Reading the response and improving decisions

September on the west balcony, the instructional example this course has followed since spring. Like every case here, it is set in one temperate Northern Hemisphere city at about 40° N (USDA zone 7a). The afternoons have cooled from July's 30 to 33 °C (86 to 91 °F) to about 24 °C (75 °F), and the owner sits down with the summer's watering log: one short line per pot at every check, with the weather, what the checks found, and the decision.

The trident maple's lines are the first surprise. It needed water about every second day in June and every morning in July, which matched the heat. Weeks into cooler weather, it still needs water daily: the pot is light again by the next morning, and the first drips come sooner than they did in spring. Tipped back on its grid, the terracotta pot shows a mat of roots over the drainage holes, and a few roots run around just inside the rim.

The gift juniper's lines show something else. Since midsummer, a fingertip near the rim has found the coarse ring of fresh mix dry by the next afternoon after each watering, while the chopstick in the old core comes out damp and cool on its lower half days later, longest in cool spells. In October, the bright window's owner, who checks the ficus every morning, sees a third pattern in their own log: its waterings have come closer together since the heating came on.

Three records, three patterns. For each, the question is whether it calls for different watering, different checks, or nothing new. This lesson is about reading a record that way, and telling when a watering problem is really a different problem.

What to record

A watering log is a dated line for each pot at each check, in a notebook kept with the watering can or a note on your phone. What makes a line useful later is what it holds:

• When: the date and time. Checks at about the same time each day give lines you can compare.
• Weather: the day's high, the wind, and any rain, including whether it reached the pot. A min/max thermometer at pot height, out of direct sun, gives the spot's own high and low (Course 02, Lesson 5).
• Each check, in words: what the chopstick and the lift test found, in the same phrases every time, such as “Damp and cool on the lower half,” and where the chopstick went if the root ball has two zones (Lesson 2). “OK” cannot be compared with anything.
• The decision, and why: which of the three decisions you made, and the check or the weather that settled it.
• How the watering went: after a thorough watering, how soon the first drips came, whether the pot felt heavier after, and that the tray was emptied (Lesson 3).
• How the tree looks: the leaves, new shoots, and any white root tips at the holes (Course 01, Lesson 14).
• Anything that changed: a move, shade cloth, a helper's visit, root work, a trip.

A line can be as short as this: “Tue 8 am · 33 °C (91 °F) forecast, windy · Lift: lighter than after watering · Chopstick: damp and cool on the lower half · Not yet: check again this afternoon (5 pm), hot wind · Leaves firm.” Kept that short, in your own shorthand with the same words each time, it is easy to keep doing. Write a line even when nothing needs water: the “Not yet” lines show how long each pot lasts. Keep going through the winter, when the lines get fewer (Course 06, Seasonal Care and Timing).

Once a week, photograph each tree from the same spot and height, as for its arrival record (Course 02, Lesson 8). Slow changes, such as shoots a little shorter than last month, show only when dated photos sit side by side.

Seven mornings on the west balcony

A week of mornings puts the course's habit of check, decide, record to work: seven mornings of early September on the west balcony, with all three trees and a forecast card each morning. As on a real balcony, you cannot see inside the pots until the evening, so each call rests on your checks.

1. On the first morning, predict which tree will need water most often (Trident maple, Nursery juniper, or Gift juniper), or press Skip. The week's report says whether you called it.
2. Each morning, read the forecast card; on a hot or windy morning, you can switch on Add an afternoon check. For each tree, run any of the checks (Surface, Chopstick, Lift, Drainage holes, and Leaves) and read each result. A decision made on at least two checks earns a Two checks tick. Decide the gift juniper by its chopstick, which goes into the old core, as in Lesson 2. On a phone, pick the tree with Tree.
3. For each tree, choose Water thoroughly now, Not yet: check again tomorrow morning (it reads Not yet: check again this afternoon when the afternoon check is on), or Investigate before watering. The morning after a storm, press Empty the tray on the trident's card first.
4. When all three trees have a decision, press End the day. The pots open to show the root zone from morning to evening (Skip to the evening jumps ahead), and the evening card grades each call and marks any pot that went short. Press Next morning to go on.
5. After the seventh evening, press Go to your week's report, read the report and the watering log the exercise wrote, then try Replay with another week.

The three pots behaved differently all week. The trident still needed water on most mornings, even as September cooled; the junipers needed it less often, and in the gift juniper's pot the core's chopstick decided while the ring dried. More than once, a tree that looked fine was already drying and needed water now; the leaves, least of all the junipers', were never the signal to wait for. When a tree and its pot disagreed, the right call was to investigate before adding any water. A decision made on one check, or on none, got a note naming what that check could not see, and the report counted those decisions on their own.

