Dr. Jerry Parsons, Extension Horticulturist (Vegetables)
Texas AgriLife Extension Service

This is a transient society we live in. People are changing jobs, moving from one town to the next and many times leaving those that they love the most–their plants. Loss of one’s loved ones–the plants–can be a traumatic experience and one which is not really necessary. If you are a mobile person, why not keep your plants portable too? Porta-growing is the answer! Grow your plants in containers. Even if you’re not the rambling kind, keeping plants moveable can offer certain advantages. The mobility of porta-plants allows you to move them to protected areas during periods of adverse weather. Such protection enables production during the normal off-season for your area and allows you to grow plants which would be damaged by the cold winter temperatures without protection.

Porta-growing in containers is actually easier than perma- growing in soil. Much of the Texas soil that people try to culture plants in lacks some of the basic necessities for healthy, productive plant growth. These basic necessities include drainage, organic matter, optimum soil pH and freedom from pathogenic organisms as well as the common problems of insufficient, an imbalance of and/or an unavailability of nutrient elements. Porta-growing in containers eliminates most of the common problems involved with perma-growing in soil because culture inputs such as growing medium, location and fertilization are controllable and manageable.

Porta-growing requires a container. Suitable containers vary from wire mesh hanging baskets to bushel baskets, gallon cans, wooden boxes or even such oddities as old hats, styrofoam coolers, and discarded toilets. The best container to use is the one which fulfills your requirements of size, portability, endurance and cost. Optimum container size will vary according to the plant to be grown. Obviously a lettuce plant can be grown more successfully in a very small container than can a dwarf peach tree. The ultimate size of the plant being grown should be directly correlated with the size of container used. The size of the container, plant size, container location and the choice of soilless mix will determine the frequency of watering and intensity of cultural management. Obviously, a larger container with a greater quantity of potting mix will retain more water, fertilizer elements, etc. than a smaller container. However, the larger the container, the less portable.

Regardless of the container chosen, adequate drainage is a key to success. A soilless mix which drains rapidly should be used. Ideally, when you pour water around the base of a porta- plant, water should soon be coming out of the bottom of the container. This not only indicates proper drainage but also enables leaching of fertilizer salts which, if accumulated, can damage a plant’s roots. Soilless mixes should be soilless– absolutely no soil! Regardless of how wonderful you think your soil is, when soil is put in a container it loses many of its beneficial qualities. Soil in a container compacts which causes poor drainage and insufficient aeration. Microorganisms such as nematodes and pathogenic fungi may also contaminate the root system of the porta-plant if non-pasteurized soil is used. Many suitable types of soilless mixes are commercially available. A soilless mix should be disease and weed-free, retain adequate moisture after watering yet is well-drained and lightweight. You can mix a soilless growing medium of 50 percent organic materials (one-half peat moss and one-half shredded bark), 25 percent perlite or vermiculite for drainage and aeration and 25 percent washed builder’s sand.

Once you have formulated or purchased a well-drained soilless mix in which to grow the porta-plant, be sure that the container being used has adequate drainage capabilities. If a water-tight container is being used, drainage holes will have to be drilled. A 3- to 5-gallon container should have at least four drainage holes. When considering drainage holes, the olde saying, “The more, the merrier” definitely applies. Also, don’t worry about lining the bottom of the container with course gravel or charcoal to expedite drainage. Recent research indicates that such a gradient in materials actually impedes drainage. If a loose soilless mix is used, water drainage through drain holes will not be a problem.

The taller the container, the more difficult it is to obtain even water distribution. Some people utilize whiskey barrels as containers in which to plant. The half-barrels are the easiest to grow in since plants in the bottom section of full-size barrels either don’t get enough water or drown from too much water from the top. To insure an even distribution of water throughout the container as well as reduce the amount of soilless mix needed, construct a center core of a rapid draining material. I have had success using a cylinder of concrete reinforcing wire filled with coarse bark. Soilless mix is added around the cylinder from the bottom of the barrel as transplants are placed through drilled holes in the side. Watering is always done in the center core so that plants at the top as well as the bottom have equal access to moisture.

