossingham)


Winter is the perfect time to think about next spring’s garden. I have a fascination with heirlooms, which are plant varieties generally over 50 years old and typically passed down through generations. My plans always include plenty of these.

I’ve been starting heirloom seed varieties for years, and I still get a thrill when something so tiny and dry – and with such an interesting history – actually grows into a vibrant, living plant.

There are practical reasons for starting from seed, too. Mature nursery plants are expensive, and not many unusual heirloom varieties come ready to transplant. So starting heirloom plants from seed is often the only way to save these varieties for future generations.

There are plenty of catalogs and websites for folks who grow, sell and share these old-fashioned favorites. The Seed Savers Exchange of Iowa,; Virginia’s Southern Exposure Seed Exchange,; and Native Seeds/SEARCH of Arizona,, are good places to begin your search.

Timing is everything when you’re starting seeds indoors. If you start too soon, the plants outgrow their containers and end up needing more light then a typical indoor home can provide. Start too late, and you’ll have small seedlings that have to be pampered to survive.

The key is the last frost date in your area. Plants set out after that should be safe. In the Triangle, that date usually falls in mid- to late April, though frost can occur even into May.

Find the number of days the seed takes to germinate and grow enough to set out; retail seed packets include this information on the label. Then calculate planting time.

For example, the 1938 AAS winner heirloom summer squash Early Prolific, available from Baker Creek Heirloom seeds,, takes 45 days. If your last frost date is April 25, start the seeds on or around March 12.

Start seeds in most any well-drained small container. Butter tubs, plastic bakery boxes, even pizza boxes are fine. Use a sterile seed-starting mix rather than garden soil. The latter is full of disease organisms and too dense to let young roots develop properly. Moisten the soil-less mix with water to the consistency of fresh brown sugar. Fill each pot to 1/4 inch from the top.

Heirloom seeds may not sprout as well as hybridized seeds, so plant three or four and thin out the weakest later. Cover lightly with additional soil-less mix. Refer to the seed packet for proper sowing depth. The top of the refrigerator supplies important bottom heat for good germination, but a commercial heating mat gives a more consistent temperature.

The instant the seed sprouts, sufficient light is critical. Ordinary fluorescent shop lights work fine when hanging an inch or two above the leaves. You could use one warm-daylight and one cool-daylight tube to provide the full light spectrum, but standard 40-watt tube bulbs work just fine. Set a timer to give the plants 16 to18 hours of light. As the plants grow, raise the lights to keep them about an inch or two above the leaves.

Wait until after the first true set of leaves has developed before feeding with diluted amounts of soluble fertilizer in warm water (three-quarters to one-quarter strength or less), gently pouring at the side of the pot to leave the tender young plants undisturbed. Seedlings are too delicate to set directly into the spring sunshine, so harden them off over two weeks, starting with four hours of sun and adding a half-hour every other day until they’re getting a full eight hours.

Give them the right conditions and they do the rest. With a little warmth, the right moisture and light and a bit of patience, you’ll raise a crop of healthy, garden-ready heirlooms that can’t wait to start growing and pass on their legacy.

Joe Lamp’l, host of “Growing a Greener World” on PBS, is a Master Gardener and author. He blogs at

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