Amazing Technicolor Heirlooms
Tomatoes are a crop which has a huge diversity of fruit shape, size, color and flavor - from tiny yellow pears to giant purple-black beefsteaks or long green cylinders - the selection seems endless. While it is the medium-sized, round red hybrids which have long dominated the hydroponic industry, over the last few years heirlooms have begun to make a comeback in commercial tomato production.
This trend was probably started by backyard tomato connoisseurs who hankered after the open-pollinated types of yesteryear and began their own small scale production. However heirloom tomatoes have become one of the most rapidly expanding specialty or niche hydroponic crops - albeit one that requires a high degree of skill and plant husbandry to produce well. While the modern greenhouse hybrid cultivars still dominate the tomato market, heirlooms have quietly increased in volumn and variety.
Despite many heirlooms being well over a century old, larger-scale commercial production using hydroponic technology is relatively new.Many factors have lead to a demand for these older tomato types such as a surge in farmers markets, growing consumer interest in ethnic and specialty crops, an emphasis on selling organic produce and an increasing number of gourmet chefs looking for flavor diversity. Heirloom tomato cultivars can offer a range of diversity that standard round red commercial hybrids can not. This combined with the consumer perception that heirlooms taste better than modern hybrids and have more character due to their interesting names and nostalgic background, has seen this niche market expand at a rapid rate. The colorful history and background of many common heirloom varieties is a successful marketing strategy used by many growers to promote their fruit as superior to modern hybrids and to get a high return on their crops.
Generally it has been the smaller hydroponic growers who have targeted the heirloom niche market, aiming for direct sales to consumers and restaurants through farmers markets or other local outlets. Many heirloom varieties do not ship or handle well due to thinness of the skin which splits and damages easily. Smaller growers selling directly can provide vine-ripened, mature fruit directly to the customer, who can consume this within a day or so of harvest.
Smaller growers who can obtain a premium price from direct sales are also more willing to deal with the production difficulties of heirloom cultivars if it means they have a specialized niche market for their produce - they don't have to compete with large producers or imported supplies of fruit. The popularity of heirloom tomatoes will continue to increase as consumers become more aware of them through dining and gardening magazines, TV coverage, and as they see these tomatoes show up in dishes at their favorite up-market restaurants and on the shelves at local markets.
What Is a Heirloom Variety?
Heirloom tomato varieties are generally regarded as those which have been grown for many decades and have a long history of small-scale, backyard production. To met the criteria of being considered a heirloom, a tomato variety must have grown for over 50 years, be open pollinated, must grow true-to-type from seed collected from the fruit and must have its own history or folklore. Many consider the term heirloom to refer to varieties which have been grown, selected, preserved and handed down through generations of family members. There are also many varieties considered to be heirlooms which are popular old commercial releases that have been in production for decades and pre-date the development of modern tomato hybrids. There are many hundreds of tomato varieties considered heirlooms. Both determinate and indeterminate varieties exist as heirlooms, and the quality and yield potential is highly variable.
Advantages and disadvantages of Heirlooms
Hydroponic producers should be fully aware of the advantages and disadvantages of heirloom tomato production and trials would be recommended before undertaking large scale production. These open pollinated cultivars require a greater degree of skill than modern hybrids as they mostly lack the generative traits, disease resistance, and shelf life quality characteristics which have been bred into standard greenhouse cultivars. Most heirloom varieties also have little resistance to a number of potentially serious diseases. Plant breeding with tomato hybrids over the years has seen vast improvements in disease resistance to most of the serious pathogens such as fusarium, verticillium, mosaic viruses and a range of others which has greatly improved the reliability and consistency of greenhouse production. Heirlooms however often subcomb to disease under a range of environmental conditions, particularly when heat and humidity are high. For this reason, heirlooms often need a protective spray program to combat common tomato diseases which most modern hybrids are resistant to. Hydroponic growers however have an advantage over field production of heirlooms, as environmentally controlled greenhouse which prevent the foliage from becoming wet, use of heating, clean water and sterile growing media all assist with prevention of disease outbreaks.
