Starting and growing transplants under lights Curtis Swift, Ph.D. Colorado State University Extension
What it is? • Definition – transplanting is the shifting of plants from one place or growing medium to another • Goal is to produce vigorous plants ready to be planted in the garden
Why use transplants • Avoid problems of seed emerging through soil crusts of clay soils • You can more closely control depth of planting • Seeds germinate under ideal conditions • Extends the growing season • Earlier harvest is more attainable by using transplants than by direct seeding in the field
Not All Vegetables Transplant Well • Plants difficult or not to transplant include: • Root crops (carrots, beets) • Leafy biennial herbs (dill) • Heading types of Chinese cabbage • Cucurbits (cucumbers, pumpkins, squash) • Do not like their root systems disturbed • Vegetables growing quickly when seeded in the garden (radish, leaf lettuce, spinach) • Transplanting is not worth the effort
Vegetables Traditionally Transplanted • Small seed vegetables • Tomatoes, peppers, head lettuce, broccoli • Some vegetables are traditionally started from transplants because they do not produce seed or the seed lacks vigor • Sweet potato, Irish potato
Commercially Grown Transplants Advantages • They are easy • Inexpensive if you only need a few plants • They do not require that you commit time and money • Better (ideal?) growing conditions and care
Commercially Grown Transplants Disadvantages • It can be difficult to find “good quality transplants” • You may not be able to find transplants of a specific cultivar • The transplants may introduce diseases, insects, and weeds into your garden
Age affects production • Smaller, stocky plants that have not started to bloom and/or set fruit will adapt to the garden more easily than leggy transplants that already have small fruits hanging on them. • Tomato plants 4-5 weeks old grow and yield better than older transplants. Best Size – 6 “ tall and 6” wide
Producing Your Own Transplants • Advantages • Can ensure disease-free transplants • Transplants available when needed • Best use of expensive seed • Produces transplants you desire • Gives you a good feeling
Producing your own Transplants • Problems • Low light, excessive nitrogen, and high temperature cause excessive stem elongation • Damping off disease
Producing Your Own Transplants • Important factors determining your success • Growing media • Environmental conditions • Light • Temperature • Moisture
Producing Your Own Transplants Growing Media • Want to use a soil-less growing media that does not contain soil from your garden or yard • Why not use garden soil? • Tends to be poorly drained and subject to water logging • Contains insect pests, diseases, and weed seed
Producing Your Own Transplants Growing Media • Characteristics of a good soil-less growing media • Free of pests • Good water-holding capacity • Well aerated and drained • Low in soluble salts
Producing Your Own Transplants Growing Media • Common components of a soil-less growing media • Peat moss • Provides the base for most soil-less media • Decayed remains of sphagnum moss • Vermiculite • Mica-like material that has been heated to a high temperatures • Provides pore space and retains moisture and nutrients • Perlite • An inert light weight volcanic material
Planting • Plant seeds at a depth of 3 times their diameter • Broadcast very small seeds such as broccoli or lettuce and cover with a light sifting of soil
Producing Your Own Transplants Light • Factor most likely to be limiting for good quality transplants • Interrelated with temperature and moisture • Inadequate light often leads to cold temperatures and too much growth • Too little light causes weak spindly plants susceptible to falling over • Vegetable transplants need more light than standard houseplants
Light • Plants grown in the dark are yellow (chlorotic), taller (etiolated), have thinner stems, and in general, are not so healthy • ultra-violet (below 400 nm) • visible (approximately 400-700 nm) • far-red (approximately 700-800 nm).
Producing Your Own Transplants Light • exposure to red light increases seed germination, reduces seedling stem elongation, and promotes lateral shoot growth of many species • an increase in red light and/or a reduction in far-red light in the greenhouse can be used to reduce plant height. • Plastic sheeting that reduces far-red light is available and have been used to produce healthier plants.
Fluorescent Lights • on for 12 to 16 hours per day • no more than 4 inches above the tops of the seedlings • One cool-white plus one warm-white tube • Or • Use Full Spectrum Grow Lights high in red light relative to far-red light, produces short & compact plants.
Fluorescent • High Pressure Sodium • ~$90 • Expensive • Very effective
Incandescent Lights • On for 12 – 16 hours per day • 1 to 3 feet from top of plants • Spot Grow ~$30 • Has proper plant growth enhancing light • Limited space receives light • Regular Incandescent bulb • Due to high level far-red light relative to red light, frequently lead to stem elongation.
Red vs. Far Red Light • Controlling the red to far red light ratio is a means of controlling seedling height without reducing fruit yield or quality • Incandescent lamps, which are low in R:FR ratio, frequently lead to stem elongation while fluorescent sources, which are high in R:FR ratio, produce short and compact plants.
