The mental model
Watering, then, as one system. A pot runs a loop, from watered to drying to ready and back, and the dials from Lesson 5 set how fast it turns. Your whole job is to read where the plant sits on that loop and water before it runs out, not to keep a schedule. Look at the diagram, then prove you can read the signals.
Fig. 10. Watering as one system: a loop from watered, through drying, to ready, and round again. Your job is to read where the plant is on the loop and water before it runs out, not to keep a schedule.
Read the signal, name the cause
Tap a symptom on the left, then tap the explanation on the right that fits it. Diagnosis is the skill, so here you practice it rather than reading about it.
The symptom
What's actually happening
How this connects to the rest of the curriculum
Watering sits in the middle of the system, so it touches almost everything downstream:
- Module II (Reading Light) is upstream: light changes how fast a plant uses water, so "how much light is it getting?" is part of "when do I water?"
- Module IV (Substrate) is the supply side of the air-and-water balance: a mix is really a set of choices about water-holding and air-filled porosity.
- Module V (Containers) covers how pot size, height and material change the drying rate and how much of the wet band at the bottom a pot keeps.
- Module VI (Feeding) rides the watering can, and its salts are the buildup you learned to leach here.
- Modules VII and IX (Reading a Plant, Diagnosis) lean on the over-versus-under reading you just practiced.
Eight things to remember and use
- Watering is an air-and-water problem. A good watering wets the whole root zone; air comes back as the pot drains, and the drying that follows keeps the mix from staying wet.
- Overwatering and underwatering can produce the same wilt by opposite causes, so check the substrate before you reach for the can.
- After draining, a saturated band sits at the bottom of a pot with a drainage hole. The mix sets how wet each height is, and the pot's height decides how much of that wet band it keeps.
- A gravel layer is no substitute for a drainage hole. Weighed in unplanted pots, layers usually left pots holding less water, not more; we skip them because they take up room roots could use.
- Decide when to water with the finger test and the pot's weight, not a calendar.
- Water thoroughly until it runs from the drainage holes, let it drain, and empty the saucer within about an hour. Don't leave a pot standing in water.
- Frequency is a rate, set by light, temperature, humidity, airflow, pot, mix and plant size. It changes with the seasons.
- Brown tips can come from fluoride, salts, dryness or heavy feeding. For salt buildup, leach the pot with at least twice its volume of plain water; for a fluoride-sensitive plant, change the water.
Keep a one-week water log
You can read all about the wet-to-dry cycle, but your hands learn it by watching one plant go through it once. Pick a plant, and for one week check it at the same time each day. Don't change how you water; just record what you find. By the end you'll have felt the cycle, and you'll know this plant's rhythm better than a schedule could tell you.
Each day, do the finger test and lift the pot, note what you find, and whether you watered. The example row is done for you.
| Day / date | Finger test | Lift weight | Watered? (y/n) | Notes (light, room, plant) |
|---|---|---|---|---|
| ExampleMon | Moist at 1 in | Still heavy | No | East window, cool day; held off |
Finger test: note how deep it's dry (dry at surface / moist at 1 in (2.5 cm) / wet). Lift weight: heavy (recently watered) · medium · light (drying out). Water only when your finger and the weight agree it's time.
Look back at the week. How many days passed between waterings? That number is this plant, this spot, this season, and it will change when any of those do. Now you know how to tell.
"I've read this module, and I've kept a one-week water log for at least one plant."
This marks Module III complete and carries your progress forward. The work is done by your own honest account. No points, no badge, no leaderboard.