Containers, equipment, and a workable space

The gift juniper, this course's instructional example of a tree that is already home, came from a supermarket in mid-December. Lesson 3 planned its move off the warm windowsill, to a cool, bright, frost-free place and later the west balcony. First, look at what it is growing in.

The pot is a wide, shallow oval with a glossy cobalt-blue glaze and small feet. Tilt it, and the base is solid: there is no drainage hole. The surface is a crust of pebbles glued together, so you cannot see the mix, push a fingertip into it, or watch water soak in. The tag says “Water twice a week.” The tree is green and firm.

The same shop also sold tool kits, humidity trays, moisture meters, and special soils. So the owner has two questions: what does this tree need from its container and setup this week, and what can wait?

What a container has to do

Whatever it looks like, a container has three jobs to do for the roots: let extra water out, let air back into the substrate, and let you see and reach the surface. The place where it stands has jobs too, which come later in this lesson.

A way out for extra water

After a thorough watering, the substrate holds what it can in thin films around its particles and in its smallest pores. Gravity pulls the rest down, and a drainage hole lets it leave; without one, every watering adds to the water already in the bottom. The hole also needs somewhere to drain to. A pot standing flat on a tray or smooth concrete drains slowly, while feet, a slatted shelf, or a grid let water drip clear.

Large holes are covered on the inside with drainage mesh, a small square of plastic or metal screen that keeps the substrate in while water runs out. Three kinds of container drain well:

• Nursery pots, the plain plastic pots most garden-center trees grow in.
• A training pot, a plain, inexpensive container, usually plastic, used while a tree grows and develops rather than for display. Roomier than a bonsai pot, it is the practical next home for a tree whose pot will not drain.
• A bonsai pot, a shallow container, usually ceramic, with large drainage holes, small holes for the wire that ties a tree in, and feet. Moving a tree into one usually means reducing its roots to fit, so it comes later (Course 11, Repotting and Root Development, and Course 16, Pots, Composition, and Display). The gift juniper's glazed pot looks like one, but a bonsai pot always has drainage holes.

Air back in the pores

Draining matters because of what comes in behind the water. As the extra water drains, air is drawn into the larger pore spaces (Course 01, Lesson 2), and roots need that air: their living cells respire constantly, using oxygen (Course 01, Lesson 7). This supply is called aeration.

In a pot that drains, the substrate is saturated, every pore full of water, only briefly after each watering. In a pot that cannot drain, the bottom stays saturated. Within hours to a day or so, sooner in warm weather, the roots there run short of oxygen, a state called hypoxia, and if it goes on, their tips die back while the foliage still looks fine. A juniper, a conifer whose needles lose water slowly, can stay green for weeks while its roots fail (Course 01, Lesson 14).

Winter slows the harm, because cool roots use oxygen more slowly, but a cool pot also dries more slowly, so its wet bottom stays wet longer. And a glazed pot full of water can crack in a hard freeze.

A surface you can see and reach

The surface is where water goes in and where you check what is happening below. Water should soak in across all of it, and you need to see and touch it: to push in a chopstick and to spot weeds, pests, or roots.

Many mass-market trees arrive with pebbles glued over the surface to hold the tree and its mix in place while they are shipped and sold (Lesson 6). The glue sets into a crust that sheds water and hides the mix. That mix is often rich in peat, which shrinks as it dries and then repels water for a while, so a drying root ball can pull away from the pot wall and leave a gap where water slips past.

Watch where the water goes

In Where does the water go?, the same small juniper grows in the same mix in four containers: Draining pot on a slatted shelf (A), Nursery pot in a cover pot (B), Glazed pot, no hole (C), and Glued stone crust (D). B stands inside a cachepot, or cover pot: a decorative outer pot with no hole. On a phone, pick a container with Container.

1. Press Water, then Water again for the 2nd and 3rd waterings, a few days apart, and read the status under each drawing. What builds up, and where? Back, Next, and Pause hold a moment for a closer look.
2. Under Choose a correction, pick a fix for B, C, and D. When you find the proportionate one, press Water to test the fix.

Only A behaved the same way at every watering: water ran through and out, and by the next day air was back in the pores, with a thin wet layer at the very bottom (Course 04, Soil, Substrates, and the Root Environment, explains why every pot keeps one). B drained like A, but into a pool that deepened with each watering. In C, the saturated zone rose every time while the surface dried and looked ready for more. In D, water ran out of the holes every time, yet the core grew drier. None of them looked wrong from above.

Each proportionate correction changed only what blocked the water, the air, or your view. The gift juniper has both C's problem and D's, and together they hide each other: water that runs off its crust collects in a pot that cannot drain, so the root ball can be dry in the middle and waterlogged at the bottom, with no surface to check.

Three problems, three proportionate fixes

A proportionate correction is the smallest change that solves the problem. The biggest change, repotting with root work, costs the tree the most: loosening or cutting roots destroys many of the fine roots and root hairs that do most of the absorbing (Course 01, Lesson 2). None of these three problems needs it.

A cover pot that holds water

Gift plants are often sold as a plain nursery pot dropped into a decorative one, and the foil sleeve around many supermarket plants does the same job. The inner pot drains; the trouble is where the water ends up. So water at the sink and let the inner pot drain before it goes back, or tip out the cover pot once the dripping stops, and tear a foil sleeve open at the bottom. A spacer such as pot feet keeps the inner pot above a little water, but the cover pot still needs emptying. Outdoors, rain fills a cover pot too, so take it off or check it after every rain.

A pot with no drainage hole

No watering routine makes up for a missing hole (Course 01, Lesson 7). Watering less leaves the top dry while the bottom stays wet, and small sips still collect out of sight; following the tag's “Water twice a week” is exactly how water builds up unseen. Drilling the glazed base is possible with the right bit, but the tree has to come out first anyway, and the glaze can crack.