Another major drawback with most heirloom varieties is the presence of physiological disorders which downgrade the fruit quality and appearance. Many are prone to radial cracking, crazing or splitting due to the thin skin and lack of tolerance to many environmental conditions. Some consistently produce misshapen fruit caused by cat facing, while others are prone to fruitlet drop or blossom end rot. Many small scale producers accept that a high 'pack-out' rate will occur with many heirloom varieties and channel second-grade fruit into value added, processed products such as sauces and preserves.
Yield variability is perhaps the greatest disadvantage with heirloom tomatoes and growers can manage this problem by carefully assessing a wide range of heirloom cultivars to determine which has the yield and fruit characteristics most profitable. Various studies have been published which evaluate a number of heirloom tomato cultivars for yields and fruit quality and these provide valuable data when selecting cultivars to trial.
The advantages of heirlooms are that despite the production problems and lower yield potential, they do have a well established and rapidly growing niche market that will benefit smaller growers willing to put the time and effort into the production. Also, there exists huge potential within the genetic pool of heirloom tomato varieties to find the types that will produce well and receive premium prices. The range of colors, sizes, shapes, growth forms, and flavors gives a wide selection for growers to experiment with and produce a product which is unique on the local market. Many commercial hydroponic tomato producers may also chose to grow a smaller area of heirlooms as an additional market line to their standard greenhouse varieties. Hydroponic organic production of heirlooms offers yet another high value niche market that skilled growers may take advantage off.
Hydroponic production
The hydroponic production of heirloom tomato types differs somewhat from the standard greenhouse hybrids. Because these older varieties are more prone to serious disease pathogens which can severely limit production, preventative measures should be taken where ever possible. One of these is the use of rootstocks which can prevent an outbreak from the array of diseases that older varieties may develop. Grafting the heirloom variety onto a disease resistant root stock gives the plant the ability to resist certain root diseases, but also improve yield potential as most root stocks provide the plant with a healthier and more vigorous root system. This system of grafting allows the production of heirloom fruit, while utilizing modern plant breeding for disease resistance via the root stock. One study found that grafting heirloom tomatoes onto the resistant tomato rootstocks GRA 66 and Hawaii 7996, did not wilt under high soil disease pressure from bacterial wilt and produced significantly higher harvestable yields (Rivard and Louws 2006). The rootstock Maxifort has also found to enhance plant vigor and yields when used with heirloom varieties. Where bacterial wilt might be a problem, heirloom types can be grafted onto suitable, resistant eggplant root stocks. Other root stock varieties with resistance to fusarium wilt, bacterial wilt, verticillium and TMV - as well as the ability to increase plant vigor - are a good way of increasing disease resistance in heirloom varieties which would otherwise be highly susceptible.
Growing media and nutrition
The same sterile growing media currently used for greenhouse hybrid cultivars can be used for heirloom varieties. Growers may chose substrates more in line with organic production for these older varieties such as coconut fiber or various mixtures of composts, coir, pumice and natural materials. However hydroponic heirlooms are also successfully grown on rockwool slabs, in NFT and on other substrates. Due to their susceptibility to various root disease such as bacterial wilt and fusarium, growing media should be sterile and greenhouse floors kept clean and free of debris and soil contamination which could carry disease spores into the crop. Substrate moisture levels need careful control and monitoring with heirloom types as over saturation can predispose the plants to wilt pathogen outbreaks and irregular watering will cause fruit splitting and cracking in a much higher rate then with modern hybrid types. Substrate moisture meters are a useful tool with heirloom production to keep root zone moisture consistent throughout the day and night.
Heirloom varieties also need careful control of plant nutrition. Modern greenhouse hybrids have been bred to withstand the use of high EC levels and conductivity is often run at increasingly higher rates in these crops to maintain fruit quality. Commercial growers may run EC as high as 4.0 5.5 to restrict vegetative growth and promote a generative plant form with high fruit solids, however most heirlooms would suffer production problems at the high EC levels under which many hybrid crops are grown. High EC applied to heirlooms often promotes blossom end rot (BER), small fruit size and loss in yield, although compositional quality and dry matter percentage in the fruit is often very high under these conditions. Lower, constant EC levels should be used on heirloom plants under most circumstances and only slight osmotic pressure applied to improve fruit quality in those varieties which are not prone to splitting or blossom end rot. It is likely that due to the lower yields of most heirloom types that their requirement for potassium are not as great as a very high yielding hybrid crop which has been bred for vigor and rapid ion uptake. This coupled with the fact that many heirlooms are prone to BER under high EC and potassium can restrict the uptake of calcium - which is essential for BER prevention - means that nutrient formulations for heirlooms are likely to be slightly different than those used for hybrids. Heirlooms may also benefit more from foliar sprays of trace elements if vigorous rootstocks are not used, particularly during times of heavy fruit set or during the establishment phase.
