A Seed-Starters Glossary

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You don’t understand the language used in seed catalogs? You’re not alone! Source: www.barnesandnoble.com, pngimg.com & journalofantiques.com, montage jardinierparesseux.com

Seed and plant catalogs wing your way to your door and pop up on your screen. Garden centers are full of displays of seed packets of all kinds. It’s so exciting! You dive in and try to pick out the very best plants for your use. But the vocabulary found on the back of seed packs and in printed and virtual seed catalogs can be arcane, even confusing. For many beginners, it’s like reading a foreign language! To help you, here are a few terms you may encounter and their definitions.

Acclimatization: A vital action taken just before transplanting seedlings outdoors. It simply means to place the seedlings, still in their pots, outdoors in the shade for 2 or 3 days, then in partial shade for 2 or 3 days, then in full sun for 2 or 3 days. The seedlings are now “hardened off” and ready to transplant to their permanent location.

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Annuals grow quickly, but die after they bloom. They leave seeds to start a new generation. Illustration: Twinkl

Annual: a plant that completes its life cycle, from germinating to seed production, in one single year, then dies. Ex.: cosmos, marigold, sunflower.

Hardy Annual: an annual that tolerates cool soil and even a bit of frost. It is usually sown directly in the garden, early in the spring. Ex.: spinach, sunflower.

Half-Hardy Annual: an annual that tolerates could soil, but not frost. It is usually sown indoors in short-season or cool climates, but directly outdoors in warmer ones, as soon as there is no risk of frost. Ex.: cosmos, lettuce, petunia.

Tender annual: a plant grown as an annual that needs constant warmth and will not take frost. In all but tropical climates, it is generally started indoors and transplanted into the garden when both the soil and air have warmed up and there is no risk of frost. Ex.: basil, begonia, tomato.

Biennial: a plant that completes its life cycle in two years, usually producing a rosette of leaves the first year and flowers and seed the second. It dies after seed production. Ex.: foxglove, parsley.

Perennial: a herbaceous plant (not woody) that lives more than two years and that blooms more than once. It does not die after flowering.

Botanical Name: see Scientific Name.

Bush-type: see Non-Running.

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Leaf suffering from chlorosis. Source: utahpests.usu.edu

Chlorosis: when leaves contain insufficient chlorophyll. They are often pale, yellow, or yellow-white. An iron deficiency, or lack of iron, is a common cause of chlorosis. See Nutrient Deficiency.

Cold Treatment (Stratification, Vernalization): subjecting to cold temperatures seeds that need to go through a cold period before germinating. Usually they are sown in pots of moist soil and placed in a refrigerator for several weeks before exposing them to heat. An alternative is to sow them outdoors in the fall in a cold climate where they will naturally undergo cold temperatures. Many perennials, shrubs, and trees from temperate climates require a cold treatment.

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Seedling with two cotyledons. Source: www.canolacouncil.or

Cotyledon: a seed’s first leaf, usually simple and often very different in appearance from mature leaves. Most seedlings have two cotyledons, but there are seedlings with only one cotyledon, more than 2 cotyledons and without any cotyledon.

Cross-Pollination: The transfer of pollen from the anther of a flower of one plant to the stigma of a flower of another plant of the same species. It is usually carried out by insects, birds or wind.

Cultivar: a plant raised and multiplied by humans, that does not exist in nature. Its name is typically written between single quotes (‘   ‘). The name derives from “cultivated variety.” Ex.: in Cosmos bipinnatus ‘Sonata White’, ‘Sonata White’ is the cultivar name.

Determinate: said of a tomato plant (and a few other plants) in which each branch ends in a cluster of flowers, which therefore limits its upward growth. Determinate tomatoes make fairly small plants and don’t always need staking. They tend to produce all their tomatoes at about the same time.

Indeterminate: said of a tomato plant (and a few other plants) whose flowers appear in the axils of branches and not at the stem tip. Therefore the stem continues to grow in height throughout the growing season. These tomatoes need staking or a large tomato cage. They may produce less fruit at once than a determinate tomato, but usually do so over a long harvest season and often give double or triple the yield of a determinate tomato.

Dioecious: refers to a plant whose male and female flowers are borne on different plants. The asparagus is dioecious.