Porta-plants require adequate fertility for vigorous growth and, if you are growing fruit and vegetables, high yields. Soilless mixes are lacking in sufficient nutrient elements for optimum plant growth. Fertility can be provided in two ways. The most common technique is to periodically water with a fertilizer solution. Commercially prepared, water-soluble formulations are available in local nurseries. Follow label directions when mixing solutions. A home-made nutrient solution can be made by dissolving two cups of a complete garden fertilizer (No weed-and-feed formulations, please!) such as 10- 20-10, 12-24-12 or 8-16-8 in one gallon of warm water. This solution will be your base solution. From this base solution you will prepare the porta-plant nutrient solution. To make the actual nutrient solution with which to water, mix two tablespoons of the base solution into one gallon of water. Never sprinkle granular fertilizer in porta-plant containers; plant damage can occur.

Fertilization requirements differ according to the type of plant being grown, soilless medium used and growing location. For instance, most people do not want houseplants and foliage plants to produce excessive growth, so low maintenance levels of fertility should be used. Conversely, successful production of fruit trees and vegetable crops depends on rapid, continuous growth and plant vigor so high levels of fertility must be maintained if quality production is expected. Lettuce is a good example; if lettuce is not grown with high levels of fertility available, the leaves produced will be extremely bitter. For the latter group of high-maintenance-fertility plants, I recommend the use of slow-release fertilizer pellets mixed into the soilless medium at planting time or applied around an established plant. This is in addition to the use of water-soluble fertilizer several times weekly. Use the longer release (3 month) formulations of the slow-release fertilizer pellets and follow label instructions for application or mixing. Research indicates that constant feeding (using water-soluble fertilizer) plus the addition of slow-release fertilizer produces a better plant. It seems that slow-release formulations insure that optimum nutrient elements are available during periods of potential deficiency when soilless mixes have dried after being watered with the standard nutrient solution. Slow-release fertilizer is also a good, cheap insurance against memory loss– we might forget to fertilize often enough! Also remember, porta- plants are like children–as they get larger they require more feeding. A full-grown, heavily loaded tomato plant in a container needs a water-soluble fertilization treatment daily.

Porta-plants have a mobile advantage but the disadvantage of a limited, confined root system. Because culturing plants in containers severely limits their root spread, frequent watering and fertilization are essential. As emphasized earlier, the well-drained soilless mixes–necessary for good aeration–need frequent watering. As plants grow larger, more watering is required because water is being absorbed and transpired. As temperatures increase more water is evaporated from the mix and transpired from the plant. Young porta-plants growing in cool weather may require watering only once every two or three days. Check the moisture level of the mix with your finger before watering, i.e., water the mix, not the plant. If you feel moisture with your finger DO NOT WATER; more plants are killed by overwatering than by being too dry. Larger producing plants may require watering two or three times a day. Remember, container size and soilless mix used will have a lot to do with the watering regime followed.

The same principles of success which govern perma-growing in soil apply to porta-growing in containers. If the plant’s requirement is a full-sun (8-10 hours daily) condition, a porta- plant of this type will not perform at the optimum if grown in the shade–regardless of the love and care provided. Also remember that a porta-plant can shade itself and should be rotated periodically to insure exposure of the entire plant to the full sun condition so that uniform foliage and fruit formation will occur. If a foliage plant or flowering plant such as begonia requires a partial shade growing condition, putting such a porta- planted plant in a full sun condition dooms it to failure. Follow plant tag recommendations for light requirement. Generally, those plants which produce an edible fruit such as tomato, pepper, eggplant, blackberry, peach, apple, etc., require the full-sun condition. Those plants which are grown for foliage such as herbs, leafy crops (lettuce, cabbage, greens, spinach and parsley), caladiums, coleus, etc. tolerate or require shading. Flowers have different requirements depending on the kind. Placement of porta-plant containers is also very important. Even if a plant requires a full-sun condition, afternoon shading of the intense western sun may be beneficial. Also remember the wind. Wind can be devastating. I have found that a northeastern exposure, if available, is the best because of the protection it allows from prevailing strong southern winds and hot evening sun. Protection should be provided when weather cold fronts cause northern wind gusts.

