Wreath making has arrived! When November rolls around students learn how to look at plants in a whole new light. Instead of thinking about landscape usage and sun or shade conditions, we think about bling and flair, color and texture for a holiday wreath. It starts with collecting the bones of the wreath or the green boughs that will make up the major portion of the wreath. For this we use Leyland Cypress, Douglas Fir and Western Red Cedar. Luckily a windstorm recently swept through Western Washington and we benefited from windblown branches that had been knocked to the ground. These are great because they are from the top of the trees, have received lots of sun and have nice full growth. Good wreath material! After collecting the greens, we scour the campus and surrounding areas for accent plants. Holly, Beauty Berry, Karl Foerster Grass...anything that provides a touch of individuality to the wreath. Students learn that many of the plants they have been studying all year can combine to make an amazing wreath. Nothing is better than presenting loved one with a wreath made from xCupressocyparis leylandii, Gaultheria shallon, Psuedotsuga menziesii, Lanvandula angustifolia, Corylopsis pauciflora, Cornus sericea and, of course, Callicarpa bodinieri, a class favorite. Wreath making has become a favorite Horticulture holiday tradition.
This Fall our students have a special opportunity to learn about the world of irrigation. With the help of Cascade Water Alliance and instructor David McGrath, the students are using the irrigation learning lab in the arboretum to understand equipment, repairs and control settings for a standard system as well as a drip system. We hope to continue to use the irrigation lab to train our students as well as other local industry groups. On this day students learned how to adjust a sprinkler head so it sprays water in the right place. They also adjusted the placement of a sprinkler head that was several feet away from the bed, bringing it closer with a funny pipe and new fittings. Finally students learned how to deal with a broken pipe, cutting out the leaky piece and gluing together the new parts. As students become familiar with the different parts of an irrigation system they are better prepared to make repairs on a job or install a drip system in their own yard.
This week in class students acted out the growth of a tree. They became cork, cork cambium, phloem, vascular cambium and xylem as they transported sugars, created new cells, protected the outside of the tree and moved water. Now they will never forget what is going on inside of a tree!
Horticulture students have many talents and this year they produced a bountiful harvest of fruits and vegetables. Every summer students are given the opportunity to grow a garden in the small plot and grow boxes on the West side of the greenhouse. Even though we discuss growing vegetables in our classes, the summer garden is independent of the curriculum. Students form a garden team and plan what they will grow and take full responsibility for the care of the garden all summer and into the Fall. They often start seeds in the greenhouse in May and transfer the seedlings to the beds by June. The weeding parties begin then and by hot July and August they are diligently dividing up watering duties. August and September still have a lot of work as they harvest and then begin to clean up and prepare the beds for winter. This year they grew squash, watermelon, beets, peppers and a never-ending supply of Sungold Cherry tomatoes. After the students took what they needed for their families, the remainder of the harvest was donated to the local food bank. For some it's their first time to grow vegetables. Working with others and receiving advice from the horticulture staff, they receive a valuable education and are ready to continue growing food in their own gardens in the years to come.
This week as we study greenhouses we had a terrific field trip to T & L Nursery in Redmond, Washington. The general manager Andrej showed us through the shipping area, the propagation house, the old and the new greenhouses as well as the extensive outdoor growing area. It was fascinating to learn about the history of the greenhouses and how each one serves a specific purpose. Some are for warm growing in the winter, others just to keep rain off plants in the spring. We saw vents and side flaps, heating and cooling systems, irrigation and learned about the computerized environmental control system. Everyone enjoyed getting an inside view of this very successful nursery, which is in our own backyard!
At the end of winter quarter, students had the opportunity to sharpen their pruning skills by taking on one last project in the school arboretum. Each chose a plant to work on and took care of some early spring clean-up. Whether it was getting rid of dead, diseased or damaged wood, or formative shaping, the class helped to make the arboretum a more beautiful place. Good work everyone!
During the last week of October an exciting project took place in the arboretum. In conjunction with Cascade Water Alliance our Environmental Horticulture class installed an irrigation system in parts of the arboretum, covering the perennial beds, the native plant beds, the grass bed as well as the back lawn. With a group of highly organized experts in the field, headed by Mike Brent, our students learned about layout and design as they dug trenches in the rain throughout the arboretum. The irrigation components were all donated from two major suppliers, Rainbird and Hunter. We received a wide variety of fittings, heads and two separate control systems which will demonstrate the options available. This newly designed irrigation system is meant to become a learning lab in the future. The plan is for horticulture students, as well as outside groups, to come in and learn about an efficient irrigation system as they are exposed to an assortment of components, including a drip system. A special thanks to the dedicated team of Mike Brent, Water Resources Manager at CWA, Michael Laurie, Howard Stenn, Dave McGrath and Carrie from Seattle Tilth for making this all possible.