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Male (left) and female (right) squash flowers. Squash plants are monoecious, thus flowers of both sexes are borne on the same plant. Source: www.missouribotanicalgarden.org

Monoecious: refers to a plant that produces separate male flowers and female flowers on the same plant. Often the female flower is easily recognized because it has a small ovary at its base in the shape of the fruit to come. Squash, melons and cucumbers are monoecious.

Perfect Flower (Bisexual Flower, Hermaphroditic Flower): said of a flower that has both male and female organs, thus both a stigma and stamens. This is the most common situation in nature.

Direct Sowing (Direct Seeding): sowing a plant directly outdoors where it is to grow. Beans, marigolds, and corn are often direct sown.

Do not cover: said of a seed that should not be covered with soil at sowing, usually because it is either very fine or requires light to germinate, or both.

GMO: genetically modified organism. Said of a plant into which humans have inserted genetic material from another plant or even an animal without going through pollination. There is, for example, corn containing the genes of Bt (a bacterium) and varieties of canola and soybean which with inserted genes that make them resistant to herbicides. At the time of writing this, there are no GMO seeds or plants available to home gardeners.

Hardening Off: see Acclimatization.

Heirloom Vegetable (Heirloom Plant): an old variety. Some authorities consider a plant having been introduced more than 50 years ago to be an heirloom variety, others prefer the definition “before the 1940s.” Most heirloom vegetables are produced through open pollination, that is pollination carried out by insects, birds, or wind. Examples.: ‘Brandywine’ tomato, ‘Golden Bantam’ corn, etc.

Hybrid: plant resulting from the crossing of two different breeds, species or genera. F1 hybrids are the most common type of hybrid and are the result of a first-generation cross (F1 means “1st filial generation”). Usually, F1 hybrids are more robust than non-hybrid plants, but more expensive, because they have to be manually pollinated in a greenhouse setting. F2 hybrids, less common on the market, are seeds of F1 hybrids, thus the second generation (2nd filial generation). They are cheaper, as they are generally produced by natural pollination, but tend to give less reliable results than F1 hybrids.

Last Frost Date: see Spring Frost-Free Date

Latin Name: see Scientific Name.

Nutrient Deficiency: results from the lack of a vital mineral in the soil (phosphorus, potash, nitrogen, zinc, boron, iron, etc.). It can have various symptoms include discolored or deformed leaves or slow growth. Treatment with a complete fertilizer (containing all the trace elements, such as a seaweed or fish fertilizer) will usually overcome a deficiency.

Organic: various definitions. Organic seeds are harvested from plants that have not been treated with synthetic (that is to say, chemical) pesticides or fertilizers. Organic pesticides and fertilizers are derived from natural sources, not from chemical synthesis.

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Peat pots. Source: amazon.com

Peat Pot: pot made of pressed peat, coir or other organic materials, usually used for seedlings that will not tolerate transplanting. The peat pot allows roots to grow right through its sides and bottom and can therefore be transplanted into the garden without removing it. The roots of the plant will then grow right through the peat pot into the surrounding soil.

Pelleted Seed, Seed Pellets: seeds covered in a product (usually clay) which facilitates their handling.

Multi-pellets: seed pellets that include several seeds and are used for plants that look best when grown in a clump, such as bedding lobelias.

Pinching: removal of a plant’s terminal bud (bud at the end of the stem). Pinching stimulates branching, giving a more compact and attractive plant, but may delay flowering. It is traditionally done by “pinching” the top growth between the thumb and forefinger, but can also be done using pruning shears or scissors.

Requires Light to Germinate: said of a seed that germinates only in presence of light, be it sunlight or artificial lighting. These seeds should be sown without covering them with soil and the pot should be placed in a brightly lit spot.

Running: said of a squash with long creeping stems that require a lot of space in the garden, like a pumpkin. This is the natural state for squash.

Non-Running (bush type): said of a squash that produces a short stem and a rosette, taking up less space in the garden than a running squash. The zucchini is the best known non-running squash.

Scarification: action of filing, nicking, or cutting a seed before sowing it. It can also involve soaking it for several hours in warm water. The goal of scarification is to penetrate very hard seeds (morning glories, hibiscus, etc.) and thus accelerate their germination.

Scientific Name (Botanical Name, Latin Name): it consists of two words, the first being the genus name (name shared with related plants, much like a human surname) and the second, the specific name, which determines the plant accurately. For example, Solanum tuberosum is the scientific name of the potato and Solanum melongena, of the eggplant. Both share the same genus name, Solanum, because they are closely related, while the specific name serves to make it clear to which type of Solanum the writer or speaker is referring. The scientific name is usually written in italics when possible.

