Plant division and propagation

I am wondering if the following plants can be divided or propagated successfully: Heuchera, Donkey Tail Spurge (Euphorbia), Corsican Hellebore, and Helianthemum.

I consulted The American Horticultural Society Plant Propagation book,
edited by Alan Toogood (DK Publishing, 1999), and it says the following:

Heuchera: by division or by seed in spring. Since cultivars may not
come true from seed, I would recommend dividing your plants. Once spring
growth has begun, lift the plant from the ground and remove small
sections from around the edge (look for good roots, and 2-3 shoots).
Euphorbia myrsinites: (Just a note: based on the USDA information that
this plant is invasive in Oregon and banned in Colorado, I would think twice before propagating it. This species does a fine job of propagating itself, apparently. In general, the genus Euphorbia can be propagated by division in early
spring, or from spring to summer, by seeds in fall or spring, and by cuttings in summer or fall, but if you were to propagate by cuttings, you would need to protect your skin from the sap.
Helleborus argutifolius can be propagated by division after flowering,
or by seeds in summer. Test seed capsules for readiness by gently
squeezing. If the seed capsule splits to reveal dark seeds, it is ready
for harvest. Wear gloves! H. argutifolius (Corsican hellebore) often
self-seeds. Check around the base of the plant in spring. When each
seedling has at least one true leaf, gently lift and transplant to moist,
fertile soil in light shade.
Helianthemum can be started from greenwood cuttings rooted in summer
and fall, and by seeds sown in spring in a frost-free location.

If you would like further information on the relative ease or difficulty
of each of these methods for each of these plants, I recommend coming to
the Miller Library and looking at our books and other resources on
propagation. Here is a link to a booklist.

Euphorbia, Helianthemum, Helleborus, Heuchera, Invasive plants, Propagation

Growing Gingko trees from seed

How can I grow a ginkgo tree from seed?

According to the American Horticultural Society’s Plant Propagation (DK Publishing, 1999), seeds may be sown in late winter. Gather the ripe fruit of the female tree in mid-autumn, and clean off the pulp. Then wash the seeds with mild soap to remove germination inhibitors, and store the seeds in the refrigerator for 30 to 60 days before sowing outdoors in containers. Here is more information from Plants for a Future:

“Seed: best sown as soon as it is ripe in a cold frame or in a sheltered outdoor bed. The seed requires stratification according to one report whilst another says that stratification is not required and that the seed can be sown in spring but that it must not have been allowed to dry out. Germination is usually good to fair. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in light shade in the greenhouse for their first year. Plant them out into their permanent positions in the following spring and consider giving them some protection from winter cold for their first winter outdoors.”

The Ginkgo Pages website also has useful propagation information.

Storing and germinating seeds

Last year I collected several hundred seeds from our local native columbine (Aquilegia formosa) in Thurston County. I recently planted some in commercial seed-starting mix in my small greenhouse. Could you tell me the best methods for storing and germinating these seeds as well as some of the native tiger lily?

In general, seeds should be stored in a dark, dry, cool place. I have had good luck storing extra seeds in a sealed jar or bag in the refrigerator, but this is not always recommended, because it is damp. According to Seeds by Jekka McVicar, columbine seed is generally viable for five years. McVicar suggests placing flats outside in fall and leaving them out all winter, since the cold helps to prepare the seeds for germination in spring. Alternatively, “in late summer fill tray or pot with compost, smooth over, tap down, and water in well. Use fresh seed (…) sowing the seed thinly on the surface of the compost. Cover with perlite or vermiculite (…)Place the tray or pot in a warm place out of direct sunlight at an optimum temperature of 50 degrees. Keep watering to a minimum until germination has occurred, which takes 14-28 days with warmth. Prick out into pots. (…) Overwinter young plants with a bit of protection in a cold frame.”

Eileen Powell, author of From Seed to Bloom, suggests refrigerating the seedling trays for two to three weeks and then sinking the flats into the ground in a shady location, covered with glass, and transplanting seedlings as they appear. She also says “seedlings are delicate; keep out of strong sunlight and water gently.”

Neither of these authors discusses our native columbine. However, Propagation of Pacific Northwest Native Plants by Robin Rose et al. suggests an easier method for Aquilegia formosa: “Seeds can be stored for up to two years at a low temperature and humidity or longer in sealed containers in low moisture. Prechilling for three days is required for germination. Direct seed in spring or fall. (…) Plant in containers or scatter evenly over a seedbed (this is made easier by first mixing the seeds with fine sand). Cover with a very thin layer of soil or weed-free compost and keep moist. Seeds should germinate in two to four weeks.”

