Nebraska Extension Horticulture Column for May 1, 2022 Garden Transplants

Start Your Garden Right with Healthy Transplants 

Transplants are the way to go with tomatoes, peppers and dozens of other vegetables, as well as many of the annual flowers common in Nebraska gardens. Transplants give long-season crops a head start before being put out in the garden and a chance to produce before fall frost. Annual flowers grown from transplants begin blooming weeks earlier than they would if a gardener planted them from seed. 

Tips for Success

The first key to success with transplants is selecting healthy young plants and handling them properly. Transplants should be stocky and compact with healthy-looking foliage. Green foliage should be a rich dark green, not pale or yellow, and free of spots that might indicate disease. Check the undersides of leaves for signs of insects.  

Colored foliage - as on coleus, for instance - should be free of discoloration or signs of disease. Wilted foliage may mean the plant needs water, but it can also be a sign of root rot or other disease problems which you don’t want to bring into your garden! 

Though it's nice to see annuals or perennials in flower, the best transplants are those without flowers or fruits. Right after planting, transplants need to concentrate on establishing a large, strong root system. If they've already switched from vegetative growth to flower or fruit production, they may be able to do this as readily and may struggle through the season with an inadequate root system. 

Avoid extremely large transplants. They often suffer more transplant shock when finally planted in the home garden and grow very slowly or bolt (flower prematurely), or even die.  

 Hardening Off

The shock of going directly from a sheltered greenhouse environment to the garden can stop plants' growth or even kill them. Easing transplants into the garden in stages gives them a chance to get accustomed to outdoor conditions gradually.  

Start by setting flats outdoors in a protected area for a few hours on warm, sunny days and decrease watering somewhat. Increase the time that plants spend outside each day for several days. This process, called hardening, reduces the amount of transplant shock the plants suffer when they're set in the garden. 

Plants purchased from an outdoor table at your local garden center are probably already hardened off, which saves you time and effort.  

 Transplanting

At transplanting time, handle plants carefully to avoid damaging their roots and stems. All plants should be removed from their growing container before planting, even if this was a peat pot. If the peat pot absolutely cannot be removed, then soak it thoroughly before planting and make sure when planted the pot edge is completely covered by soil. If the pot’s lip is left exposed, it will wick water away from the transplant's roots. 

Plants in multi-compartment containers should be well-watered before planting and removed from their cells with care. If plant roots are heavily encircling the edge of the rootball, the plant is root-bound or pot-bound. Pull off the very bottom section of the rootball and gently spread the roots out. The goal is to encourage the roots to develop more growth and not continue to grow in a tightly compressed circle, which could stunt plant growth.   

Get plants quickly into the garden soil so their roots don't have a chance to dry out. All transplants should be watered in after transplanting so dry soil around them doesn't pull water away from their roots. 

 Early Season Care

Often it isn't enough to just stick the plants in the ground and water -- newly set transplants may need protection against insects, frost and wind. 

All transplants are subject to wind damage. Commercial plant covers or caps, windbreaks of evergreen prunings and milk jugs with the bottoms cut out can be used to keep wind from flattening newly set transplants. 

 Even the healthiest transplants with the best handling will experience some root damage at transplanting. Until they get their roots established, the tops won't grow. To promote good transplant recover and growth, give plants a dose of fertilizer at transplanting. Dissolve 1 to 2 tablespoons of a general-purpose fertilizer, such as 10-10-10, in 1 gallon of water. Give each plant 1 to 2 cups of the starter fertilizer to help get them off to a good start.  

Cutworms are hairless caterpillars that snip off seedlings and transplants at or just below the soil surface. They're especially fond of pepper plants, though they may damage other plants, too. A 3- to 4-inch-wide strip of lightweight cardboard formed into a circle and pushed into the soil around each plant is usually all that's necessary to protect it. 

 Cold Temperature Protection

The average last frost for Lancaster County usually occurs between April 29 and May 12 - check your average last frost date, https://go.unl.edu/springfrost.  

Basing garden planting dates on soil temperatures, is a good way to get your plants off to a good start. Cool-weather crops such as broccoli, cabbage and other members of the cabbage family will tolerate cooler soil and air temperatures and even some light frost and so can be planted earlier. Check your soil temperature, including the daily reading and a weekly average from Nebraska State Climate office, https://cropwatch.unl.edu/soiltemperature.  

 Frost protection may be needed if warm-weather crops such as tomatoes and peppers are planted early or frost threatens after the usual frost-free date. Warm-weather crops shouldn't be planted until the soil has warmed up to 65 degrees and the average date of the last frost is past. They usually grow poorly, if at all, before that, so little is gained and the plants might be lost if they're planted too early. 

Warming the soil with plastic mulch and protecting tender crops with milk jugs or commercial plant covers can extend the season and enable warm-weather crops to go into the garden before the frost-free date. Each gardener needs to balance the time, effort and expense involved against the desire to have the first red tomato on the block and make his or her decision accordingly. 

Your Suggestions are Welcome!

Is there a lawn and gardening topic you would like to learn more about? Sarah Browning is an Extension Educator with Nebraska Extension and can be contacted by phone 402 441-7180, by mail at 444 Cherrycreek Road, Lincoln, NE 68528: or by e-mail sarah.browning@unl.edu.  

Images 1-3 by Sarah Browning, Nebraska Extension. 

  1. Healthy plants should be short and stocky, with dark green leaves. 
  2. Transplants with many roots circling the outer edge of the root-ball are pot-bound or root-bound. 
  3. Gently remove the base of a pot-bound plant's rootball and spread the roots before planting. 
  4. Header image - It's Gardening Season! Image from Pixabay.com.