This summer we are carefully growing on many of the plants we had at our spring plant sale. These make up our stock plant collection from which we will take cuttings and propagate new plants for the 2015 sale. It's amazing that from a only a handful of bacopa plants we will create thousands of individual plants to sell in the spring. Because these few plants will turn into so many, we're watching them carefully. Tending them, pinching them, watering and fertilizing them.
Aphids continue to be problematic so we are still using beneficial insects as a biocontrol. Sound Horticulture is supplying us with several ravenous predatory insects. One of them is the green lacewing or Chrysoperia rufilabris. The eggs of the lacewings arrive stuck to little black tabs. They hatch quickly and the larvae are hungry! During their two to three week larval phase the lacewings can eat over 200 pests a week, earning them their nickname of aphid lion. The lacewing larvae is a versatile little biocontrol in greenhouses, field crops and orchards. Besides aphids it preys on thrips, spider mites, sweet potato and greenhouse whitefly, mealybugs, leafhoppers and the eggs and caterpillars of moths. After the larval stage the adults will live four to six weeks, feeding on nectar, pollen and honeydew. Females can lay up to 200 eggs attached to the top of a hair-like filament on the leaves and the cycle begins again.
In addition to our aphid lions, we are using other beneficial insects and also a microbial insecticide. Stratiolaelaps and Amblyseius cucumeris are both both predatory mites and they seem to be doing a great job of keeping thrips under control. The insecticide we are trying is Preferal. It's a naturally occurring fungus which infects many insect and mite pests on foliage and in the soil. The spores attach and penetrate the pests, eventually killing them. The Preferal seems to be working, although we can't seem to completely get rid of those aphids. Whether they are escaping in little hidden crevices or new aphids are constantly flying in, they really like the environmental horticulture program this year. One negative to using the Preferal is the cost. $130 for a 1 pound bag, which is only viable for one month after it's opened. So as we continue to grow our stock plants this summer, we will also continue learning new methods of care and control. That's what keeps life interesting!
Our spring field trip to the Elisabeth C. Miller Garden in Seattle was unforgettable. We spent an hour on a guided tour of this truly remarkable garden. To learn more about the garden, visit millergarden.org.
Normally growing aphids is a bad thing, but in respect to our beneficial insect program, it's a good thing. Here in the Environmental Horticulture Program at LWIT we grow and propagate thousands of plants in our greenhouses. Each year the students put on a huge plant sale that generates money that helps fund the program. This year we had a serious threat from aphids, which began appearing in November and stayed through the spring. Working with Alison Kutz from Sound Horticulture, we began a biological control program, using beneficial insects. We started to bring in good bugs to help us wipe out the bad bugs.
One of the insects that parasitizes aphids is the native wasp Aphidius matricariae. It seeks out aphids and lays an egg inside them, killing the aphid and producing another generation of wasp. Each female lays about 100 eggs, but may attack 200-300 aphids in the process. That's a lot of destruction from one tiny super-wasp. The larvae develop entirely inside of the aphid which turn a light brown and remain on the leaf surface. These aphid shells are referred to as 'mummies'. They aren't just found in greenhouses, I recently discovered an aphid mummy on my Japanese Maple. I was happy that nature was helping me keep my plants healthy.
Buying Aphidius frequently, however, can get expensive, so we decided to raise our own. A true baby wasp nursery in the greenhouse. It's called the banker plant system. We raised a type of aphid that only lives on grasses, so it wouldn't transfer to our greenhouse crops, and this provided a place for Aphidius to maintain and grow their populations. More wasps, less aphids...healthier plants. We had to build an exclusion cage to keep Aphidius out until the aphid populations were strong enough. We sprouted our wheat plants and left them in the exclusion cage for 2-3 weeks and them placed them on benches around the greenhouse. It was fascinating to watch the Aphidius we released near these plants. We could actually see them attacking the aphids, not a good viewing activity for the faint of heart. This is parasitism at its best. As our wheat matured we noticed more and more aphid mummies appearing on the plants. The system appeared to be working! Our aphid numbers did get too high at times and we still had to spray with insecticidal soap. Next year we will start our wheat earlier and get a strong population of Aphidius ready to engage in battle.
Written by Elaine Sawyer, May 2014