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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Rosa, Planting time, Planting

When should I plant bare root roses?


The Seattle Rose Society suggests planting in March. The roses should be stored in a cool dark place if they cannot be planted right away.

Other recommendations include soaking the roots before planting (8-12 hours), and trimming off damaged or diseased roots. Try to maintain 3-5 canes per plant, and prune back to 3-5 buds per cane.

Dig a hole wide and deep enough to accommodate the roots. Make a cone-shaped mound of soil in the center of the hole to support the plant. Fill the hole 2/3 full of soil and add water to make a slurry--this gets between the roots. Do not tamp the soil. When the water drains, add more soil and repeat the water fill process until you reach the original soil surface (ground level).

Date 2018-04-21
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Plant Answer Line Question

Keywords: Planting time, Paeonia

I was given a tree peony in a container. It even has a couple of buds.

Can I plant it in the ground in spring, or must I wait until fall? How should I prepare the soil for planting?


Expert opinions vary on the importance of waiting until fall to plant tree peonies, or Paeonia suffruticosa. The Sunset Western Garden Book (2007) says "All peonies are best set out in fall", while The Gardener's Guide to Growing Peonies suggests that if peonies are planted in spring, the gardener must be very careful to water them well in dry weather that first summer. Of course, watering will still be an issue if your gift remains in the pot all summer! Also, this same source says in an excerpt:

Tree peonies usually become available in the early spring and...have small flowers. While it is very tempting to allow the plants to flower, this can considerably weaken a young tree peony. The buds are, therefore, best removed...and the shoot pruned to leave three or four leaves... Tree peonies are normally sold...in pots...with a peat-based compost. This is a suitable medium for transport, but the plants can deteriorate if they are not planted out fairly quickly into normal soil. ... In the autumn, it can be dug up...and planted correctly in its permanent home.

I don't know about you, but I wouldn't be willing to nip off those little buds! The "heeling in" practice, which involves planting the peony temporarily, might work though. Organic Gardening magazine has an article from which you can read an excerpt:

To heel them in, choose a sheltered, shady site and dig a V-shaped trench. Make the trench wide and deep enough to accommodate the plants' roots and long enough to prevent crowding. Place the plants in the trench at an angle, making sure the roots are below ground level. Refill the trench with soil (don't pack it down) and water the plants thoroughly. Check the soil moisture occasionally and water as needed. "You can leave plants heeled in for months, but I would suggest holding them that way only for a few weeks," says Amy Grotta, extension faculty in forestry education at Washington State University. "You don't want them to break dormancy before planting." Plants that come out of dormancy early are susceptible to frost damage, so plant as soon as possible to prevent harming your new purchases.

Directions for preparing the soil are very consistent in different literature: your tree peony will need a sunny site with rich soil, and "Tree peonies benefit from the application of a heavy layer of compost--particularly if they are grown in sandy soil" (says Martin Page in The Gardener's Guide to Growing Peonies). At least several days before planting, you should dig a hole at least one foot in diameter, and up to 3 feet in diameter, and amend the soil as needed in that planting hole. Unlike herbaceous peonies, tree peonies are planted 6 inches deep (that is, with the graft union 6 inches deep).

Date 2017-06-09
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Plant Answer Line Question

Keywords: lunar gardening, Planting time

I've heard that planting the garden according to phases of the moon has some benefits, but I've always wondered if there's any truth to this. Is there any research out there on this topic?


Thank you for your interesting question. I found comments from the point of view of an astronomer on Cornell University's "Curious About Astronomy?" webpage, excerpted here:

"There are two main ideas behind moon gardening practices. First, lunar gardeners believe the moon's gravitational pull affects the flow of moisture in the soil. Just as the moon has a noticeable effect on the oceans in the tides, the moon may have a subtler effect on smaller bodies of water and thus change the levels of water in the soil. For example, to take advantage of the lunar cycle, a gardener would avoid turning over the soil in his or her garden when there is the most moisture in it (and thus when the soil was hardest to turn over) which lunar gardeners propose is during the new and full moons. Another, less direct, proposed connection between the moon and gardening is that moonlight is thought to have an effect on seed germination because exposure to light can enhance germination.

I could not find any extensive scientific studies conducted to test the proposed benefits of lunar gardening. There was a study done by the Agricultural Research Service in Iowa where they found a link between weed germination and exposure to light. They determined that tilling the soil (i.e. bringing weeds to the surface) was best done at night by a new moon (when there was as little light as possible). Tilling in the dark led to less weed seed germination and thus to fewer weeds in the garden.

More studies definitely need to be done to test the possible connections between the Moon and gardening before I am convinced. However, I would bet that with the extra care and attention lunar gardeners give their gardens, the gardens benefit whether the success is due to the Moon or not."

For more information on the ideas behind lunar gardening check out Caren Catterall's site, Gardening by the Moon.

