Finish Transplanting Before Winter Ends

90220thumbAutumn is for planting; and for good reasons. It is the beginning of dormancy for almost all plants, including evergreens. It precedes cool and rainy weather that inhibits desiccation until new roots are able to disperse sufficiently to sustain new plants. Some plants need to be in the garden in time for winter chill in order to initiate bloom. However, not everything should get planted in autumn.

Winter is the best season for some plants. Many summer blooming bulbs get planted in winter because they are likely to start growing prematurely and get damaged by frost if planted in autumn with spring bulbs. Some perennials that are slightly sensitive to frost may get planted after average frost season so that they can bulk up enough to be more resilient to frost by the following winter.

Besides new plants that are purchased from nurseries to be planted in the garden, there are plants that are already established in the garden that might need to get dug, divided, and then planted back into the garden, or shared with friends and neighbors. Some might need to be transplanted because they are crowded or in the way of something. These present a different set of variables.

Once divided and transplanted, grasses, New Zealand flax, lily-of-the-Nile, African iris and other stoloniferous perennials (that spread by creeping stems known as stolons) are more susceptible to rot than nursery grown plants, because so many of their roots get severed. Even if aggressively pruned while getting divided and transplanted, shrubby plants, like lilac and forsythia, are more susceptible to desiccation than nursery grown plants, simply because they lack sufficient roots.

If divided or transplanted through winter rather than autumn, plants get a few weeks of cool and rainy weather to settle and disperse their roots, but do not have enough time to rot or desiccate before the weather gets warm enough for them to resume growth and recover resiliency. Perennials that get cut back in the process spend less time looking shabby before new growth develops.


Plant Bare Root Plants Properly

90206thumbCompared to canned (potted) nursery stock, bare root plants have a few advantages. They are less expensive, easier to handle, more conducive to pruning into a desired form, and they disperse roots and get established more efficiently. One more advantage that is not often considered is that they are easier to install into the garden. For some, it is as simple as poking a stick in the mud.

Perhaps the only disadvantage of bare root plants is that they must be planted immediately, so that they get their roots soaked and settled into the ground into which they will disperse new roots. If planting must be delayed, roots can soak in a bucket of water for only a few days. Unless they are to live in big pots, potting for a season only delays and interferes with efficient root dispersion.

Only bare root trees that need root barriers (to divert roots from pavement) or mesh gopher baskets (to divert gophers from roots) will need planting holes that are as big as those for canned nursery stock. Otherwise, planting holes need be only as wide as the bare roots, and should be no deeper. If soil is loosened too deeply below, new plants will sink as loose soil settles. Graft unions must remain above grade.

Well flared roots can be spread over a cone of soil formed at the bottom of the planting hole. Conversely, cane berries, after their roots get loosened, can simply be dropped into slots formed by sticking a shovel into the ground and prying it back.

Soil amendments that are useful for providing a transition zone between potting media of canned nursery stock the surrounding soil are not so important with bare root stock. Bare root plants only want a bit of soil amendment if the soil is too sandy or too dense with clay. Otherwise, too much amendment can actually inhibit root dispersion by tempting roots to stay where the richest soil is.

Once planted, trees can be pruned as desired. Most come with superfluous stems to provide more options for pruning, and some stems will be damaged in transport. Fertilizer need not be applied until growth resumes in spring.

Six on Saturday: Deodar Cedar Migration


Deodar cedars that were featured in the gardening column about two weeks ago, , live in a small grove adjacent to a building that I work out of. They need a bit of pruning for clearance from the roof, but are otherwise rather nice and healthy specimens.

They are also prolific. Quite a herd of seedlings is developing on the ground below. None of the individual seedlings are more than just a few years old, which suggests that the area was cleared of seedlings a few years ago. The area needs to be cleared of seedlings again, before they grow big enough to become a messy thicket.

Part of another landscape in another area happened to be in need of a few deodar cedars. There were two established specimens there already. They suit the situation so well that more are desired. However, new trees are expensive, and because there is no irrigation system in that particular site, they would need to be watered very regularly by hose until they get established.

Well, you can guess what happened. We pulled up several of the seedlings that needed to be pulled up anyway, and simply plugged them into the site where more deodar cedars are desired. It was done just prior to rain, so the relocated seedlings did not even need to be soaked in. They were pruned so that they would not desiccate so readily. We planted way more than necessary because there were plenty to spare, and also because we expect that several will not survive the process. We also expect that we will likely need to cut down a few later because, although some will not survive, too many probably will. Because they are just tiny seedlings, they will get established more efficiently than canned nursery stock, and will not be so sensitive to lapses of irrigation.