As I mentioned earlier, the same principles of success which govern perma-growing in soil apply to porta-growing in containers. If you don’t plant the best varieties of plants for your area you are doomed before you begin. The names of best- adapted plants can be obtained from experienced growers, the county Agricultural Extension agent or trustworthy nurserymen. Smaller growing or determinate varieties are best suited for porta-planting because of the limitations of container size. Many times the best plant varieties are expensive hybrids. Since fewer plants are needed for a porta-planting anyway, purchase transplants instead of seeding directly into the container. The use of transplants insures proper spacing and earliness of production. The dwarf fruit trees or regular varieties grafted onto dwarfing rootstock are excellent choices for porta-planting. Be sure to determine before purchase the maximum size of the mature plant being considered.

One should also consider only those plants which will offer maximum benefits from a limited growing space. For instance, the porta-plant grower of vegetables should consider the fact that crops such as broccoli, celery, collards, green onions, herbs, Japanese eggplant, kale, mustard, parsley, pepper, spinach, Swiss chard and tomato offer multi-harvests over a long period of time. Conversely, cabbage, cauliflower, garlic, lettuce and radishes are a one-time harvest. However, the aesthetic value of certain plants must also be recognized as well as their production potential. For instance, carrots are a one- time harvest crop but the beauty of the fern-like carrot tops make them a super ornamental porta-plant as well for several months during their growing season–even for interplanting. Likewise, the genetic dwarf fruit trees produce only one crop per year but their large green, dense foliage make them a rival of any ornamental during the non-fruitful period. Flowering plants should also be evaluated for foliage as well as bloom potential and persistence.

After selecting the best variety, you must carefully avoid over planting. Recall how large the plant will be at maturity. Balance and number of plants is especially critical in a hanging basket or a container which is to be moved regularly. Excessive weight on one side of a porta-plant caused by an increasing fruit load could be disastrous. Pruning can help. Hanging baskets pruned into a ball-shape are more attractive than baskets with vines hanging long and unrestrained. Periodic pruning encourages more side shoot growth and promotes a thicker, more attractive plant. Tall growing plants in wooden baskets, boxes or cans should also be supported. Tie the stems to stakes or enclose them in small cages of concrete reinforcing wire. The size and height of cages are determined by size and height of the container and the mature size of the plant. Such support makes the porta-plant more compact, more attractive and, most importantly, easier to move.

Other common sense cultural practices must be exercised with porta-plants, just as with perma-plants, if success is expected. The timing of plantings can make the difference between success or failure. Plant tomatoes after the temperatures of summer have become excessive and you are guaranteed failure. Plant caladiums too early in the spring and the bulbs will rot in the pot. Plant lettuce late in the spring and it will produce a flower spike surrounded by leaves as bitter as quinine.

Porta-plants will be attacked by the same insects and disease organisms that attack perma-plants. Most egg-laying insects have wings and most disease organisms are wind-blown so just because your porta-plant is hanging or mobile doesn’t mean that it can escape. Inspect plants periodically for the presence of insects feeding on foliage and fruit as well as for disease. Extension Service recommendations for fruit and vegetable pest control should be followed or a reliable nurseryman consulted. Follow label recommendations exactly as to control techniques including rates and timing of sprays.

Porta-plants are completely dependent on the grower for correct amounts of water and nutrients. A perma-plant in the soil can be neglected for several weeks and Mother Nature’s water and nutrients will probably carry the plant through. The porta- plant is a different story–neglect the plant for even a day and you can kiss it goodbye. It will die! But because of this life- or-death bondage between grower and plant, because of this daily interaction, the porta-plant becomes the most precious, loved plant of all. All of the work and worry culminates as you harvest that first juicy peach, crunch that first red apple or bite into the first, red-ripe tomato of the season. When you do, you know, without a doubt, that you grew this–it would not exist without your love and determination. Porta-plants forever!!!!!

FOR MORE INFORMATION, go to :
http://aggie-horticulture.tamu.edu/extension/container/container.html

 

For more information on this topic:

• The Bexar County Master Gardener Hotline
  Speak to one of our volunteer Master Gardeners on duty, 210 631-0400, E-mail at info@bexarmg.org
• David Rodriguez – County Extension Agent-Horticulture, 210 631-0400,  E-mail at dhrodriguez@ag.tamu.edu