The weather set the rest. On hot or windy days, a pot that could wait at 7 am could be drying by 4 pm: the afternoon check watered it in time, and without that check the evening card marked it Went short. The trident's droop in the late-afternoon sun came over a root zone still moist and was gone by evening: temporary wilting, which needed no water (Lesson 4). After the storm, emptying the trident's full tray came first; watering into it sent the overflow onto the balcony below. The log the exercise wrote, one line per pot each day with the weather, the checks, the decision, and the outcome, is a seven-day watering log, and the rest of this lesson reads logs like it.

Reading a log

Did each decision work?

Read each decision against the line after it. A decision worked when the next check finds the pot moist, or drying and ready for water, but not dry. A watering also needs its line to show that it wetted through: slow passes, and a pot clearly heavier after; a pot that barely gained weight means the water ran past the root ball (more below). Two other kinds of line show a miss. A chopstick dry and pale along its whole length, or a juniper gone dull and grayish, means the decision before it waited too long. A watering made on the surface alone, or over a lower half still damp, was one the pot did not need. The report in A week of mornings counted the same misses: waterings the pots did not need, times a pot went short, and decisions on one check.

Intervals, the weather, and the season

Next, read the intervals: the days between waterings, pot by pot. When each watering follows a check that found the root zone drying, the intervals show how fast that pot empties in that weather: shorter in hot, sunny, windy spells, when evaporative demand is high, and longer in cool, cloudy, still ones (Course 01, Lesson 8). So read them against the weather column: three waterings in a week means little until you know whether it was the week of the storm or the week of the hot wind.

Over a season, the intervals swing with the tree and the weather together (Lesson 1). In the example climate, they shorten through spring as new leaves open and the spring flush grows, are shortest around July, and lengthen again from September as the days shorten and the nights cool. Winter waterings are fewer, but evergreens still lose water on sunny, windy days. These months belong to the course's Northern Hemisphere example climate; in the Southern Hemisphere, swap north and south, and shift them by half a year.

Within a season, compare a week with a week of similar weather. If a pot needs water sooner than it did in similar weather a month ago, something about the tree, its pot, or its spot has changed: its roots, its foliage, its sun or shade, or the way water goes in. If it lasts much longer than it used to, its roots may be taking up less. Pots that share a place share its weather too: when the two junipers, side by side on one shelf, dry at very different rates, the difference lies in the trees, their pots, and their roots.

When the pattern is expected

Some changes in a record are the routine doing its job. At the bright window, the heating comes on in October, and the room's air turns very dry, the air rising off the radiator drier still (Course 02, Lesson 3). Air with such low relative humidity draws water from the leaves and the pot's surface faster, and the lower autumn sun reaches farther onto the sill on clear days, so the ficus dries sooner each week. Its owner already checks every morning, and every watering followed a check that found it drying. That is expected: the routine stays as it is, and the waterings come closer together.

A move into more sun or wind, a hardening-off step, a growth flush, and a heat wave shift the intervals the same way. The test is whether you can name what changed. If you can, and you already check daily, let the checks set the waterings; if you were checking less often, check daily until the log settles.

When a check is in the wrong place

Sometimes a pattern says which check should decide, not how to water. Since spring, roots from the gift juniper's old root ball have grown out into the ring of coarse fresh mix around it and draw on the ring's small store first. So the ring dries by the next afternoon, while the peat-rich core's larger store keeps it moist for days. The log shows the gap line after line: ring dry, core damp and cool on its lower half. Judged at the rim, this pot would be watered every day or two.

The chopstick in the old core, partway between trunk and rim, decides (Lesson 2; Course 02, Lesson 7), and a ring that dries ahead of a still-moist core is no reason to water. Other patterns call for other changes to the checks: a second chopstick spot when two checks keep disagreeing, an afternoon check on hot, windy days, or a better time for one (below).

A supplied week to practice on

Here is a week to read before you have a summer of your own: the west balcony's nursery juniper in the first full week of July, with two hot, windy days, a storm, and a cool day. Its black plastic nursery pot, about 20 cm (8 in) across, stands on the top tier of the slatted shelf, its sunny side shaded. The owner checks at 8 am, and again at 5 pm on hot, windy days.

Before you read on, decide each line's call, one of the three decisions or another check first, and write its reason in a few words.

