Plumeria Potpourri The Plumeria Society of America May 7th Meeting Tuesday, May 7, 2019, 7:00 p.m. Cherie Flores Garden Pavilion, 1500 Hermann Drive, Houston, Texas ... anyone with an interest in plumeria is invited to attend ... Speaker: Emerson Willis Title: A Salute to Sergeant Guillot May 2019 President’s Corner p 2 Part 2: Making the Most Out of Slow Release Fertilizers— p 3 George Hadjigeorge Sun, Sand, and the Sea—Emerson Willis p 7 The Plumeria Part 7: Plumeria Obtusa— p 8 Donald R. Hodel President’s Corner by Ray Allison ([email protected]) With plumeria beginning to leaf out and inflos peaking, the spring growing season we love is here. Emerson Willis, a plumeria gentleman and Lifetime Member of the PSA, will be our speaker for the May 7th meeting. Emerson will take us into the PSA history files as he speaks about another plumeria gentleman and Lifetime Member of the Danny Kashou photo by PSA, his dear friend, Bud Guillot, now 97, living in Huntington Beach, California. We will hear about many things: Bud’s early years in Paris, Texas; his bombing missions in a B-24 during World War II and time spent as a POW Emerson Willis and Bud Guillot in Stalag 17; a 60-year old plumeria tree in Bud’s front yard, originally found for 99 cents as a green A Salute to Sergeant Guillot paraffin-covered stick in a war surplus store; and One plumeria gentleman and Lifetime PSA Member, Emerson Willis, will talk about another plumeria five registered plumeria—‘Guillot’s Sunset,’ gentleman and Lifetime PSA Member—his dear ‘California Sally,’ ‘San Miguel,’ ‘Saigon Moon,’ and friend, Bud Guillot. ‘Makaha Sunn.’ For those of us not aware of this wonderful plumeria history, Emerson’s presentation to publish and mail the print newsletter. will be one to remember. As plumeria wake up and bloom, this is also a For our July meeting, our speaker will be the popular time of year to renew your PSA head horticulturist from the Houston Botanic Garden. membership—remember, you can always go to our By popular request, we will continue producing website to renew. and emailing a low-resolution electronic version of Stay tuned for 2019—more fun to come as we our print newsletter. If we don’t have a good email celebrate the 40th anniversary of The Plumeria address for you, please let us know. We will continue Society of America. 2019 Houston Area Plant Sale Calendar Southwest Clear Lake Sale (1st sale) Fertilizer April 30 Commitment to sell at Clear Lake BOB PATTERSON May 7 Sellers’ meeting after the general meeting 5828 Bissonnet May 29 Cultivar list for Clear Lake sale HOUSTON, TEXAS 77081 TEL: (713) 666-1744 FAX: (713) 666-8108 June 8 Sale at Clear Lake VISIT US ONLINE @ YARDGEEK.COM Clear Lake Sale (2nd sale) 10% DISCOUNT for PSA Members July 2 Commitment to sell at Clear Lake Southwest Fertilizer is celebrating July 9 Sellers’ meeting after the general meeting 63 years of operation. PSA members receive a July 10 Cultivar list for Clear Lake sale 10% discount on fertilizers, soils, and tools. July 20 Sale at Clear Lake Each year in February there is a plant society Contact: Renee Riley appreciation week—members get a 15% discount. [email protected] 713.485.9652 2 | www.theplumeriasociety.org | May 2019 Part 2: Making the Most Out of by George Hadjigeorge, Texas Slow Release Fertilizers How about larger pots? I measured the soil Time of Ambient Soil Soil temperature 1.5” below the surface and 6” below the Day temperature temperature temperature the soil surface in the center of the pot, away from ˚ F. in full sun @ in shade @ the wall. For a 35-gallon pot with ambient 1.5” , ˚ F. 6”, ˚ F. temperature of 87˚ F. and lower night time 7 a.m. 78˚ F. 78˚ F. 78˚ F. temperature of 75˚ F. the soil temperature was: 8:30 a.m. 80˚ F. 86˚ F. 79˚ F. 10:30 a.m. 84˚ F. 92˚ F. 82˚ F. • In the shade all day—84˚ F. at 1.5”, and 80˚ F. at 1 p.m. 92˚ F. 100˚ F. 92˚ F. 6” below the soil surface. 