Self-fertile: refers to a plant whose flowers can self-pollinate, that is to say that its own pollen can ensure seed production. Most plants are self-fertile.

Self-sterile: said of a plant which has to be pollinated by another variety in order to produce seeds. Many fruits (apples, pears, plums, cherries, etc.) are self-sterile or partially self-sterile. In their case, it is always best to cultivate at least two cultivars of the same species nearby, as cross-pollination is necessary for them to produce abundant fruits.

Spring Frost-Free Date: the date used in calculating when to start tender plants indoors, referring to the approximate date when you can expect there is no longer any risk of spring frost, usually about 2 to 3 weeks later than the average last frost date. (About one year out of two, there will be frost after the last average last frost date: that’s why it’s an average.) On seed packs and in seed catalogs, you’re often told to start seeds indoors so many weeks (6 weeks, 8 weeks, etc.) before the spring frost-free date. You can ask a local garden club or garden center for the last frost date in your region, then simply count backwards to find the right date for sowing seeds.

Stratification: see Cold Treatment.

Thinning: removing some seedlings or fruits in order to allow room for others to grow better. Usually this is done by cutting the excess plants or fruit stalks the base.

Transplanting: moving a plant from one place to another. In the case of seedlings, this is usually from the pot in which they were sown into a larger pot or into the ground.

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Treated seed is inevitably stained bright colors to avoid any confusion with non-treated seed. Source: http://www.sulphurmills.com

Treated seed: seed has been treated with a fungicide to prevent rot in cold or wet soils. This treatment is not considered acceptable to organic gardeners.

Untreated Seed: seeds that have not been treated with fungicides and therefore acceptable in organic gardening.

Vernalization: see Cold Treatment. It can also mean subjecting growing plants to cold in order to stimulate flowering.20180420A ENG www.barnesandnoble.com, pngimg.com & journalofantiques.com .jpg

Cold Treatment in a Crowded Fridge


20160215AB.jpgMany perennial seeds, shrubs and trees need a long period of moist cold before they will germinate. In fact, I wrote about the subject fairly recently, including a list of seeds that need a cold treatment. See Time to Give Hardy Seeds Their Cold Treatment. But the technique explained how to sow seeds in small pots that are then stored in the refrigerator for up to 3 months… and not everyone has enough space in the family fridge for pots of seedlings. Fortunately, there is a space-saving solution.

Before I explain that, however, it is important to understand simply putting the seed pack as is in the refrigerator will have no effect. To stimulate germination, these seeds need to be exposed to both cold and moisture. However, you can easily give the seeds a cold treatment without either pots or soil and thus save space.

20160215B.pngJust moisten a paper towel and wring it out (you want it to be slightly moist, not soggy). Place the seeds you want to germinate on the paper towel, then fold it in half, pressing the top half down on the seeds to ensure a good contact. Slip the paper towel into a plastic sandwich bag and place the bag in the refrigerator, flat or even upright. It will take much less space than a pot of soil. You can even stack multiple bags on top of each other or place a carton of milk or other objects on top of the bag or bags, so essentially they take up no space in the refrigerator.

Don’t forget to insert a label with the plant’s name and the date you sowed them inside the bag or to write that information on the outside of the bag.

Most seeds will need 2 or 3 months of cold. When this period is over, take them out of their bag and simply sow them in pots of moist soil, reusing their plastic bag as mini-greenhouse until they germinate. Next expose the pot to warm temperatures in a well-lit spot and when the seedlings emerge, remove the plastic bag and grow them on as you would with any other seedling.

There you go! There are more steps involved, but at least you’ll have room for something besides pots of seeds in your refrigerator over the coming months!

Time to Give Hardy Seeds Their Cold Treatment


Many hardy seeds will only germinate if given a cold treatment.

Many seeds require a lengthy period of cold temperatures before they will germinate. This group includes most trees and shrubs from cold and temperate climates, but also many perennials and even a few annuals. This process is called “cold stratification” because originally the seeds were layered (stratified) between layers of moist soil before exposing them to cold, but term “vernalization” is also used. The term “cold treatment” seems to be gaining ground, though, and it really does best explain the process.

