Dividing and Transplanting: An Example Project and Beginner’s Guide

The best time of year to move some plants is summer. Plants that bloom in the spring and have fat, sturdy roots are candidates for summer transplanting. Irises are the most commonly mentioned group, but I have found that various Solomon’s seals also respond well to summer moves—actually any time after the flowers have dropped.

I looked at my dwarf Japanese Solomon’s seal the other day, and realized that it was really muscling in on my liverworts. There are only four liverworts, and about a gazillion dwarf Japanese Solomon’s seal, so the solution was to recreate the gap between them by digging up and moving some of the Solomon’s seal. This divide-and-transplant project will show you how to plan and implement a transplanting project with smallish plants—a very good place to start.

These instructions are based on some assumptions.

  • There has been enough recent rain for the soil to be hydrated but not soggy. About the only time you should not attempt transplanting is during extreme weather: wet or dry spells, or heat waves. Cold is OK, as long as there isn’t an unseasonable freeze predicted.
  • You are working with real soil, and not recent builder’s backfill or a hardpan left under a couple of inches of applied topsoil and lawn.
  • The area that you are moving the plants to has not had an herbicide applied in a year. Six months is pushing it, especially if those months were winter.
  • You have someone watching your small children; the plants will need your full attention for at least a little while.

This is how transplanting generally goes. Details will follow.

  1. Check the weather forecast.
  2. Look over the candidate plants to see what needs to be moved.
  3. Find a new spot for those plants.
  4. Check soil moisture.
  5. Have a container of water nearby to dunk the roots in, and another container to put the plants in for their move.
  6. Do a test dig.
  7. Dig the plants.
  8. Divide the plants.
  9. Map out the new spot.
  10. Dig holes, plant, and fill.
  11. Monitor for water.
  12. Monitor for disturbance.

Check the weather forecast.

Goal: Reduce transplant shock and your future workload.

Look for rainy days, or at least cloudy calm days, in the forecast to make the transition easier for your transplants. If it doesn’t rain, you may have to water every few days. Plan on doing the work during the cooler part of the day—morning or evening. It’s better for you, and better for the plants.

Look over the candidate plants to see what needs to be moved.

Goal: Move plants that are not quite fitting in where they are.

Look for plants that are

  • too tall or too short for their current spot
  • too similar to their neighbors
  • clashing visually with their neighbors
  • getting too much or too little water or sun
  • getting overrun or expanding beyond their edge.

In this case, the Solomon’s seal had grown so close to the liverwort that the liverwort’s leaves were pressed up against them—like passengers on a crowded subway.

Find a new spot for those plants.

Goal: Solve another problem beyond the one the transplant candidates are having.

This is a chance to smooth out a rough edge, start a new bed, or expand a planting. Look for the right mix of sun, shade, and dampness.

Check soil moisture.

Goal: Make sure that the soil is damp enough to release the plants, but not so wet that it will turn into an air-free slick if you start messing around with it.

Grab a handful of soil. Squeeze it.

  • If it didn’t stick together, stop right there. It’s probably too dry.
  • If it stuck together, poke it.
    • If you just made a wet hole, stop. The soil is probably too wet.
    • If it falls apart, great! Keep going.

Have a container of water nearby to dunk the roots in, and a holding container to put the plants in for their move.

Goal: Make sure the plants do not dry out before you are done planting them.

They will just need a dunk—there’s no need to soak them. The goal is a film of water on the roots. A plant saucer, a bowl, or a small bucket with a couple of inches of water in it will do.

The moving container needs to be moveable once you have loaded it—that seems really obvious, but the triumph of finding the perfectly sized container can blow that little moving detail clear out of a person’s head.

Do a test dig.

Goal: Make sure you know how deep to dig to get all the roots.

Trowel, left, and poaching spade, right. The silver section of the spade always gets below the dirt, but if you look carefully at the section that bumps out over the handle, you can see it’s also worn almost all the way to the top of the blade; that section is frequently but not always buried. Photographed July 16, 2017.

Use a poaching spade, not a regular spade, trowel, or shovel. A regular spade is generally too big. Trowels are too small. Shovels are built to go into the soil at an angle and will cut off the roots that you are trying to dig up.

An idealized soil plug, showing a generalized plant and the relation of spade to plant. A lot of soil will fall off when you leverage this soil plug out. Drawing ©2017, P. G. Martz; created in Affinity Designer.

Your first task is to cut a plant plug containing a plant or clump of small plants, and the roots and soil they are in. The walls of your plant plug should be near the dripline of the plant and most of the depth of your spade. Drive the spade straight down all the way around your transplant candidate.

Examine the area at the soil line as you go so that you can identify it and replant to the same depth.

An established dwarf Solomon’s seal with the soil line just showing. Photographed July 16, 2017.

Go back to the side where it will be easiest for you to lever the handle down. Sink the spade into the cut you already made.

Working carefully, start levering the handle down, but be aware of the tension on the shovel handle. If you start feeling a lot of roots snapping, slow down. Move the spade around your plant cylinder, levering to get the bottom of the cylinder to release. It will probably not look neat when you pull it out. Don’t worry about that.

Once you get the plant (or clump) out, shake or tease the soil off—right back into the hole you just made—and look at the roots. Do you have a good clump of roots? In the case of Solomon’s seal, a whole loosely interwoven clump will come up when you dig. Once you shake and tease them apart, the roots are not actually very long, but you cannot get those little roots out intact by digging with a trowel. I’ve tried.

A single dwarf Japanese Solomon’s seal plant. This one has a very nice collection of feeder roots. Photographed July 15, 2017.

Dig the plants.

Goal: Dig up what you can re-plant in one session.