As for propagating the native tiger lily, Lilium columbianum, Plants for a Future database provides directions, excerpted here:
“Seed: autumnal hypogeal germination. Best sown as soon as ripe in a cold frame, it should germinate in spring. Stored seed will require a warm/cold/warm cycle of stratification, each period being about 2 months long. Grow on in cool shady conditions. Great care should be taken in pricking out the young seedlings, many people leave them in the seed pot until they die down at the end of their second years growth. This necessitates sowing the seed thinly and using a reasonably fertile sowing medium. The plants will also require regular feeding when in growth. Divide the young bulbs when they are dormant, putting 2 – 3 in each pot, and grow them on for at least another year before planting them out into their permanent positions when the plants are dormant. Division in autumn once the leaves have died down. Replant immediately. Bulb scales can be removed from the bulbs in early autumn. If they are kept in a warm dark place in a bag of moist peat, they will produce bulblets. These bulblets can be potted up and grown on in the greenhouse until they are large enough to plant out. Stem or leaf cuttings.”

Here is what Kathleen Robson et al. have to say in Encyclopedia of Northwest Native Plants for Gardens and Landscapes (Timber Press, 2007): “Propagation: collect seeds in the late summer after capsules have ripened. Plant them within a few weeks of harvest, either directly into the garden or into deep containers, and leave them outside in the cool, moist winter weather for germination the following spring. Seedlings will take several years to reach flowering size. Those that were sown in containers can be left in them for part of that time; it may be easier to protect them from slugs.”

growing and propagating lupines

I moved to New Hampshire from Missouri and want to grow lupines.
Having purchased some plants, I have enjoyed many blooms. After the
bloom, the flower turns into what looks like a pod with seeds. Can I
replant those seeds in order to propagate them for next year, or when is
the best time to plant them? Also for the remaining foliage on the
plant, what should I do to maintain it? Continue to water it and give it
MiracleGro for nutrients?

According to the American Horticultural Society’s Plant Propagation edited by Alan Toogood (DK Publishing, 1999), lupines may be propagated from seed between early and mid-spring. (Other methods of propagation
include stem cuttings taken in mid- to late spring). Lupine seeds
require some special treatment, as described by the Sustainable Urban Landscape Information Series (formerly available online from University of Minnesota):

“Moisture is important to seed germination. Some seeds are protected by a
tough seed coat. Some must be soaked in water to soften the seed coat
prior to germinating. Other seeds must have their seed coat nicked or
pierced (scarified) in order to allow moisture to reach the seed, causing
it to expand and break through the seed coat; two examples are in the
legume family – sweet peas (Lathyrus species) require soaking, and lupine
(Lupinus species) require scarification.

The following information from University of Washington should apply to
your lupines, not just our native lupines. It suggests collecting seed from June to August, storing the seed in the pods inside paper bags, and then scarifying them prior to soaking and sowing (in spring or fall).

Lupines should do well in zones 3 to 8, depending on the species. More
information on growing hybrid lupines can be found here, including
suggestions on fertilizing. Choose a complete slow-release organic fertilizer instead
of synthetic fertilizers like MiracleGro, which may be too high in nitrogen.

When flowering is finished, you can cut the plants down to the ground, and you
may still see a second burst of growth. There is no need to water when the plant
is not in active growth. (In our Northwest climate, the leaves tend to
look mildewy by this time of year, and you would want to cut them back
anyway). Rainyside Gardeners, a Pacific Northwest website, has additional information.

propagating crimson glory vine

I am having difficulty propagating Vitis coignetiae. The cuttings are
not taking. Any advice?

Here is what I found in the Plants for a Future Database:

Seed – best sown in a cold frame as soon as it is ripe. Six weeks cold
stratification improves the germination rate, and so stored seed is best
sown in a cold frame as soon as it is obtained. Germination should take
place in the first spring, but sometimes takes another 12 months. Prick
out the seedlings into individual pots when they are large enough to
handle and grow them on in a cold frame for their first winter. Plant out
in early summer.

Cuttings of mature wood of the current seasons growth, December/January
in a frame. These cuttings can be of wood 15 – 30cm long or they can be
of short sections of the stem about 5cm long with just one bud at the top
of the section. In this case a thin, narrow strip of the bark about 3cm
long is removed from the bottom half of the side of the stem. This will
encourage callusing and the formation of roots. Due to the size of these
cuttings they need to be kept in a more protected environment than the
longer cuttings. Cuttings are difficult from this species.

Layering: This is the best method for this species.

See the Royal Horticultural Society for general layering information.

plant propagation and rooting hormones

1. Which plants can be rooted only with hormone?

2. Which plants cannot be rooted, even with hormone?

There is excellent general information on plant propagation in The Brooklyn Botanic Garden Gardener’s Desk Reference (Janet Marinelli, editor; Henry Holt, 1998), which explains which plants are most successfully propagated by seed, by division, by layering, by leaf or hardwood or softwood or stem cuttings, and by root cuttings.