The owner's calls, annotated

A strong entry: Wednesday, 5 pm. Everything a later reader needs is in one line: two checks in words, the weather that explains them, the decision, how the watering went (slow passes, water from the holes, a heavier pot), the tray, and when to look next.

No reason: Sunday. The call was right, since the lower half was still damp, but the line does not say so. A reason such as “damp on lower half, breezy, check again 5 pm” would also have set up the afternoon check. A line with no reason cannot be checked later, and a helper learns nothing from it.

One check: Saturday. The decision rested on the surface, the layer that dries first; the right call was the lift and the chopstick. After the storm and two cloudy days since Wednesday evening's watering, they would probably have found the lower half still damp: a watering the pot did not need. One extra watering of a free-draining pot in July does little harm; the habit does. In cool weather, watering whenever the surface looks dry keeps topping up a pot whose lower half never dries back, and a root zone kept wet that constantly is what overwatering means.

The other calls were sound: water on Monday morning and both hot afternoons, when the pot was light and the chopstick dry but for its tip; otherwise not yet, with an afternoon check on the hot, windy days. After the storm, emptying the tray came first, and the chopstick, not the storm-darkened surface, decided: a dense juniper canopy sheds much of the rain past its rim, a loss called interception (Lesson 5). Read down the waterings, and the intervals follow the weather: about one a day in the hot wind, then none through the storm and the cool day.

Patterns that point beyond watering

Sooner and sooner as the weather cools

Intervals that stay short, or shrink, while the weather cools run against the weather, the biggest pace-setter. First rule out a change in the spot: the lower autumn sun reaches farther under the overhang, so a pot by the back wall can get more sun in September than in July. Then add first drips that come sooner each month, a pot light again by the next morning, and roots matting at the holes or circling under the rim, and the likely cause is a pot filling with roots. Roots take up room where mix once held water, and more roots draw on what is left (Course 01, Lesson 2). A pot so full that roots circle the wall and mat at the bottom is root-bound: common and often healthy when mild, but a badly root-bound tree dries out fast (Course 02, Lesson 6).

What to do now does not change: keep checking every morning and watering thoroughly whenever the check says the root zone is drying. Have the roots assessed at the next suitable time, which for the trident means next spring (Course 11, Repotting and Root Development). A few white root tips at a hole on their own are normal, a sign of growing roots, and no reason to repot; it is the combination with the record that matters.

Water that will not soak in, or will not stay

Some logs show a wetting problem that keeps coming back: water pools on the surface at every watering and takes a long while to reach the holes; or the first drips come within seconds and the pot barely gains weight, a sign of channeling; or the root ball will not rewet after slow passes and immersion watering. The first time, treat it as technique (Lesson 3): slow passes, immersion for a dry or water-repellent root ball, and a chopstick to confirm. If a peat-rich root ball turns water-repellent again each time it dries out, change the routine next: check it more often, with an afternoon check on hot days, so it gets water while it is drying, before it is dry all the way down. If water still pools or channels after all that, the substrate itself is the likely cause: a mix that has broken down or packed tight, or one that sheds water even when it has not dried out. Course 04, Soil, Substrates, and the Root Environment, explains why, and replacing a mix is part of repotting (Course 11).

Tell this apart from a root-filled pot by the weight. A thorough watering still leaves a pot full of roots heavier, with the chopstick damp; water that channels past a dry core leaves the pot barely heavier and the core dry.

A pot that stays wet in warm weather

In warm weather, a free-draining pot with working roots and a tree in leaf dries within days. When the log shows a pot heavy and the chopstick wet along its whole length day after warm day, something is keeping the water in: blocked holes, water standing underneath, a mix that holds too much (Course 04), or roots that have stopped taking water up. The root zone stays saturated, and roots short of air take up less, so it dries more slowly still. Changing the watering alone will not fix this. Investigate before watering (Lesson 4): add no water, check the holes and underneath the pot, smell the mix, and think back over recent root work, moves, and standing water. If the tree droops, dulls, or yellows as well, get help (Course 07, Tree Health and Diagnosis).

Keep the season in mind: even a sound pot dries slowly in cool weather, in shade, or while a deciduous tree is bare (Course 01, Lesson 7). A bare trident that stays heavy for days in November is not this pattern.

