Paul Kroll's Talk

Notes from Paul Kroll's Visit to the Twin Cities

September 2014

We started out with learning what to do with the cuttings you bring home. Paul uses an Exact-O knife to slice the cutting's petiole slightly and he sticks it back in the bag. He puts 2 or 3 drops of Super Thrive in some water and puts a little of this in that same bag and leaves it over night. After the cutting has revived and gotten turgid again, he washes the cutting (leaf or larger cutting) with either a mild soapy mix using Dawn or Ivory dish soap or even some Fels Naphtha soap. The cutting is rinsed very well to get all residue of the soap off and then it's planted in mix after the petiole is cut rather short. Paul doesn't use a rooting hormone or Clonex like others including Mel Grice sometimes suggest. Paul's mix comes from an old publication where Carol Schreck's recipe was published. It is made of perlite, vermiculite, milled sphagnum and charcoal. Rooting from bloom stems is more difficult and they sometimes go into just sphagnum moss.

Paul makes his own mix in which he uses some real "soil". In other words some organic material. Plants seem to get big when there is more than just the typical "soil-less" ingredients in it. His mix is an amended mix like the Fischer's, although amended even more to make it less dense. Paul waters his rather large collections each Monday morning by filling saucers, letting them stand and then pouring off any excess in the trays to lend humidity to the area. His growing area is in the basement of his home in an approx. 15' x 15' bedroom-type space that has bright white painted walls and the 7 light stands he uses. He fills his water in 5 gallon plastic containers and then adds the the type of fertilizer he's using at the time (for a feeding with each watering) and a drop of Super Thrive per gallon of water. He varies his fertilizer between brands as Peir's 20-20-20, Peter's Pro 15-16-17, Champion 20-10-20, Miracle Gro Tomato formula (which is pink) and some from Cape Cod Violetry with no urea. About once a month he puts in some Epsom Salt (magnesium sulfate) which seems to keep and promote leaf greenness. The rate was 1/4 tsp (but I didn't catch per gal, or per 5 gal bucket.) The Epsom Salts might also act to keep the soil pH more even. Other items such as distilled white vinegar at a rate (for him) of 1 tablespoon per 2 gal of water, may be used to keep pH in a desired range. The range that was discussed to make nutrients most available was 6.8 to 7.2. There is a large violet book by Melvin Robey which includes a very informative chart about which nutrients are available at which pH. Paul gets the water to the plants using a pump in the big buckets and a rubber fuel line hose (as opposed to the clear plastic tubes which get discolored and tend to kink more. Auto part stores carry the black rubber tubing. There were questions about some of the methods used and a tip for getting your Epsom Salts dissolved was to use hot water for dissolving and then be sure to cool the water before using on the plants. Paul puts a diffuser grating over trays on his shelves. On the grating he puts his plants in individual saucers. he adds water from the bottom, lets the plants soak up water and then later he empties any remaining water into the trays under the grating so that there is humidity around the plants. 

His growing area is typically 65° at night and 75°- 80° during the day in the winter months and warmer, 72° at night and perhaps up to a high of 85° during the summer. The lights help to heat the room and Paul's switched to from using all old T-12's to using more of the slimmer T-8's. They give off somewhat less heat than the larger bulbs but are brighter. Also, he has a few T-5's which are very bright but tend to be hot. The 4 tube T-8 fixtures which are quite bright are good for growing many Gesneriads which like a bit more light than African violets. Typically, a 10 to 15 degree temperature change in 24 hours is acceptable to most plants. All Paul's plants get the same fertilizer and similar environment. Sometimes his room is up to 80% humidity but there is always air movement from fans that are pointed up going 24/7 in the room. He does use some granular pesticide (Imidacloprid) which is placed on the top of the soil and very sparingly moistened in to not leach it through the soil. Now, instead of using Kelthane sometimes for mites, Avid or Conserve is used as needed. The lights are on 12 hours per day year round.

Paul discussed using "pot alternatives" for cost savings and as a good way of recycling. He demonstrated using very shallow pots and sometimes even cutting down typically shallow pots such as azalea pots to make them slightly shorter yet. Many Gesneriads such as Episcia are shallow rooted. He had a neat trick of spray painting the clear cups, such as Solo Cups, with a green Krylon spray paint that really matches the typical commercial green pots. This is great for shows etc. The Dollar Store has some plastic soup bowls etc that server very well for different planting containers. Drainage is put in all such containers. Paul showed a couple of neat tricks. He keeps a wad of dental cotton (the stuff the dentist puts in your mouth to absorb moisture) on each shelf to blot up any drops on leaves etc. They can be used over and over. When asked about repotting, Paul says after the plants are of a mature size he repots at least once a year.

Paul brought an AMAZING array of leaf and stem cuttings to share and distribute to our members. We drew numbers and then took turns picking up our choice of fabulous things. In the violet leaf line there were such leaves as some rare older ones such as 'Amazing Grace', 'Harbor Blue' and a mosaic variegate 'Lillian's (something). There were many different species varieties available. What a treat to have these and what a very generous and awesome thing for Paul to share so many of his plants with us. A special thank you to him for this. Wow.

We heard about various smaller topics here taken from audience questions. He goes through over 1200 baggies (or 1200) donated leaves and cuttings given generously to various clubs and seminar groups a year. To keep interest in their clubs they have a couple of activities that we don't such as Blossom Shows, where people bring blossoms to the meetings to display instead of an entire large plant and various club projects along with things we do do like leaf exchanges etc. Tips on how to hold leaves for future events were discussed too.

We heard about the different root types for gesneriads. ALL gesneriads have fibrous roots and some have fibrous roots and additional structures such as tubers and rhizomes. An interesting fact we learned is that a plant that produces rhizomes must bloom before it starts to form any new rhizomes. If you happen to kill the plant before it blooms it will not have any rhizomes under the soil to try to resprout and start again.

Another interesting thing we heard is that the vining and more epiphytic plants such as Aeschynanthus, Columnea and Nematanthus are grown with no extra lime added to their soil. Plants like the Boeas, Gastranthus, Petrocosmeas, Gesneria, and Primulina seem to benefit from extra lime add to the soil mix because of how they grow in their natural habitat.  As a guide, 1 cup extra powered lime is added per bushel of soil mix (or about two 5 gallon pails worth) and 2 cups added if your normal water is not on the alkaline side. The lime used is the typical stuff you find at nurseries or garden centers in bags in the plant care section. 

Next we heard about the various methods of propagation. Paul had lovely diagrams and talked us though the ways to put down different types of plant leaves and cuttings. I can't reproduce the pix here, so you'll just have to imagine!

Paul brought a number of very interesting plants and what generosity! Much and many thanks for the opportunity to try some of the newest and most interesting! This was a great opportunity and I sure hope that we can again have Paul back for another great seminar. Thank you Paul!!