There really is no resource that will provide a comprehensive list of plants that can or cannot successfully be propagated from root cuttings, but a member of the faculty here who specializes in propagation says that the key element that determines whether a plant can be propagated in that way is age. Each plant has different abilities, and some are easily rooted, such as Salix (willow), while others, like Quercus (oak), or Arbutus (madrona), are very hard to root, especially as they mature. As far as use of rooting hormone, it can help the process, and it will prevent rotting, but if you are a strictly organic gardener, you should be aware that it is a chemical substance.

rooting hormones and other alternatives

What is the purpose of the chemical in store-brand rooting hormone? I’d rather not use anything with chemicals when I’m propagating plants. Are there alternatives?

The chemical in rooting hormone (usually Indole-3-Butyric acid) acts as a growth stimulator. In commercial rooting hormone formulations, it may be combined with fungicide to prevent the development of fungus/fungal diseases during the rooting process, as is the case with a common brand, Rootone, which contains Thiram (a fungicide). The Environmental Protection Agency has more information about Indole-3-Butyric acid.

If you would rather not use synthetic rooting hormone, you can skip this stage altogether, or you can try making willow water to encourage rooting instead. Oregon State University (now archived) explains how to make a rooting tonic using willow.

propagating Stipa

Can ‘Giant Feather Grass’ (Stipa gigantea) be propagated by division or by seed only? What are the requirements for successful propagation?

You can propagate Stipa either by division or by seed. According to the A-Z Encyclopedia of Plants and the AHS Plant Propagation books, both ways need to be done in the spring. Specifically, seeds should be sown in containers in a cold frame in spring. Divisions should be done from mid-spring to early summer.

Seeds should be sown when you can maintain a temperature of 59 degrees F. Most grass seed germinates in a week. Transplant seedlings one to a pot or cell as soon as they are large enough to handle. Transfer pots of established seedlings to a frost-free place to grow. Plant out in mid-spring.

Divisions – cut back the foliage for easier handling, then lift the clump. Shake loose soil from the roots or wash clean, to make it easier to separate them. Use a sharp knife to divide the clump into good-sized sections. Trim any overlong or damaged roots. The divisions can then be replanted in the garden.

I have also noticed that in my garden, Stipa usually reseeds itself and if you look carefully you may find some small seedlings already started, which you can transplant.

propagating and grafting Ginkgo biloba

Onto what root stock should I graft a Ginkgo biloba scion?

According to The Complete Book of Plant Propagation (Taunton Press, 1997, Jim Arbury et al.), Ginkgo biloba can be propagated without grafting, by taking semi-ripe cuttings in midsummer and dusting them with rooting hormone and potting them up in a mixture of half peat, half sand/vermiculite. Cuttings should root by spring if kept moist, and need to be planted out once they have roots.

If you wish to graft it, you need a Ginkgo biloba rootstock, which you could grow from seed if you have access to a female ginkgo tree (they are hard to find), and (according to the American Horticultural Society Plant Propagation manual) you can use a whip-and-tongue or spliced side veneer graft done in late winter. The AHS manual also recommends taking softwood cuttings in late spring or early summer for ginkgo.

There is also helpful information from The Ginkgo Pages and Plants for a Future Database, which says that softwood cuttings are taken in spring, semi-ripe cuttings are taken in July and August, and hardwood cuttings are taken in December, and all are kept in a frame.

growing Hibiscus from cuttings

Can you tell me how to grow Hibiscus from cuttings?

According to the American Horticultural Society, most hibiscus root easily from cuttings. They suggest the following in Plant Propagation (1999, p. 131 and pp. 100-101):

“…cuttings should usually be 1.5 to 2 inches long, with two or three pairs of leaves retained at the top…remove the soft tip from each cutting, because it is vulnerable to both rotting and scorch…remove the lowest pair of leaves to make it easier to insert the cutting into the medium…make a hole in the medium with a pencil…[for]…minimal resistance…the cuttings will benefit from a warm, protected environment…when the cuttings root, knock them out of the container and gently pull them apart. Pot singly…”

The AHS suggests using rooting hormone and they also point out that due to timing, you may get ‘greenwood’ (slightly hardened) rather than ‘softwood’ cuttings; they are treated the same way.

North Dakota State University Extension has propagation directions including from cuttings.

I also looked at Houzz (formerly GardenWeb), a gardening forum where experienced gardeners share their knowledge. Here is another link from this site which suggests layering, a process by which you bend a branch down to soil (usually in a pot), anchor it, and wait for it to take root.

Here is additional information about layering hibiscus, from Hibiscus World.