Which is better, using a moisture meter or going by the weight of the pot?

[SakuraDrops]

How accurate are moisture meters?
Sometimes I feel unsure about watering my cattleyas. Is there a way to be 100% sure? Or is going by the weight of the pot the best way?

[Roberta]

Moisture meters are useless in orchid media. They are designed for soil, not medium full of air spaces. Go by weight... weigh on a postal scale or kitchen scale right after you water, and again in subsequent days. When the rate of water loss slows down (not much more water to evaporate) then water again. If the medium is free-draining (and for Catts it should be... medium to large bark depending on pot size, or lava rack) then you really can't over-water. Epiphytic orchids want "humid air" in the root zone, not "wet". If the medium is free-draining, plants will dry fast and when you water well (running through the pot) you pull fresh air into the root zone.

[estación seca]

Agree. And realize many orchids do not want to be dry between waterings during the growing season. These prefer staying always moist. Pay more attention to plenty of air at the roots.

[Ray]

Another option - and one I prefer - is to use potting media whose pores cannot be filled with liquid when you water. Coarse enough and with the proper choice of materials and you can water until the cows come home with no issue.

[SakuraDrops]

Originally Posted by Ray

Another option - and one I prefer - is to use potting media whose pores cannot be filled with liquid when you water. Coarse enough and with the proper choice of materials and you can water until the cows come home with no issue.

Thank you Ray. Would you mind giving some examples of the type of medium you are describing? I don't know anything about pores in medium, it is my first time hearing about this.

[estación seca]

He means the spaces between pieces of the medium. Imagine a plant container filled with golf balls. There are large air spaces between the golf balls. Now imagine a plant container filled with fine sand. The spaces between particles are very small. If you pour water through the golf balls, their surfaces remain wet, but there are still large air spaces. If you pour water through the fine sand, enough water may be retained between particles that there is no air remaining.

Air is the most important thing for epiphytic orchid roots. Most orchidists grow epiphytes - plants that grow on tree branches with roots exposed. So when potting them the size of individual pieces of medium matters a lot.

Bark is sold in different sized particles. Cattleyas and Phalaenopsis do well in medium to large bark. The larger the bark the more often you will need to water. People in very wet places choose very large bark. If you want to water less often you can choose smaller bark.

Some orchids never want to dry completely when in growth. For these, smaller particle sizes work better. This includes most Dendrobiums, Oncidiums and their intergeneric hybrids, Paphiopedilums and Phragmipediums.

Potting media used can be any of these alone or in combination: Bark, volcanic cinders or scoria, clay balls for horticulture called LECA, horticultural charcoal, perlite, pumice. Many of these are sold in different sized particles. They all have various advantages and disadvantages.

Sphagnum moss also works well as a potting medium for most orchids, but watering plants in sphagnum is very different from watering in particulate media, so that is a different topic.

[SakuraDrops]

Originally Posted by estación seca

He means the spaces between pieces of the medium. Imagine a plant container filled with golf balls. There are large air spaces between the golf balls. Now imagine a plant container filled with fine sand. The spaces between particles are very small. If you pour water through the golf balls, their surfaces remain wet, but there are still large air spaces. If you pour water through the fine sand, enough water may be retained between particles that there is no air remaining.

Air is the most important thing for epiphytic orchid roots. Most orchidists grow epiphytes - plants that grow on tree branches with roots exposed. So when potting them the size of individual pieces of medium matters a lot.

Bark is sold in different sized particles. Cattleyas and Phalaenopsis do well in medium to large bark. The larger the bark the more often you will need to water. People in very wet places choose very large bark. If you want to water less often you can choose smaller bark.

Some orchids never want to dry completely when in growth. For these, smaller particle sizes work better. This includes most Dendrobiums, Oncidiums and their intergeneric hybrids, Paphiopedilums and Phragmipediums.

Potting media used can be any of these alone or in combination: Bark, volcanic cinders or scoria, clay balls for horticulture called LECA, horticultural charcoal, perlite, pumice. Many of these are sold in different sized particles. They all have various advantages and disadvantages.

Sphagnum moss also works well as a potting medium for most orchids, but watering plants in sphagnum is very different from watering in particulate media, so that is a different topic.

Thank you so much for explaining!! (: