APRIL IN YOUR ORCHID COLLECTION
APRIL CLIMATE DATA
Average high: 83.8
Average low: 67.6
Average mean: 75.7
Average rainfall: 3.36"
Far from the cruelest, April is the kindest month to South Florida orchid growers. The weather in April is definitely settled into warm, even deliciously hot, with passing cold fronts only adding the delight of a pleasant change in temperature. The clean, bright days brimming with abundant sunlight and the low relative humidity create the high drying potential that orchids love. Now we can get our orchids off to a great start on the growing season by practicing our very best watering skills under ideal conditions. Water heavily when you water and allow the plants to dry thoroughly before watering heavily again. Drying 'hard' in the spring will produce benefits all season. We want to get our plants well launched while leaving all the fungi high and dry.
The new shoots of Oncidinae, grammatophyllums and dendrobiums forming now are quite cup-like; care must be taken that water does not stand too long in these immature growths. Water these types very thoroughly with two or three applications of water spaced 10-15 minutes apart. Water should run freely through the pot on each application. Saturated thoroughly in this fashion the plants will need only weekly watering. Even more care should be taken with the soft plicate leafed genera like Catasetum, Mormodes, Cycnoches, Gongora, Calanthe and Thunia The new growths of this type are rolled together (the fancy word is convolute) like a collapsible drinking cup. These should be grown in water retentive media that should be saturated at each watering to permit the developing roots to have abundant water but allow the vulnerable new growth extra time to dry. Feel the weight of a pot when you have finished watering. Be sure it is heavy with water. If it's not, water one more time. With plants properly spaced, good drying should not be difficult in the hot dry air of April. But do be careful to water early enough in the day to allow the tender new growth to thoroughly dry by twilight.
With vandaceous orchids grown in slatted baskets, most growers find that they dry altogether too well in April. Vandas can be watered almost every morning in April. Indeed, a second light watering or misting in mid-afternoon in April and early May is often beneficial provided the crowns and leaf axils of the plants have time to dry completely by nightfall. Another strategy under high drying conditions is to bend the rules, at least occasionally, and water heavily in mid to late morning. Late waterings on weekend mornings (you didn't want to get up early, any way) provide relief for plants that are more stressed on week days with their owners absent. Very occasionally, one needs to break the rules absolutely and water thoroughly (not just mist) in the mid to late afternoon so the plants can slowly absorb the water across the cool hours of the night. This is the season that one must be sure that Vanda roots have turned overall dark green when we have finished watering. Two applications of water to the point of runoff spaced several minutes apart should accomplish the required color change from white to totally green. Saturated roots are absolutely necessary to provide the plants the moisture the plants need to withstand the heat and dry air typical of April. Sometimes, particularly at this season, the roots will not change color even after the second or third application of water. This lack of response to water is because the roots have become so dry that they are repelling rather than absorbing water. They are behaving like a cork in a wine bottle. The grower must exert special effort to re-saturate the roots. Often this will require 4 or 5 waterings to the point of run off spaced 15 minutes apart. Once the roots have been changed to the healthy overall green, normal applications of water should bring them around in future.
With increased heat and light and the onset of growth, fertilizer becomes more crucially important to the plants. Balanced time release pellets (13-13-13) can still be applied to potted plants provided the duration is 180 days or less. Most time release fertilizer breaks down faster under South Florida conditions and should be exhausted by October when we will want our plants to slow down. The brand marketed at retail as "Dynamite" is generally considered by professionals as superior in reliability to other types. In April, 15-5-15 can be applied to most genera at the rate of 2 tsp. per gal every two weeks. Vandas, ascocendas, Aerides, et al will benefit from a full tablespoon of 15-5-15 weekly during this high energy period. One can also apply high phosphorous 'Bloom Booster' fertilizer once or twice at this time to stimulate them to flower for Mothers' Day or failing that to win those trophies and AOS awards at the Redland International Orchid Festival the next weekend. High phosphorous (we use Millers' Solugrow 8-48-12) also stimulates root action and is important in getting all genera off to a good start on the growing season. This is one of the few times that high phosphorus is perhaps beneficial. During the rest of the year it is to be avoided particularly with our alkaline water. Current science recommends fertilizers lower in nitrogen, much lower in phosphorus and higher in potassium, magnesium and calcium. Peter's Excel 15-5-15 is now the standard for year round use.
The warmth of April, alas, stimulates the growth of bugs as well as plants. Both Thrips and mites thrive in the dry heat of April. Liquid dishwashing soap (at 2 oz per gal) will control both but be mindful that soap should not be applied to plants that are suffering from drought stress. Be sure that your plants are well hydrated before you apply soap. Water them extra hard the day before. To be effective soap must be used profusely. The plants should be washed in the solution to the point of wetting every nook and cranny of both the plant and its container. Only such thorough treatment can reach the reclusive Thrips and be sure to touch all of the ever prolific mites. A second treatment at 7-10 days is necessary to control mites and a miticide such as Kelthane might be advised. Orthene which is the insecticide of choice for Thrips (because of its residual action) is compatible with many miticides. Check with your county agent if in doubt.
April is the classic month to catch up with all the re-potting which you meant to do across the winter. New roots form fast in April; don't rot them off by over-potting or break them off by allowing the plant to wiggle in the pot. Tie them up: tie them down!
April is a month for great moral decisions. When turning on the air conditioner for the first time, consider how much better an orchid grower you would be if you set the thermostat 2 or 3 degrees higher. You will find that you spend more time with your plants when you are accustomed to slightly higher temperatures and it is the master's shadow that makes the plants grow. Besides spending more time enjoying your orchids, when the FPL bill arrives, you can celebrate with some splendid additions to your collection.
April is a great month for naturalizing orchids in the garden. Perhaps it's time to think of new homes for some of our burgeoning collection on trees or elsewhere. The space emptied in the growing area will soon fill with the healthy new growth of those plants which remain to enjoy their additional light and air.