Calathea and Prayer Plant Care: Why Yours Has Crispy Edges

Calathea and maranta get recommended for beginners because they tolerate low light. That is true and it is also misleading, because low light tolerance is not the same as being easy.

They are difficult for two specific and fixable reasons: they are sensitive to what is in your tap water, and they need more humidity than a heated house provides. Solve those and most of the drama stops.

Water quality, which is the one nobody mentions

These plants are unusually sensitive to fluoride, chlorine and dissolved minerals. They cannot excrete them, so the compounds accumulate at the leaf edges and tips and kill the tissue there. That is the crispy brown margin everyone has.

Use filtered, distilled or rain water. This single change fixes more calathea problems than anything else, and people spend months adjusting humidity instead.

Standing tap water out overnight allows chlorine to evaporate, which helps a little. It does nothing for fluoride or hard water minerals, which do not evaporate. That advice is repeated constantly and it is only half true.

Humidity

They want 50 to 60 percent and up. A centrally heated house in winter often runs at 20 to 30, which is desert territory for a rainforest floor plant.

What works: grouping plants together, a tray of damp pebbles with the pot sitting clear of the water, a small humidifier in the room, or a bright bathroom.

What does not work: misting. It raises humidity for a few minutes and leaves water sitting on the leaves overnight, which encourages the fungal spotting these plants are already prone to.

Water, light and warmth

Water when the top centimetre or so is dry. They want consistently lightly moist soil, never soggy and never bone dry. Both extremes cause damage that shows within days.

Light should be medium to bright indirect. They grow on forest floors under canopy, so direct sun bleaches the patterning that is the whole reason to own one. Too dark and the colours dull and the plant stops growing.

Warmth matters more than people think. They dislike anything below about 16°C and hate cold draughts. A calathea against a cold windowpane in January will not recover.

Reading the symptoms

1. Crispy brown edges all round the leaf. Water quality first, humidity second.Switch water
2. Leaves curled inward and staying curled during the day. Underwatering or very low humidity.Water and humidity
3. Leaves folded up at night and open by morning. Normal. It is called nyctinasty and it is where the name prayer plant comes from.Nothing wrong
4. Yellowing lower leaves, soil damp. Overwatering.Ease off
5. Faded washed out patterning. Too much direct light.Move it back
6. Fine pale speckling and webbing. Spider mites, which love these plants in dry winter air.Treat weekly, three cycles
7. One or two old outer leaves dying off slowly while new ones emerge. Normal turnover.Fine

Calathea, maranta, stromanthe, ctenanthe

All in the same family, all pray at night, all want the same care. The differences are cosmetic.

Maranta grows more horizontally and trails, with rounded leaves and often red veins. The most forgiving of the group.

Calathea grows more upright in a clump, with the boldest patterning.

Stromanthe usually has pink or deep red undersides and needs the most humidity.

Ctenanthe is bushier with longer narrower leaves.

If you want the look and less of the difficulty, start with a maranta.

Repotting and feeding

Repot every couple of years in spring, one size up. They like a snug pot and dislike disturbance, so do not do it more often than needed.

Use a mix that holds moisture without waterlogging: ordinary compost with perlite and a little coir or bark.

Feed at half strength monthly in spring and summer, nothing in winter. They are sensitive to salt buildup, so flush the pot at a sink every few months.

Worth knowing

Calathea, maranta, stromanthe and ctenanthe are all non toxic to cats and dogs, which makes them one of the few genuinely pet safe options with dramatic foliage.

And accept some damage. These plants have thin leaves and any lapse leaves a permanent mark. Trim the crisp edges just inside the brown following the leaf shape, and judge your changes by whether new leaves come in clean rather than by whether the old ones recover.

The species matters here, since stromanthe wants noticeably more humidity than maranta. Photograph a leaf with the underside visible and Identium will tell you which of the four you have.