3 p.m. 92˚ F. 100˚ F. 92˚ F. • Semi-shade all day—94˚ F. at 1.5”, and 84˚ F. at 5 p.m. 92˚ F. 100˚ F. 92˚ F. 6” below the soil surface. • In sun most of the day—100˚ F. at 1.5”, and These data show some interesting trends: 90˚ F. at 6” below the soil surface. a) At night the soil temperature went down to the • For a black 3-gallon pot in the sun—100˚ F. at lower ambient temperature. Typically, in the -1.5”, and 94˚ F. at -6” from soil surface. summer in the Texas Gulf Coast this is about 80˚ F. • For a 10-gallon pot in full sun—102˚ F. at -1.5”, b) As soon as the sun rose and the rays hit the pots, and 95˚ F. at -6” from soil surface. the soil temperature rose quickly above ambient • For a 30-gallon pot in full sun—100˚ F. at -1.5”, temperature by absorption of radiation from the 94˚ F. at -3”, and 86˚ F. at -6” below the soil surface. sun. Eventually the soil reached 100˚ F., which dropped lower after the sun went down. In other words, larger pots did not get as hot as c) The temperature of the soil in pots in the shade, smaller pots. Their temperature was limited to a which were not exposed to sunlight, stayed at maximum of about 100˚ F. at 1.5” below the soil line. about ambient temperature during the day, which The temperature of the soil was significantly lower was about 8˚ F. cooler than pots in full sun. deeper into the pot. At 6” below the soil line, the soil I made a lot of temperature measurements temperature was about 10˚ F. lower because the during July and August, and they all showed the heat had to travel down there by conduction through same thing. Larger pots did not get as hot as one- the soil from the soil surface and from the pot wall. gallon pots—the soil temperature was limited to This means if the slow release fertilizer is mixed 100˚ F. at 1.5” below the soil line. Shading large pots with the soil during re-potting rather than being was a good thing and reduced the soil temperature spread at the soil surface and covered with mulch, it by about 8˚ F. So, at 1.5” below the soil line, the will last about one month longer. average temperature of large pots in full sun during How does the temperature of a large pot vary the summer was about 90˚ F. (100˚ F. during the day as a function of time during the day (so we can and 80˚ F. during the night), which reduced the life of calculate the average temperature of the pot)? These slow release fertilizers by about 2 months (20 degrees measurements were made May 30th with a low above the base of 70˚ F. and one month per ten ambient temperature of 78˚ F. and a high ambient degrees rate). If the pot was in the shade, the temperature of 92˚ F. average soil temperature dropped significantly to an average of 86˚ F. (92˚ F. during the day and 80˚ F. at May 2019 | www.theplumeriasociety.org | 3 night). Shade extended the life of slow release As I explained above, the expected life of slow fertilizers by about half a month. release fertilizers is greatly affected by soil What about the temperature of the surface of temperature and exposure to the sun. What can we the soil? That was very hard to measure with the do to make the most of slow release fertilizers and probe because most of the probe tip was sitting in make them last for the whole growing season? the air. However, we can get an idea from The most important thing we can do is to observations. Sand on the beach has the same total protect slow release fertilizers from exposure to the emissivity as mulch or soil at 0.8. Thus, the pot soil sun. This can be accomplished easily by covering surface will absorb the same amount of radiation the fertilizer with 2–4” of mulch. Hardwood mulch from the sun as sand on the beach. You know how packs and works the best. In addition to protecting hot the sand on the beach gets at 3:00 p.m.—you the slow release fertilizer from the sun, the mulch cannot walk on it bare footed. We are talking of a also keeps the roots cool, it prevent weeds, and temperature of the order of 150˚ F. or higher. The soil keeps things like perlite from floating during surface temperature gets so high it often sunburns watering. Mulch is good for both plants planted in the base of the lower trunk of plumeria plants by the ground and for plants grown in pots. In pots that reflecting radiation onto the trunk from the soil are not re-potted in the spring, slow release fertilizer surface, which becomes additive with the sunlight can be spread on the surface of the soil mix that falls on the trunk. It takes very high soil surface according to the manufacturer’s recommended temperature to cause sunburns. Note that for the soil amount. It is best to use a gardening tool to work the surface to radiate heat onto the trunk it must be at fertilizer into the soil.