Are the vegetable transplants you grow always leggy, scrawny, and dull in color? Don't you wish you could grow thick, bushy, dark green transplants instead? You can. It is simple, as long as you follow a few simple rules.
The first rule is not to start your transplants too early. I covered this in last week's column but for those of you who missed that column, I'd suggest you check out the information on growing transplants on my blog at Swiftsgardeningblog.blogspot.com or drop me an email or give me a call and I'll mail you that information. The key is to have transplants of the proper age when they are set out into their permanent spot in the garden.
A second rule is to provide your transplants adequate space to they don't crowd each other. When these young plants are crowded they stretch in order to capture more light. They develop thin stems that are more prone to breakage when crowded together. Crowding also results in the lower leaves not receiving adequate light and becoming weak and more susceptible to disease. The loss of these lower leaves also results in less food (sugar and starch) flowing to the roots where it is needed for stronger more extensive root systems.
A third rule is to ensure adequate light reaches every green cell of the transplant, leaves, stems and buds. Every green cell of the transplant produces food necessary for the health of the plant. These cells also produce hormones necessary for the development of more shoots, leaves and roots. Fluorescent lights placed over the transplants are quite effective in providing sufficient light to all of these green cells if they are close enough. Fluorescents should be placed 4 inches from the top of the plant. As the plants grow, these lights need to be raised to keep up with the plants' growth.
If incandescent lights are used, due to the heat they generate, they must be the type that reflects heat away from the plants. Even then, incandescent lights should be between 1 and 3 feet from the top of the plants. LED lights are becoming more common but are still extremely expensive for most of us. The two-tube fluorescent light fixture I use for demonstration purposes has a warm white and cool white tube. You could purchase the more expensive plant-growth tubes but they are not always available. Lights should be put on a timer so they are on from 14 to 16 hours.
Keeping the plants hydrated and provided with the proper nutrients is necessary. Many of the planting mixes available for the production of transplants are supplemented with fertilizers. Those fertilizers, especially nitrogen, are gradually depleted as the transplants grow and needs to be replenished. Most growers start to fertilize their seedlings as soon as they emerge from their seeds. Fertilizing two or three times a week is not unusual. The amount of nitrogen these young transplants require differs with the type of plant.
For example, tomatoes can be fertilized once a week or fertilized at each watering as long as a diluted solution of fertilizer is applied. This diluted solution needs to consist of between 50 and 100 parts per million of nitrogen. Peppers would like 100 parts per million of nitrogen at each watering while cabbage, cauliflower and broccoli transplants would like to be fertilized once a week with 150 parts per million of nitrogen.
Figuring out how to mix up a solution of 50, 100 or 150 parts per million of nitrogen is actually quite easy. The procedure is detailed in my publication on starting transplants under lights you will find on my blog.-
Dr. Curtis E. Swift is a retired horticulture agent with the CSU Extension. Reach him at Curtis.Swift@alumni.colostate.edu or check out his blog at http://SwiftsGardeningBlog.blogspot.com. He owns Swift Horticultural Consulting and High Altitude Lavender.