Although way more than necessary were relocated, they were not even a quarter of what was available in the original herd. More than three quarters of the herd remain available to be planted elsewhere. More will likely be relocated to other parts of other landscapes before the rainy season is half way finished. A few will be canned and put into the nursery. Whatever we do to them should be done in the early part of the rainy season to take advantage of the weather while they get established. We prefer to relocate the larger seedlings first, so that those that remain will be the smaller seedlings that will take longer to get too big to move if they must wait until next year to be relocated.

This is actually old technology, and how tree seedlings were pulled and plugged to enhance the production of woodlots since ancient history. While undesirable seedlings were pulled and discarded, more desirable seedlings that happened to be crowded around the parent trees were pulled up and plugged in more uniformly over a larger area.

1. seedlings in the ground below the parent treesP81215

2. parent treesP81215+

3. bundle of seedlingsP81215++

4. unpruned seedlingP81215+++

5. same seedling prunedP81215++++

6. seedling in new locationP81215+++++

This is the link for Six on Saturday, for anyone else who would like to participate:

Propagation Of Perennials By Division

80718thumbAutumn is for more than planting. It is when most of the aggressive pruning gets stared. It might be the best time to work with compost and conditioning the soil. Bulbs get planted. Gutters get cleaned. Leaves get raked. Perennials get groomed. We might think of it as a time of slowing down after such a busy summer, but in many gardens, autumn is just as busy with seasonal chores.

Autumn is when many of the spring, and some of the early summer, blooming perennials get divided. That means that they get dug up, split into smaller parts, and then replanted. Because there will be more smaller plants after the process than there were bigger plants before the process, some should get planted over a larger area, in other parts of the landscape, or shared with friends.

Not all perennials need to be divided annually, and some may never need to be divided at all. Perennials that bloom in autumn or winter, such as Japanese anemone and bergenia, get divided in spring, since they will have plenty of time to recover from the process to bloom on schedule. Black-eyed Susan does not likely care if it gets crowded, but can get divided simply for propagation.

Lily-of-the-Nile should be divided if it gets too crowded to bloom well. Division allows more room for the individual shoots to grow and bloom as they should. However, because it takes a while for newly divided shoots to recover, they should only be divided every few years or so, and only if they happen to be getting crowded. African iris gets divided if overgrown plants are looking shabby.

It is not always necessary to dig entire plants. If dividing New Zealand flax just for propagation, it is easier to pry the desired number of side shoots from a mature clump, without digging the main part of the clump. Agave pups might be (very carefully) pried off of larger rosettes just to keep the main rosettes neat. Black-eyed Susan and other deciduous perennials get divided while bare.

Straight And Narrow For Trees

30731thumbIn the wild, trees do just fine without any help from anyone else. They certainly are not stupid. Their roots disperse for adequate stability. Their trunks grow upward as limbs spread outward for adequate structural integrity. Trees only need help in landscape situations because they are expected to perform so unnaturally. From the very beginning, their trunks are bound and their roots are confined.

While they are growing in the nursery, trees are bound tightly to stakes to keep their trunks straight. Unfortunately, this binding inhibits natural development of trunk caliper. Since they can rely on stakes for support, trees do not waste resources on developing the strength of their own trunks. The various eucalypti are particularly sensitive, and can bend over to reach the ground when unbound.

Roots are confined to cans (pots) or boxes because that is how trees are grown in the nursery. Even in regions where trees are field grown, roots must be severed when trees get dug and moved. Many types of trees do not mind much, and are eager to disperse roots into a new landscape as soon as possible. However, oaks, pines and many others do not recover as efficiently from confinement.

Once in a new landscape, most trees need to be staked to recover from being staked and confined in the nursery. New sturdier stakes that extend below the confined root system into soil below should stabilize newly planted trees. This is particularly important for evergreen trees that will be blown more by wind than bare deciduous trees, and particularly because most trees get planted in autumn and winter.

These new stakes should be installed a few inches away from the tree trunks so that they can support the trunks loosely when the tightly binding nursery stakes gets removed. To prevent abrasion, new straps should be somewhat loose, and cross over between the trunks and stakes. A pair of opposing stakes, with straps supporting in opposing directions, is sturdier than a single stake. A few straps may be necessary.

