RECEIVING AND INITIAL CULTURE FOR "A" SIZE PLUGS
We would like to pass on what seems to have worked well in our experience as growers receiving plants, and what we've learned from others.
Given these "in box" conditions, it is prudent to treat your plants on arrival with a thorough shower of cool water. Water the plants generously and vigorously on all surfaces to wash off any microbes that may be present. This doesn't get them all, but it does reduce the numbers. After your plants have been washed, they can be laid out to dry if they are not going to be immediately potted. If they are not going to be potted for a few days, we would water them a couple of times a day to insure hydration. We wouldn't water them at the end of the day if the night time temperatures drop significantly.
Potting is always nursery specific and in some locations a smaller pot is preferred to what is described here. The best results we've seen with our plants have been by local (Hawaii) growers. They take our typical "A" plug and put it, foam cube and all, in a 4-inch (diagonal, 3.25 sq.) pot. They use a rather loose media which consists of 25% washed coconut chips, 25% high quality, long fiber or chunky peat, and 50% #3 perlite.
The spacing for an average size plant is five per square foot or less. Some larger plants may need more room and the more petite a little less. Some growers are bringing our plugs to spike and bud in under a year. With these results, this culture is worth trying.
The light levels we have suggested for specific plants are based on what we've seen in typical mainland nurseries. Light and temperature are always tied together. If light levels are lower, ambient temperatures can be higher. If ambient temperatures are cooler, light levels can be higher. Here in Hawaii we've seen very robust and vigorous our plants grown under 60% shade cloth with open sides which is about 4,000+ foot candles. We wouldn't think of trying this under greenhouse conditions in Southern California or Florida in a typical closed greenhouse.
After trying a lot of different fertilizers, making many errors, reading several books on plant nutrition, and a couple of dozen articles on fertilizers and nutrition we think we have it, again. We fertigate two to three times per week depending on weather conditions with 125 ppm of nitrogen in a balanced fertilizer (something like 12-4-8-5-1, N-P-K-Ca-Mg) spring and fall, this can be increased in the long day summer months to 150 ppm of nitrogen. For those of you who don't mix your own fertilizers and consequently can't mix up the exact ratio above, there is a simple way to get there with three types of bagged fertilizer. Scott's makes 15-5-15 Cal Mag Special, 15.5-0-0 Calcium Nitrate (water soluble) and 20-10-20 Peat Lite Special. When using the 15-5-15, add 5 pounds of the Calcium Nitrate (15.5-0-0) to every 25 pound bag. This brings the ratio of Calcium and Magnesium to 5:1. All of these fertilizers are primarily nitrate forms of nitrogen. This will keep your spikes and plants a little shorter and make the cell walls sturdy and less prone to infection from bacteria and fungi. In the winter you can reduce the fertilizer to 100 ppm of nitrogen. This will save you a few bucks and the extra fertilizer won't make the plants grow any faster. If you have two injection heads these fertilizers can be used together. If not, you can alternate. We alternate between 20-10-20 and the 15-5-15 + calcium nitrate, two times each then on to clear water once, and start over again. The clear water prevents pH shift in the media and helps with salt build up if you are not keeping the media damp.
We have been too many nurseries and seen damaged leaves. Leaves that have scalloped margins and a while where the scallop edge dives in. This is caused by excessive chemicals or chemicals that are not compatible and have a toxic effect on the very new and tender foliage. When spraying to run off it is inevitable to get the crotch of the new growth wet to overflowing. As the water evaporates the concentrations of chemicals are increased dramatically and this causes this scalloped effect.
Another cause for the scalloped effect is too much surfactant. This can be alcohol based or silicone based surfactant. If the concentration is too high the new tissue in the crotch of the new growth will be damaged. The recommended rate for surfactants seems to be determined by the poor water quality in areas like Florida and California. I find that 10% of the recommended quantity is sufficient for all our sprays. We do have excellent water quality and consequently need little surfactant.
I suggest a test to determine the quantity needed for each chemical or combination of chemicals you use. Here is our test; we mix the chemical and put in the least amount of surfactant we think will be effective. Then we take several different types of plants being sprayed and dip them in the chemical and see if the spray materials bead up or lay flat. We like our chemicals to not bead up and have just a few rivulet. This suggest that we will have good coverage, no chemical spots after drying and we won't have surfactant burns causing scalloping of the leaves.
Your questions and comments are always welcome. Warm aloha and good growing to you from all the staff at The OrchidWorks.