There are about 35 species of aeoniums in the world. After collecting 26 of the species, it's time to move on. What's a plant collector's next compulsion? Who knows. (Ron Vanderhoff, Daily Pilot / March 11, 2011)

What's wrong with me? I just dumped another horticultural ambition.

Four years of hard work gone in one afternoon.

Is there anyone else out there with a similar diagnosis? Four years ago I became fascinated by a rather small group of succulent plants, known as aeoniums. Several of you may know a few of the common versions. One day, while pondering aeoniums, I somehow concluded that I would set out to see how many different species I could assemble.

I even briefly considered a collecting trip to the Canary Islands, where several grow. Yikes! Is this a disease?

Depending upon the authority, there are about 35 species of aeoniums in the world. Two or three are pretty readily available, and most of you have probably seen them. These two or three, and their hybrid selections, are about all most gardeners might know about this interesting group of plants. Another six or eight species can be acquired with a credit card, an Internet account and a lot of blind faith. The next 25 species are obscure and essentially unobtainable.

As of this week, I've obtained 26 aeonium species. If there was a gold medal for aeonium collecting I might own it. Unfortunately, nobody really cares much about aeoniums. A big collection is about as impressive as a big collection of lint or maybe a world class assemblage of tongue depressors.

I've been fascinated by plants since I was about the size of an aeonium undulatum. My first significant obsession was with fuchsias. By 17, I had built a lath house in the backyard, joined the National Fuchsia Society and had begun amassing a huge collection of hybrids, each carefully labeled.

By my mid-20s, I was already in my addictive spiral of transitory plant cravings. Not sure how these interests germinated, but somehow I would become drawn to a particular group of plants. Within weeks, I would become so engrossed in these plants that I would be up late at night reading every catalog and searching every book possible, learning all I could. I would join societies devoted in some way to these plants, visit arboretums, write letters and consume every scrap of information I could unearth.

Meanwhile, my plant assemblage would begin.

Do any of you share this compulsion? I hope I'm not alone. Sometimes these plant lusts would last for a year, sometimes for two; occasionally the obsession would persist for four or five years. Then, without warning, a new group of plants would catch my fancy and a new craving would initiate. Usually I could simultaneously balance three or four obsessions like spinning plates, but eventually the addition of a new plant interest would cause an older plant interest to extinguish. One can only keep so many plates spinning at one time.

I remember the passions well, and I still have many records of the plants that ensued: sweet peas (95 varieties), agaves (38 varieties), tomatoes (211 varieties), aloes (84 varieties), amorphophallus (17 species), campanulas (30 varieties), oxalis (354 species and varieties — yes, that's right), clematis (32 varieties) and sedum (46 varieties).

That's just a few; several other obsessive and transitory plant passions occurred over the past 30-plus years, but most of these were before I kept records, so the plant counts are unknown: delphiniums, alstroemerias, amaryllis, brugmansia, erodiums, salvias, true geraniums, pittosporum and plumeria, to name a few.

Currently, my cravings include some pretty obscure plant groups, like dudleyas, calochortus and lachenalias.

How many can I grow? How long will my interest last? What will be the next plant to catch my fancy? Which spinning plate will have to fall?

I don't have the answers, but there are a few more plant groups out there that have caught my eye recently.

Which brings me back to the aeoniums. The pursuit is over, and the collection has been dismantled. The spinning plate has stopped spinning.

Tuesday, while staring at the 26 species, I was faced with a choice: repot most of them to larger containers, or stop the insanity and move on. I'm moving on. On Sunday, 14 of the 26 species are going to work with me, where they'll be offered to co-workers. Four years of effort will come to an end tomorrow. No regrets; it's the race that matters, not the finish line.

Hmmm, brodiaeas looks interesting . . . so do fritillarias. I wonder how many I could …?

RON VANDERHOFF is the nursery manager at Roger's Gardens, Corona del Mar

Ask Ron

Question: I've heard that adding old coffee grounds to my soil good as a fertilizer. Is that true?

Grace

Costa Mesa

Answer: For the most part, yes. Coffee grounds are ground organic matter. Generally speaking, ground organic material is the basis of soil improvement. However, coffee grounds should not be considered a fertilizer, as the nutrient value is minimal.

Coffee grounds can slowly help to acidify the soil, especially if added around plants that prefer a low pH, such as azaleas, camellias and blueberries. Tossing the used grounds directly onto the soil is OK, but can be unattractive. As with any organic matter added to your soil, it is always best to allow the product to compost for a while before adding it to the garden. And continue to fertilize, since coffee grounds are a soil amendments and acidifier, not a fertilizer.

ASK RON your toughest gardening questions, and the expert nursery staff at Roger's Gardens will come up with an answer. Please include your name, phone number and city, and limit queries to 30 words or fewer. E-mail stumpthegardener@rogersgardens.com, or write to Plant Talk at Roger's Gardens, 2301 San Joaquin Hills Road, Corona del Mar, CA 92625.