February Orchid Care vol. 1

orchid care calendar

February

1. Repot autumn flowering orchids.

If your orchid flowered this past autumn (like the Paphinias above) it's time to take a closer look to see if it has produced a new shoot. A new shoot is your signal to repot --if your orchid has outgrown its pot or if the potting mix has broken down. Most orchid potting mixes with organic ingredients (bark, moss) only last a couple of years before they start to retain too much moisture.

2. Watch out for slug damage.

The slug population in our display and back up greenhouses goes berserk during cool wet weather. They are enemy No. 1 in winter. Here's what I tried --what's worked and what hasn't:

• beer (cheap, expensive, light, dark, imported, domestic). Even though it's kind of fun to offer your enemy a poison-laced skol, I've always been disappointed with the results. 
• the overturned cabbage leaf; the inverted melon/grapefruit rind, the potato/apple slice; inverted clay pots. No luck with any of these in our display greenhouse.
• iron phosphate. Relatively non-toxic to animals. But I still find live slugs in pots that I have treated with iron phosphate.
• metaldehyde (the active ingredient in lots of slug baits). It works. It kills slugs. It kills frogs. It's dangerous to people, too, at high enough concentrations. With repeated applications you select for resistant slugs. We don't use it any more. If you're buying retail slug killer, be sure to check the label for the active ingredient.
• laboratory grade caffeine. No kidding. A scientific publication a few years ago documented the effectiveness of concentrated caffeine (a clear odorless liquid available from laboratories) at killing slugs. So we tried it. On the slugs, I mean. Yes, it works, but I'm just not comfortable having the stuff around.

I haven't tried the predatory decollate snails that eat our native mollusks. Before trying this I would need to resolve my concerns about introducing non-native fauna into our area.

Honestly, the only treatment that has ever worked for me is physically removing the slugs --repotting and replacing all the soil-- and keeping things drier. It helps to know what slug eggs look like. They look like clusters of tiny (1 mm) pearl onions.

4. Come to our Orchid Care Clinic.
How is your orchid doing? Have you ever looked for advice on the internet and given up because it just doesn't seem to apply to your plant? Have you ever wished for a walk in clinic for your orchid? where you could bring your orchid and get personalized advice? or have someone show you how to repot your plant? It's here! This Saturday.

• Atlanta Botanical Garden's Orchid Care Clinic
• Hardin Visitor Center, upstairs
• Saturday February 9, March 9 and April 13
• 10 am to noon
• $5 if we repot your orchid

See you there!

January Orchid Care vol. 2

orchid care calendar

January

Tempting though it may be to slack off rest during January or lose myself in orchid displays and spring catalogs, I know I will regret it if I take my eye off the greenhouse. Here's what's on this week.

4. Create a calendar for plant care.

I love creating a calendar for our plants. And while we often deviate from our schedule (postponing fertilizing if it's dark and rainy), or don't commit in writing (repotting and staking depend on developmental stage and therefore are indirectly weather dependent), it's often true that what doesn't get scheduled doesn't happen.

5. Remember to monitor for scale insects.

They're not sleeping. They've just slowed their reproductive cycle as the days have gotten shorter and cooler. But they are not going away if you ignore them or if you treat them only once. Scale are incredibly tenacious. And they will kill your orchid if they are not controlled. If you have a few now, you will have massive numbers by late spring. So roll up your sleeves and jump into the trenches. This is war.

• Remove the adults. If your orchid has tough leaves like the Laelia (above) you can remove the adults by nozzling the leaves. A shut off valve on the hose helps to concentrate the water flow. Scale insects on soft-leaved orchids can be gently massaged off of the leaves.
• Write a spray schedule on your calendar.
• In the winter spray every two weeks over a six week period.
• In spring and summer spray weekly for a month.
• Use Neem or horticultural oil at the dosage recommended on the label. Make sure your plant is well watered the day before you spray any oil product.

6. Stake Phalaenopsis (Moth Orchid) spikes.

A spike with fully developed flowers is heavy and needs the support of a stake. If you wait until the spike is mature you could end up with a spike that is bent like a crazy drain-pipe. When the young spike is six to eight inches tall you will need a 30 inch stake and a twist tie or clip. We love daisy clips {see Ties at this link} a terrific time saver when you have lots of plants to stake. When the spike reaches 12 inches its time for a second tie/clip.

January Orchid Care

orchid care calendar

January

It's hard not to feel a little exasperated, maybe even a little worried, about your plants by mid winter. You can't remember the last time you saw a new leaf or new root, let alone a flower spike. C'mon, guys. What do you want from me? Here are some simple things you can do to make them happier.

1. Give your plants more light.

If you're like me, and given to whining talking about what must be the darkest winter in recorded history like it's a personal affront, then pity the poor tropical plants that have to endure winter in the north temperate zone. Even in Atlanta (33N latitude) the days are short and the light is feeble compared with a winter day in the tropics. We've been busy washing glass and pulling back shade cloth. You may not have algae on your glass like we do, but what about air pollution, pollen and canine nose smears...? Be sure to move your plants closer to the window, open the curtains and wash the glass.

2. Drop the temperature. 

On dark winter days you can definitely get away with dropping the daytime temperature by 5º. Your plants won't even notice. But some orchids, the real sleeping beauties, need some serious rest --a cool dry rest-- in order to set buds. How cool and how dry and how long depends on the orchid. 

• Dendrobium nobile (top), which sheds some of its leaves in winter, wants nighttime temperatures below 57 º for four weeks, and water when almost bone dry. 
• Dendrobium anosmum (middle), which sheds all of its leaves in winter, wants 50-55º and water when bone dry for six weeks. 
• The Catasetinae (Catasetum, Clowesia, Mormodes, Cycnoches) (bottom), want a slight , i.e., 5º drop in temperature, and less frequent watering until the new vegetative (i.e. leafy) shoot is several inches tall. The rest usually lasts four to eight weeks.

3. Don't forget late season repotting.

Orchids that flower in late summer --like Cattleya maxima, Miltonia spectabilis and many Stanhopea-- produce new growth in fall and winter. If you forget wait until spring to repot, you will have missed your window of opporunity until next fall, by which time the potting mix will look like soggy Grapenuts and possibly kill your plant. Even though it's winter, keep checking your plants for new shoots, the signal that it's time to repot.