Starting and growing transplants under lights

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Starting and growing transplants under lights

• Curtis Swift, Ph.D.
• Colorado State University Extension

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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

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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

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Ease of Transplants
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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

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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

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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

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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

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Too Leggy
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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
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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

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Producing your own Transplants

• Problems
• Low light, excessive nitrogen, and high
  temperature cause excessive stem elongation
• Damping off disease

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Producing Your Own Transplants

• Important factors determining your success
• Growing media
• Environmental conditions
• Light
• Temperature
• Moisture

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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

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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

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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

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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

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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

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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).

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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.

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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.
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Fluorescent

• High Pressure Sodium
• 90
• Expensive
• Very effective

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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.

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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 RFR ratio,
  frequently lead to stem elongation while
  fluorescent sources, which are high in RFR
  ratio, produce short and compact plants.

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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

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Root Zone Heating

• Root zone heating is another method to stimulate
  quick germination
• Use a heating pad

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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.

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Cabbage, Broccoli, and Cauliflower Air Temperature

• Seeds should be started at 55 - 60 degrees F.
• After emergence
• Day 65F
• Night 55 F

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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

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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

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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

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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.

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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

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Fertilizer

• Peppers require more fertilizer than tomatoes
• If feeding at every watering, use approximately
  100 PPM Nitrogen
• Increase the concentration if feeding less often.

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• One application per week of 100 to 150 PPM
  Nitrogen should be sufficient

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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.

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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

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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

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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
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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
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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

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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

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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

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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

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Contacts

• http//WesternSlopeGardening.org
• Curtis.Swift_at_colostate.edu