Heirloom varieties can be trained in much the same way as hybrids - to an overhead wire, and layered where necessary. Due to the lower vigor of many heirloom types they may grown different densities to hybrids, although this is highly dependant on the particularly heirloom variety being produced. Many growers may chose to offset the lower rates of vigor by taking an extra shoot or head during good growing conditions to increase yields per plant with some of the heirloom types. Pollination with the older varieties is much the same as with hybrid production, however under cooler growing conditions, the frequency of manual pollination should be increased to ensure that sufficient pollen is transferred for fruit set. Many of the heirloom types are prone to pollination problems under less than idea conditions and this results in a large proportion of the early crop developing catface and other deformities. Keeping greenhouse temperatures well within range during the early crop development phase assists with optimizing fruit shape and yields on the first few trusses. There are also heirloom types which perform better as early-season crops which will set good sized and evenly shaped fruit under cooler conditions, and mid-season croppers which are more suited to production during warmer seasons or in fully heated greenhouses.
Determine vs indeterminate
Among heirloom types are both determinate or bush type and indeterminate tomatoes and while both can be grown hydroponically, most commercial growers select indeterminate varieties and grow these in much the same way as greenhouse hybrids. This allows more flexibility of production as indeterminate vines can be cropped for a longer period of time before replacement and the upward training allows good air flow around the base of the plants to assist with disease prevention. Under certain circumstances, such as high disease pressure, heirloom varieties may be grown as a short term crop, removed after the production of 1 3 trusses and replanted. This system has advantages in overly warm and humid climates where diseases limit longer term production. Determinate or bush varieties can be grown in greenhouses where suitable varieties can be found. Although they are self supporting, most benefit from staking to keep fruit from resting on the floor and to assist with air movement round the base of the plant.
Specific problems with heirlooms disease and physiological problems
Apart from various root pathogens such as bacterial wilt and fusarium which can be controlled with use of resistant rootstocks, most heirlooms are also susceptible to a number of foliar and fruit diseases. Late blight development can be rapid late in the season and result in premature termination of crops, although some heirlooms such as Cherokee Purple, Eva and Purple Ball have been reported to have some natural tolerance to this disease. Septoria and other foliar diseases can also be a severe problem, although keeping the foliage dry and prevention condensation assist with control of these pathogens. Some heirloom varieties are claimed to have some overall or improved `disease resistance' however individual growers will need to assess these traits for themselves under their particular growing conditions
Heirlooms are also susceptible to Botrytis which can cause widespread crop losses when humidity levels are high and air movement inadequate. Under conditions which promote the development of fungal and bacterial diseases, heirloom crops should undergo a protectant spray programme to prevent fungal spores from developing. Any infected plants should be removed from the cropping area to delay the spray of disease throughout the crop.
Pests in heirloom varieties can be controlled in much the same way as with all other tomato crops and regular plant monitoring for insects should be carried out.
Physiological disorders
The main cause of downgrading of heirloom tomato fruit are physical defects and physiological disorders. Many of the larger fruited heirlooms naturally produce a large blossom end scar and radial cracking. Others typically have concentric and calyx cracking on a larger proportion of the fruit. While consumers may be more accepting of these defects on heirloom fruit, large cracks and splits can result in fruit decay shorting after harvest. In media systems, careful control of irrigation to prevent large fluctuations in moisture content will assist with prevention of splitting. Other physiological disorders such as zippering, cat face, russet, blossom end rot and misshapen fruit can be reduced using similar methods as in hybrid crops
Heirloom cultivar selection and some common heirlooms
Selection of the most suitable heirloom varieties for commercial hydroponic production can be daunting because there are literally hundreds of types on the market as the interest in growing these varieties increases. Different countries and regions have their own history of tomato heirlooms and there are many seed companies who offer a huge selection of well-known and virtually unknown varieties. Commercial growers must also take into account not only which varieties may have the highest degree of 'old- fashioned intense tomato flavor' the reason these fruit are often purchased but which are going to be the most productive and attractive to customers.