The new crepe myrtle trees in the picture above remain  bound to the stakes that they were grown with in the nursery. Sturdier stakes that can support the trunk in a less constrictive manner have yet to be installed.

Plan Ahead For Coniferous Evergreens

81031thumbWe all know what autumn is for. Planting, of course. Yes, it is a recurring theme; but there are so many different things to plant. Dormant bulbs need to get into the ground before cool and rainy winter weather. Deciduous plants that should be planted while dormant prefer an early start if planted as soon as they defoliate in autumn. Believe it or not, most evergreen plants are no different.

Evergreen plants do not experience the degree of dormancy that defoliated deciduous plants do, but they too are significantly less active during autumn and winter than they are during warmer weather. Therefore, if possible, they should also be planted in autumn, so that they can begin to slowly disperse roots through winter, to be ready to resume growth as weather warms next spring.

All planting should be planned. This is more important for trees, big shrubbery and other plants that are difficult to relocate once they have dispersed their roots. Some broadleaf evergreens that get bigger than expected can be pruned into submission. However, most coniferous evergreens are notoriously difficult to contain if they get too big for the situations into which they get planted.

‘Coniferous’ plants are those that produce cones. Cypress, pine, fir, spruce, cedar and redwood are the more familiar coniferous trees. Most coniferous trees, except for most of the various cypress, have excurrent branch structure, with lateral limbs extending from a central trunk. They can not be pruned down without disfiguring their central trunks. Lateral limbs can be disfigured if pruned back. Such trees should therefore be planted where they can grow unobstructed to mature size.

Juniper and arborvitae are some of the more familiar of coniferous shrubbery. They can be shorn even into formal hedges, but only if shorn very regularly. Their dense foliage shades out interior foliage. If they get too big for the respective situations, they can not be pruned back into submission without exposing their bare interiors. Once exposed, bare interior stems may never recover.

Autumn Is For Planting – Especially Bulbs

81024thumbAutumn is for planting. Cliche? Yes; but true. Autumn is when most plants are beginning dormancy, and are therefore not so bothered by the discomforts associated with transplant. The weather is cooler and wetter, so that even if they are bothered, such discomforts are not as discomforting as they would be in summer. Once in the ground, plants have a few months to recover before spring.

The two main exceptions to the rule that ‘autumn is for planting’ are plants that are sensitive to frost, and bare root plants. Plants that are sensitive to frost should obviously be planted after the last frost date, at the far end of winter. Bare roots plants do not wait that long, but should wait until they are completely dormant in mid winter before being dug, separated from their soil, and relocated.

Dormant bulbs and bulb like plants, including corms, rhizomes, tubers and tuberous roots, epitomize the autumn planting rule. They must be planted while dormant in autumn or winter. They arrive in nurseries about the same time that they should be planted into the garden. Spring blooming bulbs become available and should be planted earliest. Summer bulbs become available a bit later.

Daffodil, narcissus, tulip, crocus, hyacinth, grape hyacinth, freesia, anemone, ranunculus, montbretia, crocosmia, most lily and some types of iris will all want to get into the ground when the rain starts. Rain leaching through the soil around them, as well as cooler temperatures through winter, tell them what time of year it is, so that they will be ready to bloom when weather warms in spring.

Each type of bulb prefers to be planted at a particular depth. Bearded iris rhizomes want to be buried horizontally, just below the soil surface. As long as the latest get planted within their respective planting season, some types of bulbs can be planted in phases every week or two, so that a later phase starts to bloom as an earlier phase finishes. Daffodil, narcissus and especially grape hyacinth have the potential to naturalize and bloom annually. Montbretia and crocosmia can be downright invasive.

Winter Dormancy Begins In Autumn

50923thumbAutumn is for planting . . . but not much else. While it is important to get certain new plants into the garden before cool and rainy weather, other gardening chores will not be necessary while plants are becoming less active before winter dormancy. Raking falling leaves is probably the biggest of the new chores that are specific to autumn.

Formal hedges that have been getting shorn regularly since spring may not need to be shorn again until next spring. They simply will not grow much between now and then. If possible, pittosporum and photinia should not be shorn once the weather gets rainy. Their freshly cut stems are more susceptible to certain diseases while wet than during dry weather.