Dig up your transplant candidates using what you learned from your test dig. If at all possible, dig up only what you are sure you can re-plant in one session. The rest are safer in the ground than in a holding container.

Put your plants, standing up right next to each other, if possible, in whatever holding container you have chosen: a big plant saucer, bucket, wheelbarrow, box, or even a tarp. Keeping them close together like this will reduce drying. Keep them out of the sun, or throw damp newspaper over them.

Separate the plants.

Goal: Prepare the plants for their move.

Take them out of your holding container. Gently shake the dirt off each plant or clump; divide as needed. Dunk their roots in the container of water that you put aside earlier, and put the plants back in the holding container standing up next to each other. Keep them in the shade, or shaded.

Map out the new spot.

Goal: Have a plan for spacing out your plants.

Lay out some of the prepared plants in the new spot to see how you are going to arrange them, then put them all back together in a huddle to keep them from drying out. Dwarf Japanese Solomon’s seal is small and needs small planting holes that can be made with a trowel, so I worked with 10 or 12 plants at a time.

Bare-root dwarf Japanese Solomon’s seal, in a huddle, awaiting planting. These were a small part of a single clump that was shaken and teased apart, gently. The roots are healthy and plump; each plant has at least two fat roots and a lot of little feeder roots. Photographed July 15, 2017.

Dig holes, plant, and fill.

Goal: Make sure each plant’s roots are resting firmly on soil, not hanging out to dry in air pockets.

Dig a hole to match the shape of the roots of a specific plant and plant it immediately. Sometime you really don’t need much more than a slot.

Dwarf Japanese Solomon’s seal standing in its hole. Each of those root tips will eventually send up a new plant. Photographed July 15, 2017.

Audition the plant in its hole before filling it in. Do the roots touch the soil all the way around? Is it at the right depth? You may have to put a tiny little hill of soil under some of your transplants’ roots to ensure good soil contact. Fill the hole with the soil you removed from it. Pat the soil down firmly, but not too firmly. You want to ensure contact, but not squash all the air out of the soil or break the roots.

Do not add stuff to the soil—don’t “improve” it. Amending the soil and making a hole twice the width of the roots has been recommended for decades, but people are beginning to realize that a plant in a cushy blob of soil contained in otherwise bad soil functions like a potted plant. It’s OK for a while, but as the cushy, improved soil fills with roots, the plant becomes susceptible to drought.

How deep do you plant the plant? Plant it as deep as it was before you dug it up. Standard advice, but not very helpful; you need a better clue. Is it where the blush of the stem fades to white? After carefully moving the soil away from several stems, I realized that this particular plant has a built-in soil line! The soil line will be just showing when the hole is filled. Some light permeates the top of the soil, so the stem shows color about ¼ inch below the soil line.

Dwarf Japanese Solomon’s seal. The yellow arrow points to the handy built-in soil line. The root that is running out to the left is already turning upward to form a new stem. Photographed July 15, 2017.

Water gently after transplanting to settle the soil in well around the roots. All roots need some air, but big air pockets will cause them to dry out and die. Water will help move soil particles among fibrous roots.

Monitor for water.

Goal: Make sure the transplants don’t reach their permanent wilting point.

There is no coming back from the permanent wilting point. Check transplants morning and evening; they may not survive 24 hours of drooping badly. Plants with thinner leaves need to be monitored closely for water needs, and perhaps pruned back to reduce the leaf area, which is where plants lose most of their water.

Irises and Solomon’s seal should remain perky, but other thinner-leaved plants may droop a little. If you see drooping, check the soil near them, but outside the potential root zone, with a trowel: stick it straight down into the soil, and pull towards you. If it looks dry more than an inch below the surface, water your transplants thoroughly—at least an inch of water. They should not need water more often than every 3–5 days, assuming that you have middling soil—neither very sandy nor very heavy clay.

Monitor for disturbance.

Goal: Make sure that plant roots do not remain exposed to dry out.

Squirrels, the inspectors general of all yard work, may decide to check your work. You may have planted something tasty in their yard, and they call dibs. Forever. Secondly, as a mere human, any digging you do may need correcting. Check their checking, and pat the soil back down around anything that’s been disturbed.

A newly extended bed of dwarf Japanese Solomon’s seal. The area below the dotted yellow line is almost all new transplants. You can see there has been some poking around in the bottom righthand corner. Fortunately, these plants are just not that interesting to rodents. Photographed July 16, 2017.

Transplanting Other Plants

Some plants are fussy about when and how you transplant them, while others are much  more resilient. The ideal time to move plants revolves around dormancy: either move them before they break dormancy, just as they break dormancy, or after they go into dormancy. If you don’t have much experience, start with easy plants.

Some resilient plants and their moving times.

Spring bulbs can be moved once the foliage has yellowed, as they have made all the food that they will for the year, and you can still find them without guessing where they may be. Daffodils are a great starter bulb, as they are somewhat forgiving about depth. Some bulbs, such as  grape hyacinths, send foliage up in late summer for the following year. They will not bloom well the following spring if you move them once the foliage comes up.

Any iris can be transplanted after it blooms, in the summer; salvia or bee balm can be divided and moved in the fall. Daylilies are extremely resilient, but their roots will put up stiff resistance to being dug up or divided.

Finally…

Plants get heavy faster than anyone thinks. A cubic yard of soil weighs roughly 2200 pounds, depending on how wet it is, so a cubic foot (that’s a cube that is 1´ wide by 1´ long by 1´ high) is roughly 82  pounds. That doesn’t include the weight of the plant! Remember that you are not just lifting it, you are also forcing it to let go of its current spot. Take care of your back and get help for big moves, or reconsider moving the plant.