Among heirloom varieties there is a wide range of not only fruit sizes, but fruit types which are used for different applications. Many of the roma and similar meaty types were originally grown for sauce and processing. Some are more suited to drying and preserving while others have excellent qualities as 'slicers' for eating fresh. Cocktail, cherry, medium-sized and large beefsteak varieties exist amongst the heirlooms, as do the elongated, flattened and pointed fruit types. Some growers select from each of these categories and market the fruit in mixed trays or baskets to customers who may want to sample a range of heirloom types.
Of the wide range of heirloom tomato varieties for which seed can be obtained, there are a smaller number of well known older types which many customers may be familiar with and these would be the recommended varieties for hydroponic growers to start with. Of these, Brandywine (red, pink and yellow), Moskvich, Green Zebra, Black Prince, Trigrella, Black Krim, Mortgage Lifter, Kelloggs Breakfast, Pineapple, Aunt Rubys German green, Cherokee Purple, Rutgers, and Oregon Spring would be some of the more commonly grown heirlooms, although there exists potential in many others for hydroponic greenhouse production.
Yields from various heirloom varieties have been reported from field trials carried out in the U.S. While a wide selection of cultivars was assessed in many of these trials, not all heirlooms have information available on potential yields, fruit numbers or average fruit size. In a study carried out in 2004-2006, it was reported that the highest yielding heirloom was Mortgage Lifter, followed by Giant Belgium and Pineapple (Maynard 2007). Another study found the varieties Lemon Boy and Black Prince to be the highest yielding (Vavrina et al, 2003). An earlier study reported the varieties 'Ten Fingers of Naples', Beefsteak extra large, Costoluto Genovese and Platillo to be the highest yielding. In contrast, Yellow Pear, Old German and Hillbilly were determined to be the lowest yielding. (Cimmarrusti and Shoemaker 2002).
Descriptions and history of some common heirlooms
Black Krim
Originally from the Black sea area of Russia and claimed to have been smuggled into the U.S. before the breakup of the Soviet Union. A medium-sized fruit with a deep dark red color that cracks easily. Indeterminate with an early growth habit. Flavor is described as sweet.
Brandywine
Brandywine pink is an Amish heirloom dating back to 1855 and is the most well known of all heirloom varieties. Fruit is pink with green shoulders, large in size (350 700 g each), prone to cracking and producing misshapen fruit. Flavor can be strong when grown well. Although the true Brandywine is pink colored, other varieties such as red, black and yellow brandywine are now on heirloom lists, although their origin is confusing.
Mortgage Lifter
Developed in the 1930's by 'Radiator Charlie' Byles of West Virginia. Charlie sold plants of this variety for $1 each and paid off his mortgage in six years. A well-known heirloom made popular by the story of its development. Indeterminate plants, very large red fruit (up to 1 Kg in weight) with a mild, sweet flavor and tough skin. Claimed to have some disease resistance and to be highly productive.
Aunt Ruby's German Green
Large fruited green beefsteak. Indeterminate and of German origin.
Amish Paste
An Amish heirloom known at least since 1885. Indeterminate and produces heart- shaped large fruit (up to 225 g) with thick flesh and few seeds. Considered to be a sauce or paste variety with a high brix.
Black from Tula
Russian heirloom. Indeterminate and produces medium-sized fruit with a flattened shape and deep brown red color. Locular gel is dark green when ripe and often has green shoulders. Flavor is considered rich and complex.
Cherokee purple
A variety which can be traced back more than 100 years to a Cherokee Indian tribe. Also listed as a Tennessee heirloom. Fruit are dark reddish purple in color, medium in size and crack easily due to a thin skin.
Evergreen
Large fruited green beefsteak. Indeterminate, sweet and highly-flavored when ripe.
Garden Peach
French heirloom variety. Indeterminate. Fruit is bright yellow with a red blush when ripe and a slight peach-like fuzz on its skin. Fruit is small-to-medium in size. Produced in large clusters with a mild flavor.
