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Elisabeth C. Miller Library

Keyword: Seeds

last frost dates

This year is my first in a house with a yard. I’m very
excited to try my hand at growing some food this year. Many of my seed packets say to plant after the last frost or when the soil reaches certain temperatures. Having never planted anything at the beginning of a season before, I
have no idea when any of these temperatures happen around here! Can someone give me some temperatures and approximate times when they are normally reached?

 

The last frost date in Seattle can be as early as
March 22, but to be on the safe side, April 15-20 would be more
definitive. This information(now archived) can also be found on the web site of local
gardening expert, Ed Hume. The web site also provides further details. Excerpt:
“The last frost date for an area is the last day in the spring that you could have a frost. The average last frost day is the date on which in half of the previous years the last frost had already occurred (so about half of the time it will not frost again and it will be safe to plant tender plants). Most planting directions are based on the average last frost date. The calendar based directions I give (Now it is time to… etc.) are usually based on an average last frost date of April 1st.

An important thing to realize about last frost dates is that the actual date of the last frost is different every year. It can be much earlier than the average or much later. This is especially important for tender plants that can be killed by a frost. For hardier plants, the average last frost date is more an indicator of general growing conditions than a danger sign.”

The closer to the water the garden is, the milder the temperatures.
The moderating effect of Puget Sound or Lake Washington, for instance,
which results in milder winter temperatures, extends inland for some
distance. If your garden is more than a mile or so from water, that
moderating influence could vary. The last frost date for Vashon Island is
April 5; for the Sea-Tac area, April 9. Again, add at least a week and
check your own garden temperatures and patterns.

propagating black mondo grass from seed

Last year, I collected and propagated seed from my black mondo grass. I now have about a hundred healthy starts which are green in color, with leaves thicker than those of the parent black mondo plants. Is this just their immature color, or do they not come true from seed?

 

Most of the resources I consulted recommend propagating Ophiopogon planiscapus ‘Nigrescens’ by division of clumps in fall or late winter, but The Plantfinder’s Guide to Ornamental Grasses by Roger Grounds (Timber Press, 1998) says the following:
“The flowers are mauve, but the berries are black, and if sown will produce about one-third black seedlings, the rest being green.”

If all of your plants came up green, I would guess they will stay that color (in other words, they must have reverted to the species, Ophiopogon planiscapus, which has wider green leaves).

harvesting columbine seeds

When and how should I harvest Aquilegia formosa (columbine) seeds? My plant is long past bloom and the seed pods are drying out. Should I harvest the pods or seeds? Harvest them now or wait until they dry out?

 

According to Propagation of Pacific Northwest Native Plants by Robin Rose (Oregon State University Press, 1998), Aquilegia formosa seeds can be harvested “from June to August […] as soon as the seeds heads are dry and come off easily by hand. Gently crush the dried heads to release the remaining seed […] Seeds can also be collected by cutting the fruiting stalk and placing in a bag before the follicles open. Dry the follicles in the bag for a few days and separate the seeds by shaking the bag.”

on collecting Yucca seeds

I live in New Mexico, and I’d like to harvest Yucca seed to share with the local cactus and succulent society. Last time I tried, I didn’t find any seeds at all. I want to go about this the right way–can you tell me what I should do?

 

In searching for an answer to your question about how and when to collect seed from Yuccas, I came across several articles on the interdependence of Yuccas and Yucca moths. Here is one example (now archived), from Emporia State University:

Excerpt:
“… the yucca plant and yucca moth are the textbook case of coevolution. First, the yucca plant has no ability to reproduce seeds without the moth. Yuccas can propagate small rosettes around the parent plant, but these vegetative sprouts are copies of the parent. Over decades, the plant cannot move but a few feet, and there is no possibility for genetic variation. Without the moth, the whole flowering effort (expensive to the plant in energy terms) is a total waste. The only pollinator of the plant is the yucca moth; bees are not attracted and neither wind nor bees can pick up the sticky pollen.

The yucca moth is likewise dependent upon the yucca plant. There are no alternate host plants known for the yucca moth; the yucca moth caterpillars must eat yucca seeds or starve. Without the plant, the moths die off in one generation. Without the moth, the plant cannot reproduce variation or disperse; given any major climate changes, it too will go extinct. The system is therefore tightly coevolved.[…] You can watch yucca moths pollinate flowers between dusk and midnight. The female gathers pollen from the flower anthers by using her specially adapted mouthparts, called palps. She forms the sticky pollen into a ball which she carries between her tentacles and her thorax (under her “chin” so to speak). The pollen ball is then “stuffed” or “combed” into the stigma of the various flowers she visits. The stigma is the receptive tip of the female pistil. Without this process, the yucca flower will not develop into the fruit or pod with seeds.”