Citrus and tropical plants should not be pruned late because pruning stimulates fresh new growth that will be susceptible to frost later in winter. Even if tender new foliage does not get frozen, it can get discolored and disfigured by cold weather. Cool weather inhibits vascular activity necessary to sustain the development of healthy new foliage anyway.

For the same few reasons, fertilizer will not be necessary later in autumn. Fertilizer can potentially stimulate new growth when it is not necessarily wanted. Also, some nutrients in fertilizer are less soluble (or chemically unavailable) while the weather is cool. Only plants that grow through winter, like cool season annuals, vegetables and grasses, will want fertilizer.

Planting is done in autumn because plants are either dormant or less active than they had been during warmer weather. They can take their time to disperse their roots into comfortably cool and damp soil. Evergreen plants do not draw as much moisture from their roots while foliage is cool and damp. Deciduous plants draw even less moisture without foliage.

Spring blooming bulbs get planted in autumn not only so that they can disperse their roots leisurely, but also because they need to get chilled to bloom well. Bulbs can be phased, so that those planted earlier will bloom before those of the same kind planted later. However, if planted too late, they may not get sufficient chill.

Division Is Equal To Multiplication

70809thumbMathematically, division is the opposite of multiplication. Horticulturally, they are the same. Digging and splitting overgrown perennials to propagate them is known as ‘division’ because it divides many rooted stems or rhizomes of one plant into many new plants. Division is a form of propagation; and propagation is commonly known as multiplication. So, we divide plants to multiply them.

Autumn is generally the best time for panting. It is after most of the warmest and driest weather, and just before the cool and rainy weather that keeps newly planted plants from getting too dry. It seems obvious that autumn would also be the best time for division. However, a few perennials that are dormant or mostly dormant by the middle of summer can be divided now for an early start.

Bearded iris may not look dormant with their leaves still green, but they are about as dormant now as they will get. If divided now and allowed to slowly disperse roots through the remainder of summer, they can prioritize the production of new foliage when they come out of dormancy in autumn, like they would do naturally. Like many perennials in mild climates, they grow through winter.

Once dug, the plump rhizomes need to be separated from the old shriveled rhizomes that they grew from. For most, the best segments of rhizome are between the leafy tips and the stalks of the flowers that bloomed earlier this year, although it may not be easy to see where floral stalks were attached. The older sections of rhizome behind the flower stems are probably shriveled already.

The freshly divided segments of rhizome should then be groomed of deteriorating old leaves. Remaining green leaves can be cut in half to remove drying tips. Rhizomes then get replanted just below the surface, with the perpendicular fans of foliage standing upright. The main difficulty with dividing iris now is that they will need to be watered until the rain starts late in autumn. Bergenia, lily-of-the-Nile and a variety of perennials with big rhizomes get divided in a similar manner.

Autumn Really Was For Planting

70531thumbIt is easy to see why there are optimum times to prune, and just as easy to see when pruning should not be done. Generally, deciduous plants prefer to get pruned while dormant and bare. They should not be pruned when actively blooming or making new foliage. Roots are of course not so easy to see. Do we really know what they are doing, or what sort of mischief they are getting into?

Autumn is the best time for planting most plants. They are less active than they had been earlier in the year, and many are going dormant. Either way, they do not need much. Once in the ground, their roots are kept cool and moist by the weather. They get to sit there all winter, as they slowly begin to disperse their roots to get ready for the following spring. It all fits into their natural life cycle.

Shopping habits, however, do not. By autumn, many plants are neither as pretty nor as tempting as they were earlier in the year. By winter, the weather keeps many of us inside, and out of nurseries. Now that it is spring, it is difficult to resist all the pretty plants that are blooming so delightfully. We are tempted to buy them compulsively, even if we have no immediate plans for them.

That is okay. We can make this work. Buying certain plants in bloom actually has certain advantages. It shows how and when particular plants bloom. This might be helpful when trying to decide between different cultivars of deciduous magnolias, flowering cherries, flowering crabapples or wisterias, for example. Besides, they will finish blooming quickly, and start to produce new foliage.

If planted before new foliage matures, new plants should be planted in cool weather, and maybe sprayed lightly with water after the roots get soaked in. This is best for drought tolerant plants like ceanothus, that want out of their cans (nursery pots) as soon as possible. If new plants stay in their cans long enough for foliage to mature, they must be watered carefully, but not kept saturated. The black vinyl cans should be shaded, since they get warm in sunlight.