The most obvious way of giving seeds a cold treatment is to sow them outside in the fall, but that often leaves them exposed to insects, mammals and inclement weather. It’s far safer to give seeds their cold treatment indoors, where you can keep a closer eye on them… and where nothing can eat them. It’s usually carried out in January or February so the young plants will be ready to plant out come spring.

Giving hardy seeds a cold treatment replicates what happens in the wild. There the seeds fall to the ground in the autumn and remain there all winter, exposed to cold and moisture. Then they germinate in the spring when the weather warms up. And many seeds require this cold-to-warm cycle: without it, they won’t germinate or will do so only very poorly.

The need for cold stratification developed over many millennia as a way of preventing seeds from germinating at the wrong season. Seeds that don’t need cold stratification often start to germinate when the weather is unusually warm in the late fall or when there is a January thaw, then the fragile seedlings are killed when cold weather returns. Those that have an obligatory need for stratification, however, won’t react to unseasonal conditions. They essentially have an internal clock telling them: “Look, it’s too early to germinate! Wait a few months more before you start to sprout.” In general, the longer the winters are in the plant’s native land, the longer the cold treatment it will require.

Cold and Moist

Beginners often don’t understand a vital detail: it’s not cold alone that stimulates germination, but cold combined with moisture. So you can’t just place the seed packets in a fridge for a few months and expect the seeds to germinate well, you need to put them into contact with moist soil first.

The other common error is freezing the seeds. Although most of these seeds will tolerate freezing temperatures, freezing the seeds is not necessary and actually slows the process down. For best results, give temperatures just above freezing, between 34°F and 41°F (1°C and 5°C). And as luck would have it, the temperature of a typical domestic refrigerator typical falls right in that range: about 35°F to 40°F (1.6°C to 4.4°C).


Sow the sees and put them in the fridge.

Traditionally, you sow the seeds that require a cold treatment in pot or tray, seal it inside a transparent plastic bag and place the container in the refrigerator. Just how long the cold treatment has to last depends on the species, from as little as 1 or 2 weeks to 4 months or more. Ideally you’d check the seed packet label for information. In case of doubt (for example, if you harvested seed yourself and have no idea of its needs), try three months. All these seeds require a minimum number of weeks in the cold, but there is no maximum. So no harm comes from prolonging the cold treatment beyond the minimum.

At the end of the cold treatment, remove the containers from the fridge and place them in a warm bright spot (about 21 to 24˚C is ideal for most seeds) to stimulate germination. Many of these seeds are fairly slow to germinate, so don’t be surprised if they take 3 or 4 weeks, sometimes even longer.


After their cold treatment, the seeds will start to germinate.

From this stage on, simply treat the seedlings like any other. After germination, remove the plastic bag. Start watering whenever the soil starts to dry out. Fertilize when the plants have about four to five true leaves, etc. Finally, when the weather outdoors warms up enough, start acclimating the seedlings to outdoor conditions (place them in the shade for two or three days, then in partial shade for two or three days, then in the sun for two or three days). Once they’re well acclimated, transplant them either to a nursery (plants, such as trees, shrubs and slow-growing perennials, that will take more than a year to be presentable) or directly to their final location (annuals and fast-growing perennials).

If You Lack Fridge Space


You can also sow the seeds in packs of moist vermiculite.

If you lack space in your fridge, you can try a different method of cold stratification. Simply mix the seed in a few spoonfuls of moist vermiculite. Seal the vermiculite in a small plastic bag and put it in the fridge (this takes much less space and you can even pile your bags of seeds one on top of the other). When their cold period is up, simply lay the seed bags somewhere warm and fairly bright. As soon as you see little sprouts start to appear, very carefully pot up each seedling in its own little pot and water. Then proceed from there as above, growing them on and eventually planting them out.

Double Cold Stratification

For some seeds, a single cold treatment is not enough. It takes two! These seeds are very slow to germinate in the wild, often taking 2 or 3 years before they show any sign of life. However, you can get them germinate the very first year treating them to a double cold stratification. Here’s how:

Give the seeds 2 to 3 months in the fridge, expose them to warmth for 2 months, then put them back in the refrigerator for 2-3 months. This time, when you bring them out of the fridge, they should start to germinate… and if they don’t? Put them back in the fridge and try again. It once took me 4 alternating cold and warm treatments to get some stubborn trillium seeds to sprout!