Producing Your Own Transplants Temperature • In windows there can often be large temperature fluctuations between day and night or sunny and cloudy days • Cooler than optimum temperatures may: • Increase disease • Cause rough fruit in tomatoes • Cause bolting in onions • Warmer than optimum temperature may cause weak spindly seedlings
Root Zone Heating • Root zone heating is another method to stimulate quick germination • Use a heating pad
Tomato and PepperAir Temperature • Start seeds at 65 - 75 degrees F.After emergence, lower temperature to 60 - 65 degrees F. • Day temperature can be about 10 degrees warmer than night temperature. • Do not allow to get too hot • 75 - 80 degrees F. is too hot • Too high a temperature will result in leggy plants.
Cabbage, Broccoli, and Cauliflower Air Temperature • Seeds should be started at 55 - 60 degrees F. • After emergence: • Day 65F • Night 55 F
Producing Your Own Transplants Moisture • Avoid cool temperatures and dark conditions • Reduces transpiration and increases excess water problems • Too much water is associated with diseases which require moisture • Examples: root rot and leaf spot fungi
Water • Moisture • Ways to avoid problems with diseases fostered by too much water • Thoroughly water when seed • After emergence water in the morning so leaves will be dry before night and spot water only the dry places • Too little water rapidly kills young seedlings
If reusing trays or flats • wash to remove any soil or plug media that may adhere to the plastic • dip in a 10% solution of chlorine bleach • 9 parts water to 1 part bleach • rinse trays thoroughly before they are reused
Fertilizer • Seedlings will need to be fertilized as soon as they emerge. • Avoid fertilizers with a high concentration of urea. • Over fertilizing can injure seedlings or promote damping-off disease. • Fertilize two to three times per week with the liquid solution.
Fertilizer • Tomatoes are very responsive to fertilizer and excess fertility will reduce transplant quality. • At every watering use a fertilizer concentration of 50 to 100 ppm Nitrogen • Or once every seven days - use a concentration of 250 to 350 ppm Nitrogen
Fertilizer • Peppers require more fertilizer than tomatoes • If feeding at every watering, use approximately 100 PPM Nitrogen • Increase the concentration if feeding less often.
Vining Crops • Two to four applications of fertilizer at weekly intervals, at a 100 to 150 PPM Nitrogen concentration, should be sufficient to produce good-quality vine crop transplants.
Determining ppm NLiquid Products • You need to know ppm N of the product • May be ppm on the label • May be given as percentage • If percentage • Base ppm on one gallon • One gallon is 3,780 milliliters (ml) • Round off to 3,800 ml
Determining ppm NLiquid Product • i.e. 10% is 100,000 ppm • i.e. 12% is 120,000 ppm • i.e. 15% is 150,000 ppm • Need to dilute to appropriate ppm for final fertilizer solution
Determining ppm Ci x Vi = Cf x Vf i = initial f = final C = ppm V = volume in milliliter 1 gallon = 3,800 ml; 1 quart = 950 ml 1 pint = 475 ml; 1 cup = 240 ml
Determining ppm Ci x Vi = Cf x Vf If using a 12% N product (120,000 ppm) and want a 100 ppm final solution: (120,000 ppm)(Volume in ml) = (100 ppm)(3,800 ml) = ml of product to add to sufficient water to make a gallon of fertilizer with 100 ppm of Nitrogen 1 gallon = 3,800 ml; 1 quart = 950 ml 1 pint = 475 ml; 1 cup = 240 ml
Determining ppmfor 100 ppm solution Ci x Vi = Cf x Vf ml to add to water to make one gallon of a 100 ppm N fertilizer solution 10% 100,000 ppm use 3.8 ml 12% 120,00 ppm use 3.2 ml 15% 150,000 ppm use 2.5 ml 20% 200,000 ppm use 1.9 ml
Determing ppm of dry fertilizer • Add equal amounts of fertilizer to water • Add water first • Add fertilizer to double the amount in the container • The resulting solution is one-half the % on the label of the dry product • i.e. 20% N is not 10% nitrogen • Do computations using Ci x Vi = Cf x Vf
Hardening-off Transplants • Definition: Hardening-off is the process whereby transplants stop growth and develop greater tolerance to the weather so they can survive being planted into the garden • Is critical for both commercially grown transplants and transplants that you grow on your own
Hardening-off Transplants • Hardening-off causes: • A slowing of growth • Greater cuticle thickness and waxes on leaves • Build-up of sugars • Ways to harden-off transplants • Only water the transplants when they start wilting • Stop fertilizing • Expose transplants to cool temperatures and/or higher levels of sunlight
Contacts • http://WesternSlopeGardening.org • Curtis.Swift@colostate.edu