Question
I purchased a gardenia from Costco.  It was from a nursery in Santa Barbara, CA.  I have watered from the bottom as you suggest.  I have wonderful buds, but as they bloom I have seen spider mites and now webs as the blossoms open totally.  I have been told to use a weak solution of water with detergent to spray on the plant and then rinse with warm water spray.  Also, that I should protect the dirt from the spray with soap.  Is this the best and least invasive way to manage the problem?  This is the first time I have been successful at all with a gardenia and I don't want to loose it.  It is in the kitchen with windows that face east and south on two sides.  It is a two gallon pot, it has grown a lot in a month, how much water should it be given and how often?  I noted you info about the vinegar and will add that to the schedule.  Thanks so much!  Carol

Answer
Bottom-watering has many benefits, but I don't think I have ever recommended it for Gardenia watering.  Reason being, Gardenias need high humidity.  Without a LOT of moisture in the air, the leaves drop and the plant fails.  These are MADE for the kind of air that could make you feel like drowning.  University of Rhode Island experts at the URI Greenshare website point out, 'High humidity is essential to gardenia care. Avoid misting the foliage, though, as leaf spot fungal problems will develop.'  Here's the website:

http://www.uri.edu/ce/factsheets/sheets/gardenia.html

Watering Gardenias is another trick of the trade that's hard to master.  Notes URI, 'The soil should be kept uniformly moist, but don抰 overwater.'

And how does this apply to your Spidermites problem?

Spidermites thrive on DRY air.  The kind that Gardenias can't handle.

What's more, Spidermites exposed to prolonged periods of Humidity KICK THE BUCKET!  Totally True!  The moisture that URI warns you to avoid to keep Fungus from growing is why Spidermites fall apart in Humid rooms -- they are ATTACKED BY FUNGI!

Wild, huh?

Now I'll give you something to really worry about.  Let's look at the URI page on Gardenias first: 'The most irritating problem encountered with Gardenias is bud drop, when flower buds abort just before blooming.  Common causes include low humidity, over-watering, under-watering, insufficient light high temperatures, rapid temperature fluctuations, cold drafts or change in plant locations.'

See that line about Low Humidity?  See what they say about over- or under-watering?  H2O management is THE KEY to successful Gardenia-growing.  And you are ALMOST there.  Close.  But NO CIGAR!

You have GOT to get that moisture management under control, or those Buds you successfully triggered (5 stars for you, by the way!) will drop like flies off your Gardenia.  This is one of life's great disappointments.  So close, yet so far.  You have ALMOST PERFECTED the art of growing these.

Dishwashing liquid diluted (big time) with H2O and sprayed on leaves will indeed repel Spidermites as well as Aphids and any other pests you may come across.  But to me, the mites are a symptom that your air is just too dry and the Spidermites are a barometer of that condition.  Watch the leaves closely.  If they start to drop or brown up, it is time to push the panic button.  Write back.  For now, it seems you're pretty safe.  See how the spray treatment works.  Long term, you will have to figure out what to do about the humidity in the air.

As for watering, Vinegar is highly acidic -- critical for Gardenias because they cannot absorb Iron if the pH is normal.  Iron is only a trace element, but it is needed for formation of Chlorophyll.  Unfortunately, Iron is only usable by plants in a very specific form which I'll describe as an Fe2+ ion. Iron is useful only when the pH of the Soil that contains it is between 5.0 and 6.5.  But be VERY careful with the Vinegar.  It is SO EASY to over-do it.  Get yourself some Aquarium pH paper and figure out how much you should add to get the pH down, but not LETHAL.

With respect to how much Water, how often, etc, this is tricky.  The potting medium is probably quite water-friendly, perhaps amended with Peat moss or something else that holds moisture.  Let it dry out once or twice a month to make sure there is air available to the roots.  Lukewarm water is ideal.  Since this plant is potted, you will have to figure out a system of fertilizing.  Although it can stink to high heaven, Fish Emulsion, gently administered after periods of flowering to help build leaves and replenish Nitrogen, is in my opinion a very nice treatment for these plants.  Before and during periods of bloom, a handful of Superphosphate will help.  When repotting, throw in some Bone Meal and Alfalfa or Cottonseed Meal to enrich the Soil.

That said, it does sound like you are in the driver's seat, despite this small Mites affliction you are dealing with (probably very capably).  These are heavenly in the home.  You are getting the hang of it very nicely from what you've said so far.  Keep in touch and let me know how it fares through the change of seasons.  Thanks for writing!