The proportionate fix is slip-potting: moving the root ball, whole, into a slightly larger pot that drains, and filling only the gap around it with fresh, free-draining substrate. The roots are not loosened, washed, or cut, so the tree has almost nothing to recover from, and the job does not have to wait for the repotting season. For the gift juniper in December, it is the right move now.

1. Choose the pot. A plastic training pot with drainage mesh over its holes, a finger's width or two wider than the root ball all round and a little deeper. Bigger is not kinder: mix the roots cannot reach yet stays wet for a long time.
2. Ease the root ball out. Over a sink, turn the old pot on its side, spread one hand across the surface on either side of the trunk, and let the root ball slide out whole. Never pull on the trunk.
3. Set it at the same height, on a thin layer of fresh mix, so its top sits where it did before, a little below the rim.
4. Fill the gap with fresh mix, working it down gently at the edge with a chopstick until the tree sits steady. If it still rocks, ask an experienced grower to show you how to tie it in (Course 11 covers anchorage after repotting).

Glued stones over the surface

The crust has to come off, but the pebbles can be glued to the bark at the base of the trunk and to roots that have grown into the glue, so prying the crust off in one piece pulls on the trunk and tears roots.

Soften it first. Once the tree is in a pot that drains, stand the pot in a basin of water that comes up to the crust until the glue softens; some glues soften within an hour or two, others barely at all. Take the pot out after a few hours at most, softened or not, because roots left standing in water run short of air. Lift the stones away in small pieces, from the edge toward the trunk, then let the pot drain fully. The soak also wets the dry core through and settles the fresh mix. If the crust will not soften, chip it away from the edge a piece at a time, and leave any stone stuck fast to bark or a root for later.

Doing the pot first and the crust second lets the soaking water drain away instead of adding to the water trapped in the old pot.

A workable space

A container also stands somewhere, and that place has to be safe and make daily checks easy: a tree you can see and reach is a tree you check.

Stable, secure, and easy to reach

On the fourth-floor west balcony, wind is strongest at the open south end, and a small tree in a light plastic pot is top-heavy. Give it a sturdy slatted shelf that cannot tip: broad and heavy enough to stay put, or fixed in place where building rules allow (Lesson 1). Tie a light pot to it with soft cord through the slats. Set the shelf just inside the railing, with its top no higher than the top rail, and never stand a pot on the railing itself, so that nothing can tip over the edge onto the balconies and people below.

At bench height, about 80 cm (about 2.5 ft) or a little higher, you can see the foliage, check the surface, and water without stooping, and a slatted top keeps the pot draining and off concrete that gets very hot on summer afternoons (Lesson 5). For a sun-loving juniper on this balcony, the best place for that shelf is at railing height in the open middle, set just inside the railing, in the afternoon sun: it beats the dim back wall under the overhang and the spot beside the condenser in the north corner. On winter nights, though, that open shelf is also the coldest spot (Lesson 5), so a pot there needs its roots protected from hard freezes (Course 06, Seasonal Care and Timing). The cases are in the Northern Hemisphere, where the midday sun is to the south; in the Southern Hemisphere, swap north and south.

Water you can carry, and runoff you can catch

The balcony has no outdoor tap, so every watering is carried from the kitchen, in a can small enough to carry when full. On its spout, a fine watering rose, a cap pierced with many small holes, breaks the flow into a gentle shower that wets the whole surface evenly without washing out the mix or cutting a channel through it. Course 03, Watering and Daily Observation, covers technique.

Water that drips off this balcony lands on the neighbors' balcony below, and many buildings have rules about it. Pour slowly, stop once water runs from the holes, and catch it in a shallow tray under the shelf, or under the pot with a grid that keeps the pot above the water. Empty the tray after every watering so that it never becomes a cover pot. While the gift juniper is still indoors, water it at the sink instead.

Simple tools for observing

The first tools to own are for watching the tree, and most are cheap or already at home:

• A notebook or phone camera for dated notes and photos from the same angles (Lesson 8 shows what to record).
• A min/max thermometer at pot height, out of direct sun, to learn what the spot really does on frosty nights and hot afternoons (Lesson 5).
• A plain wooden chopstick, pushed into the root zone for a few minutes, which comes out darker and cool where the mix is moist (Course 01, Lesson 2). With the weight of the pot, it tells you far more than the surface.
• A hand lens, about 10×, for checking a new arrival for pests (Lesson 8); a zoomed-in phone camera can stand in.

Cheap probe moisture meters respond to soluble salts in the water and to how well the probe touches the particles, not only to the water itself, so in coarse mixes their readings are often unreliable.

What to buy now, and what can wait

Buy now, later, or skip for now? asks you to sort 14 items for one stated case: the gift juniper, heading for the west balcony in December. Read the case panel, then for each card choose Now, Later, or Skip for now and read why. Your kit so far fills as you go; once all 14 are sorted, Kit sorted shows the pattern, and Worth another look: links back to any card that differs from the stated answer.

The seven Now items all came up earlier in this lesson: a training pot with drainage mesh and a small bag of free-draining substrate for slip-potting, a can with a fine rose, a stable shelf, a min/max thermometer, a chopstick, and a notebook or phone. Most are cheap or already at home, and the pot is the most urgent. Scissors, a concave cutter, and wire wait for the courses that teach their use (Course 09, Pruning and Managing Growth, and Course 10, Wiring and First Styling). The tool kit, humidity tray, probe meter, and grow light add little for this tree. Only the grow light carried a note that it depends on the tree, but every answer depends on the case: change the tree, the place, or the season, and some items move.

The gift juniper's first setup