Species Requiring a Cold Treatment

Here is a partial list of the seeds that normally require a cold treatment to germinate. However, there are many others. Always read the instructions on the back of the seed packet to see if the seeds you bought need this kind of care… or check out their needs on the Internet.

If in doubt, find out where the plant grows in the wild. If comes from a cold region and its seeds ripen in the fall, there is a very good chance that its seeds will require a cold treatment to germinate.

  1. Althaea (marshmallow)
  2. Astrantia (masterwort)
  3. Baptisia (false indigo)
  4. Buddleia (butterfly bush)
  5. Caltha (marsh marigold)
  6. Caryopteris (bluebeard)
  7. Cercis canadensis (redbud)
  8. Chelone (turtlehead)
  9. Cimicifuga (bugbane)
  10. Clematis (clematis)
  11. Cornus (dogwood)
  12. Corydalis (fumitory)
  13. Delphinium (delphinium)
  14. Dicentra spectabilis, now Lamprocapnos spectabilis (bleeding heart)
  15. Dictamnus (gas plant)
  16. Dodecatheon (shooting star)
  17. Echinacea (purple coneflower)
  18. Eremurus (foxtail lily)
  19. Filipendula (meadowsweet)
  20. Eryngium (sea holly)
  21. Eupatorium (Joe Pye weed)
  22. Forsythia (forsythia)
  23. Fragaria (strawberry)
  24. Fuchsia (fuchsia)
  25. Gentiana (gentian)
  26. Geranium (cranesbill)
  27. Goniolimon (German statice)
  28. Helianthemum (rock rose)
  29. Helianthus (perennial sunflower)
  30. Heliopsis (false sunflower)
  31. Helleborus (Christmas rose)
  32. Hemerocallis (daylily)
  33. Heuchera (coral bells)
  34. Hibiscus moscheutos (perennial hibiscus)
  35. Hypericum (St. John’s wort)
  36. Iberis (perennial candytuft)
  37. Ilex* (holly)
  38. Incarvillea (hardy gloxinia)
  39. Kirengeshoma (waxbells)
  40. Knautia (knautia)
  41. Lathyrus (perennial sweet pea)
  42. Lavandula (lavender)
  43. Leontopodium (edelweiss)
  44. Iris (iris, many species)
  45. Lobelia (hardy lobelia)
  46. Lonicera (honeysuckle)
  47. Macleaya (plume poppy)
  48. Magnolia* (magnolia)
  49. Malus (apple, crabapple)
  50. Mazus (creeping mazus)
  51. Mertensia (virginia bluebells)
  52. Myrrhis odorata (sweet cicely)
  53. Nepeta (catmint)
  54. Oenothera (evening Primrose)
  55. Muscari (grape hyacinth)
  56. Opuntia* (beavertail cactus)
  57. Paeonia* (pivoine)
  58. Penstemon (beard-tongue)
  59. Persicaria (fleeceflower)
  60. Phlox (phlox)
  61. Physalis (chinese lantern)
  62. Persicaria orientalis, syn. Polygonum orientale (kiss-me-over-the-garden-gate)
  63. Picea (spruce)
  64. Platycodon (balloon flower)
  65. Primula (primrose)
  66. Pulsatilla (pasque-flower)
  67. Quercus (red and black oaks)
  68. Ranunculus (buttercup)
  69. Ratibida (prairie coneflower)
  70. Rosa (rose)
  71. Rudbeckia (black-eyed Susan)
  72. Sambucus (elderberry)
  73. Sanguinaria (bloodroot)
  74. Sanguisorba (burnet)
  75. Saponaria (soapwort)
  76. Saxifraga (saxifrage)
  77. Scabiosa (pincushion flower)
  78. Sedum (stonecrop)
  79. Sempervivum (houseleek)
  80. Sidalcea (prairie mallow)
  81. Silphium (cup plant, compass plant)
  82. Staphylea* (bladdernut)
  83. Stokesia (Stokes’ aster)
  84. Syringa (lilac)
  85. Thalictrum (meadow-rue)
  86. Tiarella (foamflower)
  87. Tricyrtis (toad-lily)
  88. Trillium* (trillium)
  89. Trollius (globeflower)
  90. Tsuga (hemlock)
  91. Vernonia (ironweed)
  92. Veronica (speedwell)
  93. Viola (violets)
  94. Vitis (grape, some species)

*Some species in this genus require a double cold stratification.