watering cattleyas
 

I am new to the forum and have been a "casual" orchid grower for years. Now retired, I would like to learn more about what I have been doing and decrease the rate at which I kill orchids. I have about 60 plants, mostly cattleyas or laelia cattleyas, with 6 or so phalaenopsis, and a smattering of other plants. They are housed in a two sided greenhouse facing south-west (The north and east sides are the house walls and door). There is a mist spray system, kept at about 40%. Temperature is about 80* in the day and 60* at night. The cattleyas are planted in course bark mixture and most pots are clay. I have never understood how often to water. The planting mixture, to me, always seems dry and my instinct is to water every day, yet I read "water once a week". Is there an ideal routine? How often to fertilize? I know this is a hugh topic, with no "one size fits all" answer, but I would appreciate some thoughts.
Thanks, Ed

:waving Hi Ed. Welcome to the Orchid Board!

Indeed, watering is tricky for all the reasons you mentioned. Here are a couple of ways to determine if your orchids needs water; and remember when in doubt, don't water.

1. Dig your finger into the potting mix a little bit. Does it feel damp? if yes, then no water needed

2. a wet pot is heavier thana dry pot. so lift it up and see. in time you will be able to tell by the pot

3. is the clay pot cool or damp to the touch. Water evaporates through the clay and lowers the temp of the pot itself. So a clay pot should feel very dyr before watering

4. Use a bamboo skewer (the kind you can get at the grocery store for BBQs) and poke it into the pot. Does it come out wet/damp?

How fast things dry out is also dependent on air circulation. if you have fans that are circulating the air, the pots will dry out a little faster too.

If the bark dries out evenly and isn't just dry on top, you can water when dry. In the larger pots, I often put an upside-down net pot in the bottom and middle of my pots to help keep the roots in the middle from staying to wet. I also grow all my orchids in plastic 'basket' pots or mounted. I use lava rock because the house gets cool in the winter. I give my cattleya family orchids extra calcium (oyster shell, egg shell, etc) and use an MSU formula. I add Epsom salts now and then, as well as dissolved Ironite. Flushing pots is important with the non-organic fertilizers as salts from the fertilizers can build up.

The lead pseudo-bulb is a good indicator of hydration. It should be plump. If it shows signs of wrinkling, it's not getting enough water. Don't worry about the pseudo-bulbs at the back of the plant. They're almost always wrinkled. I like my cattleyas to dry very quickly so I use clay pellets (LECA) in clay orchid pots with plenty of drainage holes. During the spring and summer I water these plants twice a week. I water heavily so it gets very wet but my media dries completely within 24 hours, maybe less. During the winter I water about once a week. Maybe a little more often. My cattleyas that are not in pots are mounted on cork or tree fern fiber. I water these every morning during the summer and about every three or four days in the winter. I also have some in open wood baskets and these get watered a little more than the pots but not every day. I fertilize once a week during the summer. In the winter I use a weaker dose and fertilize every two weeks. If the cattleyas are in temperatures below 60 degrees, I don't fertilize at all.

:welcomeflowers: Glad you found us!

I think that the bamboo skewer is the best method for beginners to determine moisture in the media. Easy and cheap and accurate.

I agree. This has helped me save all my orchids from root rot. Mine get a cool winter and that's when I was watering too much. I have some in clay pots because they have a nice heavy base then. But I prefer clear plastic pots with either cones in the centre or very good drain holes in them for most of my catts and other orchids. I just got very used to seeing the roots and knowing what is going on.

I usually fertilize at about 1/2 strength (from what the container says) weekly and every month I flush the pots well to remove fertilizer salt.

with your conditions I would stick to a once-per-week watering schedule and ensure that water runs out the base of the pot for each orchid. Ideally too the water should be about 75f - I use an aquarium heater to keep the temp consistent.
Fertilise weakly weekly ( 1/4 recommended dose ) and in the 4th week don't use any fertiliser.
Light is important - make sure that your catts ( more ) and phals ( lesser levels ) are getting the right amount.

As you can see there are many suggestions, you have to find one/combo that isn't too onerous to keep to !

Welcome Ed!!!!

Your temps are very good for Catts. Humidity is abit low. 70-80% is ideal. If you raise your humidity you can unpot your plants from your potting mix and stick the plants in clay pots bare root with some large broke clay pot pieces if needed. I suspect your having problems with your plants is that your bark has "bad" bacteria growing in it. These is very common. If thats the case I would unpot your plants, remove all bark. Then remove all bad roots and soak your plants in diluted mixture of H2O2 or Physan 20. Allow them to dry out for a few days. I would also clean your greenhouse from head to toe. Big chore... Yes, but it will need to be done! Also, Do you have fans?

If you do decide to pot them with no bark(which I thing is a fool proof way of growing Catt's) and have very good air movement, you can water them every other day or so. As long as they dry out. You'll need to experiment to find the right watering schedule. Since you have a misting system you can hook up a humidistat to keep your humidity in range. IF your afraid of overwatering than you put some misters under the benches pointed out for humidity control. I would also lengthen your water time to 15-25 min twice each watering day. Remember that Catts and Phals for that matter, grow bare root on trees with heavy down pours almost daily.

Humidity and air movement are the key.

I've found that this method works out very good for growing great roots. Great roots = Great Plants = Great flowerings

I would also mention that fertilizer choice and water quality are big to growing great plants. I would recommend K-Lite or MSU fertilizer sold by First Rays @ 30 PPM N every watering. If thats is not feasible than 65 PPM N once a week will work. Having "soft" water is very important. You can test your water with a simple TDS meter. I would recommend a TDS <100 PPM for Catts. If you water quality is higher than that, then I would recommend an RO system. If your going to grow any Pleuros, Draculas, Phrags or such, then you need RO or TDS of 20 PPM or less. I will also recommend using seaweed or kelp extract and beneficial bacteria product like SubCulture B . Great for roots