The Arizona-Sonora Desert Museum states that Yucca may not set seed every year:

“Biologists have only recently determined that almost every species of yucca has its own species of yucca moth; some yuccas have two moth species. Such a tight mutualism has risks for both partners. Emergence of adult moths must coincide with yucca flowering for the reproductive needs of both species to be met. However, the synchronization of moth emergence with flowering is frequently poor and seed set and moth reproduction in such years are low. Furthermore, yucca populations may flower sparsely or not at all in dry years. Yuccas don’t have to set seed every year because they flower many times in their long lives.”

Regarding seed collecting and preparation, a question similar to yours was answered by the Lady Bird Johnson Wildflower Center:

“Gather capsules as they begin to dry but before they split. Allow to dry, then crush to remove seeds. Overwinter, keep seeds in moist sand in the refrigerator. For longer storage periods, keep in sealed, refrigerated containers.

At the Lady Bird Johnson Wildflower Center, we have collected and prepared yucca seeds for the Millennium Seed Bank. Crushing the pod to remove seeds is not as easy as it sounds. We found that pliers worked about as well as anything, but it was a struggle, either way. Inside the broken pod, you will find channels of seeds. They are flat, black wafers, very thin. As you pull out a stack of them, you may find a neat, round hole drilled up the center. This is the nursery for the larvae of the yucca moth, who have been munching on the seeds. However, the yucca moth is essential for the blooming of the plant.”

Late summer to early fall (September/October) seems to be the time when some Yucca seeds ripen. Several places I looked suggested this is the case, including Plants for a Future database, which describes propagation for several species of Yucca.

growing huckleberries from seed

I live in the UK, and I have been given some of your Huckleberry seeds. Can you advise me on how to grow huckleberries from seed?

 

I am guessing that you mean that you have seed for one of the native
Pacific Northwest huckleberries, such as the evergreen (Vaccinium
ovatum), or red huckleberry (Vaccinium parvifolium). It would be helpful to know which species you are hoping to grow from seed.

The website of Plants for a Future has propagation information for propagating Vaccinium species in general:

Seed – sow late winter in a greenhouse in a lime-free potting mix and
only just cover the seed. Stored seed might require a period of up to 3
months cold stratification. Another report says that it is best to sow
the seed in a greenhouse as soon as it is ripe. Once they are about 5cm
tall, prick the seedlings out into individual pots and grow them on in a
lightly shaded position in the greenhouse for at least their first
winter. Plant them out into their permanent positions in late spring or
early summer, after the last expected frosts.

Here are additional links to information:
Evergreen Huckleberry, or Vaccinium ovatum

Red Huckleberry, or Vaccinium parvifolium

Apparently, growing our native huckleberries from seed is challenging, as
the information cited here, from a propagation course at the University
of Washington, indicates: “Evergreen huckleberry can be propagated
through hardwood cuttings or by seed, however seedling establishment is
rare in most Western huckleberries.”

The United States Department of Agriculture has this to say:

Seeds of most Vaccinium spp. are not dormant and require no pretreatment for germination. Seedlings first emerge in approximately 1 month and continue to emerge for long periods of time in the absence of cold stratification.
However, seedlings of most western huckleberries are rarely observed in the field. Seeds of evergreen huckleberry usually exhibit fairly good germination under laboratory conditions, but early growth is generally very slow.

on sourcing seeds of PNW plants

Where can the public, not agencies, purchase seeds of Pacific Northwest plants? A Missouri school teacher would like to sprout them in her classroom.

 

Once the teacher has a list of plants she is seeking (a list which could
be developed by looking at books on Pacific Northwest native plants, or
by visiting some of the sites linked below), there are a number of ways
of finding sources, shown below.

Washington Native Plant Society’s list of plant and seed sources

More lists of plants:

Native Plant Resources for the Pacific Northwest

Native Plant List –
Western Oregon and Western Washington

Plant Information Online – search once you have specific plants in mind.

Businesses which specialize in native plants:

Native Plant Nurseries
in Washington State

Nurseries – Washington

Garden Tip #50

A book by Jekka McVicar called Seeds: the ultimate guide to growing successfully from seed (Lyons Press, 2003, $22.95) will help you turn your seedy hopes into plant reality. Thirteen chapters are divided by types of plant including ferns, grasses, shrubs, perennials and herbs. The practical information that applies to all kinds of seeds, such as what type of soil to use, and how to break seed dormancy, is included in the last chapter. Color photos illustrate throughout.

For online tips for seed starting go to:
http://cru.cahe.wsu.edu/CEPublications/pnw0170/pnw0170.pdf from Oregon State University.

RHS Plants from Pips: Pots of Plants for the Whole Family to Enjoy

rhs plans from pips book jacketWorking in the kitchen, have you ever wondered whether you could grow peppers from pepper seeds? How about a mango tree from a mango pit? This book for gardeners of all ages explains how to germinate a wide range of commonly-seen seeds most people would usually toss in the bin. The entries detail what each plant would need to grow on to maturity, while an illustrated section at the end highlights basic gardening techniques as well as common problems and solutions.

Published in the August 2015 Leaflet Volume 2, Issue 8.