Only January, Yet Already Time to Sow Seeds?



20180103 ENG, &

It’s only January! Surely it’s too soon to sow seeds? Source:, & mzayat. com

The new year has barely begun, yet now and over the coming month it’s already time to start certain seeds indoors.

This is a very select group of especially slow-to-mature plants. January is far too early for most seeds (think March or April instead), but you need about four to five months of indoor culture to bring the following plants to the right state of growth for outdoor planting.

  1. Agastache (Agastache foeniculum)
  2. Datura (Datura metel)
  3. Fairy Snapdragon (Chaenorrhinum origanifolium, syn. glaerosum)
  4. Lisianthus (Eustoma grandiflora)
  5. Spike dracaena or cabbage palm (Cordyline australis, syn. indivisa)
  6. Tritome (Kniphofia )
  7. Tuberous Begonia (Begonia × tuberhybrida)

No Easy Feat!


Artificial light is almost essential for seeds started in January. Source: laidbackgardener. blog

Starting seed in January in the Northern Hemisphere is not simple. The days are short, the sun is weak and, in many areas, the weather is gray more often than sunny, meaning light is seriously lacking. Also, temperatures in front of the average windowsill are cool, yet almost all seeds need warmth—and fairly even temperatures—to germinate well. As a result, you pretty much have to start these under artificial lights, such as fluorescent or LED plant lights, and in the warmest part of your home.


Germinate the seedlings under glass, possibly over a heating pad, as above. Source:

Always start winter-sown seeds “under glass” (under some sort of transparent covering) to maintain high humidity and stable temperatures and in a room that is at least moderately warm (72 to 75˚ F/21 to 24˚ C) or place the seed containers on a heating pad (one specifically designed for plants). Use a timer to set the day length of your lamp at 14 hours to simulate the long days of summer and place the containers of freshly sown seeds about 6 to 12 inches (15 to 30 cm) below the lamp. Now, wait patiently for germination to occur. (One reason that certain seeds need early sowing is that they are slow to germinate.)

Seeds That Require a Cold Treatment


Many tree, shrub and perennial seeds need a cold treatment before they will germinate. Source: laidbackgardener. blog

January (or December or February) is also a good time to start seeds that need a cold treatment (cold stratification) to germinate well. This group includes most trees and shrubs from cold and temperate climates, but also many perennials and even a few annuals.

These seeds will not germinate until they have received a given number of days of cool, moist conditions, from as little as one or two weeks to four months or more, information you would (hopefully) find on the seed pack.

The number of weeks given is the minimum requirement for that species, but there is no maximum. So, if you keep seeds that need, say, a two-week treatment in the cold for two months, that’s not a problem. That’s nice to know, because the information on the minimum cold treatment for seed X is not always available, especially for seed you harvested yourself. If you don’t know, I suggest giving seeds of perennials a six to eight-week cold treatment: that’s usually enough. For trees and shrubs, I’d recommend three months.

Simply sow these seeds in a container as you would any other, then seal them inside a clear plastic bag and pop them into the refrigerator or cold room for at least the minimum number of weeks. Afterwards, move them to a warm, well-lit spot, on a windowsill or under lights, for germination to start.

100 Seeds That Need a Cold Treatment

Here are 100 plants that germinate best with a cold treatment (there are thousands of others!). Check the seed envelope or the seed supplier’s web site for more information.

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

Good growing!20180103 ENG, &

Ground Cherries: Yours to Discover!


Ground cherries (Physalis pruinosa)

The ground cherry (Physalis pruinosa, sometimes identified as P. pubescens), also called husk tomato, husk cherry or strawberry tomato, is still a novelty to many gardeners. Yet, surprisingly, it has been grown for generations and is quite possibly the easiest vegetable to grow in the entire nightshade family (Solanaceae), a group that includes such popular plants as tomatoes, peppers, potatoes and eggplants.

Locally I mostly see ground cherries in restaurants where it is used as a garnish, but you can use in multiple ways in the kitchen, from preserves and salsas to coulis and salads… or simply pop one in your mouth whenever you want a tasty treat.

The fruit may look much like a golden cherry tomato, but is much sweeter: some people say it tastes like a cross between a tomato and a pineapple. I’ve learned from experience that you can’t send children out to harvest ground cherries: they’ll eat far more than they’ll bring back to the kitchen.

Of course, as you’ve probably guessed by now, this plant is in no way related to true cherries (Prunus spp.). The latter grow on woody trees or shrubs and belong to the Rose family, while the ground cherry is a fast-growing annual related to the tomato. Also, the fact its fruits comes gift-wrapped in a papery husk ought to be a sure giveaway.

Both Attractive and Tasty


Ground cherry (Physalis pruinosa)

The ground cherry makes an attractive, shrublike small plant from 1 to 3 feet (60-90 cm) tall with somewhat arching branches. The leaves are elliptic or heart-shaped, toothed along the edges. The bell-shaped flowers are yellow marked with purplish brown spots: attractive enough, but often somewhat hidden from view. After the corolla drops off, the calyx expands to cover the fruit (conveniently protecting it from predators), resulting in a not-unattractive lantern-shaped husk. Foodscapers take note: the ground cherry is certainly attractive enough to merit a spot in the flowerbed, not just the vegetable garden.

Inside the husk is a fruit that will turn yellow or orange at maturity. You’ll know the fruit is ripe when the green husk turns beige and drops off the plant with the fruit inside. The name “ground cherry” comes from the fact that you harvest the fallen fruit from the ground. Some people spread a cloth under the plants to make harvesting the fruits easier.