Decline despite a sound record

Sometimes the record is good: two checks every morning, waterings only when the root zone was drying, each one confirmed, trays emptied, no long wet or dry spells. Yet over weeks and months the tree does worse than the season explains: shoots stall, new leaves come out smaller or paler, foliage thins, or tips die back. That is decline. A sound record makes recent watering an unlikely cause. Read further back in the log for an earlier dry or wet spell, because old root damage can surface weeks or months later (Course 01, Lesson 14). Then look beyond the moisture: light, pests, root disease, soluble salts, or what is in the water itself (Lesson 5). Finding the cause belongs to Course 07, and the log is the first thing anyone helping will want to see.

Five records to read

Read the record gives you five short watering logs from the course's cases. Each is a table of checks, decisions, and notes, beside a strip chart of the days between waterings and a picture of the pot, cut away to show the root zone.

1. Choose a record, A to E. Before you mark anything, read its strip chart against the weather in its rows, and ask whether the intervals follow it. Press Previous and Next under the picture to see what each row's checks found inside the pot and, where the notes give it, when the first drips came.
2. Press Mark this row on every row that shows the record's pattern. On a phone, each row is a card, and Choose your conclusion at the end of the log takes you to the answers.
3. Under Your conclusion, choose what your marked rows support: Expected: keep the routine, Adjust the checks, Look into the substrate (Course 04), Investigate the tree's health (Course 07), or Have the roots assessed (Course 11). Each conclusion fits exactly one record.
4. Press File this record. A record is filed only when the conclusion is right and at least one of your marked rows shows its pattern, and the feedback tells you how many of the rows that show it you found. After a miss, change your marks or your conclusion and file it again.
5. File all five, then press See the summary. If two records seem to fit one conclusion, reread the rows you marked in both.

In every record, the pattern showed in three rows, not one. The balcony trident's waterings stayed daily into a cooler September. Its first drips came sooner each month, although every watering still wetted the pot through, and roots matted at the holes: a pot that may be filling with roots, to be assessed next spring while the morning check carries on. The gift juniper's ring dried by the next afternoon while its old core stayed damp, and each watering had been decided at the rim, so the checks change: the chopstick in the core decides, not the fingertip at the rim. The ficus dried sooner each week as the heating came on, and its daily check was already catching it: expected, so the routine stays. A pot that stayed wet all the way down for five hot, dry days in early July, with nothing standing under it, while its new leaves yellowed, was a question about the roots and the tree's health. A pot whose water pooled on the surface and took a long while to reach the holes at every watering, even with slow passes and after an immersion the week before, was a question about the substrate. In each, the record named where to look next, not what was wrong.

What a log cannot tell you

A log records what happened together, not why. If a pot moves to a sunnier spot in the week a heat wave arrives and dries faster, the log cannot say which did it. So change one thing at a time, and judge it against a week of comparable weather. For the same reason, a record sends you to look somewhere, not to a verdict: roots matting at the holes make a full pot likely, not certain.

One odd day is not a pattern. A pot that dried by noon on one gusty day shows the weather, not the pot. Wait until the same thing shows in several lines in comparable weather before you change the routine.

Nor is an interval a forecast. One learned in July would water far too often in a cool, wet week, and one learned in a cool week would leave the same pot dry in a heat wave. The log tells you when to look closely; the check decides each watering.

Improving decisions

A log does more than catch problems: read week by week, it makes every check a little better.

Predict, then check, then compare. Before each check, guess what you will find from yesterday's weather and the last few lines, then check. The mornings the guess is wrong show what you have not yet learned about a pot, so note them. The guess never replaces the check; it is how the check teaches you.

Move a check, or add one. Look at what the later checks find. If the 5 pm check on hot days keeps finding a pot dry and pale along the chopstick's whole length, the pot has already gone short, and that check comes too late: move it to mid-afternoon, so it finds the pot drying rather than dry (Lesson 5). In the supplied week, both 5 pm checks found the nursery juniper drying, light with the chopstick dry but for its tip, so 5 pm was on time for that pot. Keep the morning check at the same time, so its lines stay comparable.

Hand the log to your helper. Your log shows what normal looks like: which pot dries first, how long each lasts in hot and in cool weather, and where the chopstick goes in the gift juniper's pot. Copy that onto the helper's card (Lesson 6), and ask for one line per pot at each visit, so the record has no gap.

Review the log once a week

This lesson completes Watering and Daily Observation: checks below the surface in place of a schedule, waterings that wet the whole root ball and drain, hard cases told apart from simple thirst, a routine that holds up through busy weeks and time away, and a record that shows whether it all worked. Quiz 2 brings the whole course together in a final case. After it, Course 04, Soil, Substrates, and the Root Environment, now being prepared, will explain why pots dry the way they do.