Sowing Seeds

How to Read a Seed Packet

Most seed companies offer good information right on the outside of their seed packets (or inside). Learn to read and understand the specific needs of whatever you’re planting BEFORE you get out into the garden. I recommend looking at your seed packets well before the suggested planting time in your area to familiarize yourself with the seed’s requirements. You can make labels in the winter and do some garden design then too.

oppen seed packet with seeds pouring out onto soil
Photo: congerdesign on Pixnio.

If you have saved any seeds from the last growing season, they are probably good. Most seeds are viable for up to 3 years. Onions, parsley, lettuces, larkspur and delphinium do not always carry over so they are best purchased fresh each year.

Once Spring arrives, remember: DON’T PLANT THE WHOLE PACKET! There may be anywhere from several hundred to a thousand seeds in each packet! You do NOT NEED 50 tomato plants!

You can share a packet with a friend or grow extra plants to donate to the Food Bank or the Plant a Row for the Hungry project, from GardenComm.

Most garden sites will suggest that if you are starting seeds indoors, you should count backwards from your last frost date to plan when your new seedlings can go outside into the garden or container. Johnny’s Select Seeds has a great planting chart. Just type in your last frost date.

Many other seed companies have similar charts.

Here is what you will be most likely to encounter on a seed packet:

woodland garden
Alaska Botanical Garden, Lower Perennial Beds. Photo by Patrick Ryan

Location: Sun or Shade

Most plants require 6 hours of sunlight daily. If starting seeds indoors, you will need additional light. A sunny windowsill is usually not sufficient to grow strong, healthy seedlings. Outdoors you will need a sunny spot for most plants, generally 6 hours per day.

Planting Depth:

A general rule of thumb is to plant the seeds twice as deep as their size. Cover if required and press down gently for good seed-to-soil contact. The proper information will be on the seed packet.

Note: some seeds require light to germinate. “Some, but not all, popular seeds which prefer light for germination are: Achillea, Alyssum, Antirrhinum, Begonia, Calceolaria, Coleus, Exacum, Ficus, Gaillardia, Gerbera, Gloxinia, Helichrysiim, Kalanchoe, Nicotiana, Petunia, most Primula, Saintpauliu and Streptocarpus.” (Source of article  Growing From Seed – Spring 1989 Vol. 3 Number 2 © The Seed Raising Journal from Thompson & Morgan).

See also The New Seed Savers Handbook by Nancy Bubel for some great information on starting your own seeds.

Homemade seed spacer made of plywood and screws
Homemade seed spacer (6 x 6). Photo by Patrick Ryan

Seed Spacing:

Try to sow small seeds thinly to give the small plants room to grow until they are strong enough to transplant to larger containers or into the garden. Generally, a one-inch spacing seems to work for the many greens that can be grown. Johnny’s Select Seed Company has some great information, geared at market growers. Here’s an example from their Grower’s Library on sowing lettuce seeds:

“Baby leaf lettuce: Sow in a 2–4″ wide band, seeds roughly ½” apart, about 60 seeds/ft. Cover very lightly, about ?”, and firm gently.” They are talking about direct sowing in the garden. In a container, sow the whole thing thinly and harvest baby leaves as they mature as a way to thin the plants. Most greens can be harvested by the “cut-and-come-again” method. Renee Shepherd suggests: “To harvest by the “Cut and Come Again”, method, cut with scissors when lettuces reach about 4-5 inches tall to about 2” above the soil line. Water well and fertilize lightly to enjoy several additional cuttings.” You can also remove outer leaves from several plants for a quick salad.

Renee’s Garden website has some great information on this technique.

Square Foot Gardening is another source for proper spacing.

Pre-sprouting seeds
Pre-sprouting seeds. Photo by Patrick Ryan

Number of Days to Germination:

This is an approximate number. Seeds generally need to be kept moist while they are germinating, or “waking up”. If nothing green comes up after a week or so beyond the expected germination date, you may want to replant your seeds. Ed Hume suggests some possibilities for poor germination: “Seeding too deeply, planting in cold soil, extremes of watering, improper soil preparation, birds or squirrels and poor seed are the most common causes for seeds failing to germinate.” Buy fresh seeds or if you have saved them from, last year, you may want to test ten seeds rolled up in a moist paper towel. Place seeds in a small plastic bag and keep in a warm place. Check after a few days. If five or fewer seeds sprout, the germination rate is poor. If all ten sprout, that’s 100%, and you can plant those seeds and the ones in the packet.

Number of Days to Harvest:

This is an approximate number to help in your harvest planning. Weather and watering can affect the time suggested.

Astilboides tabularis, Shieldleaf Rodgersia. Alaska Botanical Garden.

Height of Plant:

An approximate number for planning the height of a mature plant. Tall plants go in the back of the garden.

Children planting seeds in a raised planting bed
Bed preparation for direct seedling outdoors at an elementary school. Photo by Patrick Ryan

Start Indoors or Plant Directly to Garden:

Many seeds can be planted indoors before the last frost date in order to have small plants ready to transplant outdoors after “hardening off”.  Plants need to acclimate to outdoor life with the sun, wind and cooler weather. The benefit of starting your own seeds is mainly because you can choose varieties not available at your local garden centers. And it’s fun!

Outdoors, follow packet directions of spacing, sun, etc. Keep seeds moist while germinating. Sow thinly to save time, money, seed and plants by NOT having to thin them. Carrots are the classic example. Gardeners tend to plant too many seeds and then they must be thinned. They do not transplant well.

Seeds sprouting under artificial lighting
Start seeds early in the North. See Johnny Seeds note in the first paragraph above. Photo by Patrick Ryan

Patrick Ryan is an Alaska Master Gardener and the Education Specialist for the Alaska Botanical Garden. A retired elementary school teacher, Patrick is a member of the Anchorage Community Forest Council and sits on the board for Alaska Agriculture in the Classroom.

1 comment on “How to Read a Seed Packet

  1. Wonderful information. Thank you Patrick.

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