Here is another interpretation, from an individual who tested to see if moon planting made any difference in the success of crops, from Undeceiving Ourselves:

"Gardening folklore in general is often based on accurate observation. It's just that the reasoning may be faulty. For example, over the years I've tested various bits of 'companion planting' folklore. And some actually work, but not because 'basil likes tomatoes' (which actually doesn't work because basil planted near tomatoes tends to get black spot, while the tomatoes do neither better nor worse). Never trust a gardening book that tells you that marigolds deter aphids--beans, onions and fuchsias planted with marigolds get more aphids, not fewer, and I suspect the same is true of other plants. On the other hand, root knot nematodes do appear to avoid the root secretions of marigolds, though a companion crop of marigolds can make the problem worse for other reasons. So remember that a gardening observation (like Moon planting) may be true even though the reasoning is faulty."

There are journal articles which discuss lunar gardening. Here are a few:

  • Weird or wonderful? (organic farming) by Paul Kingsnorth in The Ecologist,February 2008. Abstract: Different kinds of gardening techniques have come up like planting according to the phases of the moon that promises higher yields and better flavors. There is also biodynamic growing that claims to be founded on a holistic and spiritual understanding of nature.
  • La lune et la nature vivante (The moon and living nature) by Lucien Baillaud in Revue des Sciences Naturelles d'Auvergne, 2003. Abstract: Popular traditions regard the effect of the moon on plants. Patented researchers strive to track lunar influences without a known functional rule: many people of the sciences disagree with their results. These questions present themselves in very diverse manners to those who observe nature, to those who cultivate their gardens, or to those who try to reason.
  • Fractured Physics by Lynne Johnson in The Physics Teacher, Vol. 32, May 1994
  • Lunar Gardening: common sense or lunacy? by Kat Neely Jones in GreenPrints, Summer 2007
  • Lunar-Sidereal Rhythms in Crop Yield: A Review by Nicholas Kollerstrom and Gerhard Staudenmaier in Biological Agriculture and Horticulture, 2001, Vol. 19, pages 247-259. Online version.

The book The Old Farmer's Almanac Book of Garden Wisdom by Cynthia Van Hazinga (Random House, 1996) also has a brief discussion of gardening by the phases of the moon, and mentions it as a principle of biodynamic gardening. The following information on biodynamic gardening comes from National Sustainable Agriculture Information Service's resources (no longer available online), excerpted here:

"Planetary Influences

Lunar and astrological cycles play a key role in the timing of biodynamic practices, such as the making of BD preparations and when to plant and cultivate. Recognition of celestial influences on plant growth are part of the biodynamic awareness that subtle energy forces affect biological systems. A selection of resources are listed below. On examination of the variations in agricultural calendars that have sprung from the biodynamic experience, it is apparent that differing viewpoints exist on which lunar, planetary, and stellar influences should be followed.

Stella Natura - The Kimberton Hills Biodynamic Agricultural Calendar (...) is the biodynamic calendar edited by Sherry Wildfeur and the most prominently known calendar of this type in the United States. It contains informative articles interspersed with daily and monthly astrological details, and lists suggested times for planting root, leaf, flowering, and fruiting crops.

Working with the Stars: A Bio-Dynamic Sowing and Planting Calendar (...) is the biodynamic calendar based on Maria Thun's research and is more prominently used in Europe. Of the three calendars mentioned here, Thun's calendar relies more heavily on planetary and stellar influences. It contains research briefs as well as daily and monthly astrological details, again with suggested planting times.

Astronomical Gardening Guide, available through Agri-Synthesis in Napa, California for a self-addressed stamped envelope, is the biodynamic gardening guide compiled by Greg Willis of Agri-Synthesis. This calendar, which is a simple 2-sheet information leaflet, focuses on lunar phases."

Date 2018-06-19
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Plant Answer Line Question

Keywords: Lathyrus odoratus, Plant phenology, Pisum, Planting time, Syringa

It's already the middle of March and I'm worried that our soil is still too cold to plant peas (both edible and sweet). When is the correct time to plant them in the Seattle area?


Since weather patterns vary from year to year, it may make more sense to plant based on something other than the calendar date. An old adage says that it is time to plant peas when the lilac leaves are the size of a mouse's ear. This may sound quaint, but it turns out that the growth cycle of the lilac (Syringa) is an excellent indicator of temperature. Phenology is the science concerned with the timing of specific biological events, and lilac is among the plants often studied. Project BudBurst has additional information about phenology and climate change. The U.S. National Phenology Network is also a good resource.

If you don't have a lilac in your garden (or a mouse's ear, for that matter), Washington State University Extension says that a safe time for planting peas is usually mid-March, not so much because of soil temperature, but because in February the soil is often oversaturated, and your peas would rot in the ground.

Date 2017-08-24
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May 31 2018 13:14:08