‘Aunt Molly’s’, ‘Cossack Pineapple’ and ‘Golden Husk’ are among the more common varieties available, but most ground cherry seeds sold have no cultivar name.

Start Indoors

Although this plant is native to Eastern North America as far north as Wisconsin, suggesting a certain tolerance of cool conditions, you’ll find you’ll get much better results if you start it indoors like you would a tomato, about 8 to 9 weeks before the last expected frost. Sow the seeds about ¼ inch (0.6 cm) deep in a tray of potting soil. Thin the plants when the first two true leaves form. It’s quite a fast grower, so move each plant fairly soon into its own 4 inch (10 cm pot).

Transplant outdoors when there is no longer any risk of frost and the temperature has warmed, spacing plants about 18 inches (45 cm) apart. It prefers full sun and rich, well-drained soil, but will tolerate poor soil. Water as needed, as prolonged drought will reduce the quantity and quality of harvested fruit.


Ground cherry flower

The flowers are self-pollinating, like tomatoes, although also like tomatoes, giving the flower a bit of a shake every now and then can help ensure better pollination (read Pollinate Your Tomatoes With a Toothbrush for more information). Bumblebees are experts on “buzz pollinating” the flowers, shaking the pollen loose to make sure the stigma gets its fair share.

You can easily extract and dry seeds for next year’s garden. In fact, the seed can remain viable for up to 10 years.

The earth cherry has few enemies… or at least, they rarely do any serious damage. Be sure, however, to pick up any fallen fruit, as it does tend to self-sow and become weedy. (In some areas, self-sown plants may not have a long enough growing season to produce fruits).


One warning: like almost all Solanaceae (tomatoes, potatoes, eggplants, etc.), the plant’s leaves, stems, flowers and even husk are toxic. Just eat the fruits, nothing else. This also applies to all Physalis species.

Three Close Relatives

The genus Physalis contains some 75 to 90 species, most native to the New World, especially Mexico, and confusion reigns when it comes to their proper identification. I won’t be surprised if future studies result in a lot of changes to their botanical names!

Cape gooseberry (P. peruviana)


Cape gooseberry (Physalis peruviana). Source: mr, Wikimedia Commons

Think of this plant as a larger form of ground cherry, with which it is often confused. The plants are taller: usually over 3 feet (90 cm) and sometimes as tall as 6 feet (180 cm), and the fruit is larger as well, although still no bigger than the average cherry tomato. Otherwise they are very similar, with round golden fruit inside a beige husk that falls off the plant at maturity. It’s most popular in warmer climates with a long growing season where it does exceptionally well. In colder climates, it can be slow to mature and is not that tolerant of cool nights. Although it is generally treated as an annual, Cape gooseberry is actually a perennial and will overwinter in regions with mild enough winters (zones 9 and above).


Cape gooseberry (Physalis peruviana)

As for its name, Cape gooseberry, no, it’s not native to Cape Town, but rather to South America. It picked up its moniker because it has been so widely grown in South Africa for such a long time; as early as 1807.

Why it came to be called gooseberry though (a name normally associated with the woody shrub Ribes spp.) is anybody’s guess. You might also know it under the names goldenberry, Pichu berry or Inca berry, the latter two due to its Peruvian origins.

Tomatillo (P. ixocarpa and P. philadelphica)


Tomatillo (Physalis ixocarpa): these particular fruits are a bit overripe!

Two different but very similar species bear the name tomatillo. P. ixocarpa produces pale yellow fruit at maturity; P. philadelphica, purple fruits. Since they are usually harvested when still green (mature fruits tend to be insipid in flavor and overly seedy), you’ll probably never know which one you’re growing.


Tomatillo fruits could be mistaken for small green tomatoes. Source: Diógenes el Filósofo, Wikimedia Commons

Both produce much larger fruit than the ground cherry: up to 2 inches (5 cm) in diameter, so they’re size of a small tomato. This is also the origin of the name, as tomatillo is Spanish for little tomato. The fruit completely fills its husk at maturity to the point where it bursts open and it’s at this moment, when the capsule turns beige, but the fruit is still green, that it is best harvested.

Tomatillo is a staple in Mexican cuisine, widely used to make salsa verde. The fruits are easily told from green tomatoes by their sticky texture.

The tomatillo is a large plant about 3 to 4 feet (90 to 120 cm) high and just as wide. Its weak stems sometimes need support (a tomato cage, for example). It prefers long hot summers and can be difficult to grow in northern regions unless grown under glass.

Also, it’s important to grow at least two plants, because unlike the other Physalis species described here, the tomatillo requires cross-pollination. In other words, a bee or other pollinator must bring pollen from the flower of one plant to the flower of another plant of the same species to ensure fertilization and thus the fruit formation.

Chinese Lantern (P. alkekengi)


Chinese lantern (Physalis alkekengi)

This species is mostly grown as an ornamental for its bright orange lantern-shaped husk that dries beautifully and is used in floral arrangements. Unlike the other commonly grown Physalis species, all of which have yellow flowers with fairly conspicuous purple brown spots, its cream-colored flowers are small and rather discreet if not completely hidden by the foliage. Also, it’s a hardy perennial (to zone 3) reaching from 16 to 24 inches (40 to 60 cm) in height.

Despite the popular belief that the fruits of Chinese lantern are poisonous, they are in fact perfectly edible and can be used just like ground cherries.

This is a very invasive plant because of its wandering rhizomes: plant it somewhere its aggressive nature won’t be a problem. Slugs often damage the leaves at the beginning of the season, but this rarely effects the production of its main attribute: its brilliantly colored husks.

There you go: a few details about a little-known vegetable and a few of its relatives. Maybe the ground cherry is something you’ll want to try growing this summer!