maintenance customers, we also do a lot of supply only contracts too. Last week we put eighteen planters in a private house north of Bournemouth. All the indoor planters we sell are waterproof, so watering takes more skill than one with drainage holes in, as any excess doesn't just fall out.
So the question we always get asked, and have to do our best to answer is, "How much should I water it?".
The problem is, the answer isn't a simple one, but most people want a simple one, so for example my reply will be "You need to feel the soil every time, but I would imagine it'll drink up to half a watering can in a fortnight in good weather".
What the client hears is "Blah blah blah half a can a fortnight blah blah". They will then proceed to put half a can on religiously each fortnight until the plant drowns. So here's as simple a guide to watering as I can:
1. Always test the soil first
It doesn't matter how well you know the plant, always, always scrape a little of any stone top-dressing there may be on the compost away, then stick a finger in the soil to see how wet it is. If you are a lady (or man!) with nicely manicured nails, use a knuckle. But always do this, then if it feels wet, don't water it!
2. Water at regular intervals
We water most of our maintenance contracts fortnightly, and this suits most plants. But most importantly, this routine means the plant is likely to get consistent water delivery. A tip to remembering this is to make "plant watering day" the same as another fixed point in your diary, e.g. the day you put the bins out.
3. Don't take too much notice of plant books, the plant's label or what people tell you about how thirsty your plant is
All of my very experienced staff will tell you they have numerous plants that don't behave how they should. I have a row of (usually dry loving) Mother-in-Law's Tongues at a contract in Swindon that drink like fish. A colleague used to have a big Ficus in a sunny porch (should need at least a can a week) that drank virtually nothing. See rule 1. If it's wet don't water it, if it's dry, do. Knowledge of plant species is a useful predictor of how much they will drink and a guide to how much to put on a dry one, but it does not trump testing and experience. If you have a plant that seems to want to drink more/less than knowledge tells you it should, let it!
4. Learn from your mistakes
You will probably find that your watering style oscillates a bit from too wet to too dry. Everyone's does this - I've been doing this professionally for fifteen years and mine does. If you ever dig an old plant out, take note of how wet the deep soil is, this can be a useful guide to whether you're getting it right.
5. If looking after other people's plants, try and copy their watering.
This might sound silly, but if you look after someone else's plants for them you have to do it the same way (even if they are doing it wrong!) or the plants will suffer. The explanation is complicated and involves different types of root growth, but trust me, it's true.