Green Sausage
Elongated green fruit with yellow stripes. Determinate bushy plants. High flavor profile and brix levels.
Costaluto Genovese
An Italian heirloom variety which produces large, semi-ruffled meaty red fruit. Vigorous indeterminate variety. High yielding and productive.
Harbinger
A traditional English variety introduced in 1910 and popular with English gardeners.
Rutgers
A standard heirloom variety with globe-shaped fruit, crack resistant and medium- sized.
Kellogg's Breakfast
Large orange-colored beefsteak which originated in West Virginia preserved by Darrell Kellogg.
Prince Borghese
An Italian heirloom variety with small red fruit 2 to 5 cm long, plum-shaped and originally used for drying in Italy. Determinate.
Yellow Pear
Dates back to the late 1800's. Determinate plant with small golden yellow pear- shaped fruit. High flavor and brix levels.
Moskvich
Early indeterminate type originating in Russia. Fruit are dark red and globe-shaped with a moderate flavor.
This is just a small selection of heirlooms. Growers should consult seed suppliers for the characteristics of other varieties and trial a wide range of types before starting commercial production.
Heirlooms for flavor
Tomato fruit color has little effect on flavor profile, despite the fact that consumers often perceive a bright red fruit as being sweeter than a lesser colored sample. There are varieties of heirloom tomato which are green at maturity and these have some of the highest brix and flavor scores of all the older types, however consumer perception may need to be changed to accept some of these types when they are accustomed to only seeing red fruit in the supermarket chains.
The flavor potential of many heirlooms has been assessed in a number of studies in recent years, often in an attempt to uncover which of these older types posses genetic flavor factors which could be used in breeding programs with modern hybrids. The results of a number of studies demonstrate that under the right growing conditions, some of the heirlooms do have high brix and acidity levels which would give a flavor advantage. However not all heirlooms are highly flavored and growers do need to evaluate fruit flavor in variety trials rather than assume all heirlooms will be highly flavored and outperform hybrids on taste tests.
One U.S. study ranked the following heirloom cultivars as having a brix level of 6.0 or more: Currant Tuscan Bombolino, Ernies plump, Goliath, Howard German, Jersey Devil, Joe's Plum, Large Polish Paste, Opalka, Oscar, Persimmon, Riesentraube, Sausage, Super Italian Plum, Tyboroski and Yellow Pear. While the cultivars Rutgers, Abraham Lincoln, Costoluto Genovese, Homestead, Long Keeper, Martino's Roma, New Jersey, and Oregon Spring came in lowest ranking in terms of brix levels in the same study (Cimmarrusti and Shoemaker 2002)
Seed collection and saving
One advantage of heirloom variety production is that seed can be collected and saved from ripe fruit produced on-site since these open pollinated types will grow `true to type'. The plants that you collect seed from should be selected based on health, vigor and yields. Fruit should be fully ripe when seeds are extracted. Pulp and seeds are scraped from the inside of the ripe fruit, mixed or washed with water to remove the fruit tissue and the resulting seeds dried for several days before storage.
Harvest and marketing of heirlooms
Heirloom fruit are often sold as `vine ripened' which gives them the highest possible flavor quality, but severely reduces their ability to withstand grading, packing and transport. Heirlooms sold in this way will need additional packaging compared to thick-skinned hybrids which are bred to handle transportation. Heirlooms should be individual hand-harvested by cutting the peduncle rather than pulling from the vine. Many heirloom types can be difficult to harvest as the fruit has not been bred to form a well developed abscission layer that allows the fruit to be quickly snap-harvested from the plant. Keeping the calyx on heirloom fruit assist with promotion of shelf life and prevents the thin skin from tearing as the calyx is removed roughly during harvest. Because the presence of the calyx on the fruit can puncture the flesh of adjacent fruit, these need to be kept in a single layer in harvesting and transport boxes or trays. If the calyx is to be removed, this should be done carefully after harvest so as not to tear the flesh.
Vine ripening does it affect flavor?
Heirlooms can be harvested mature green - as with hybrid fruit - and ripened fully under room temperature conditions. However since most heirloom crops are sold direct, they are best marketed when at least partially colored, particularly those with interesting coloration such as the black, pink, yellow and multi-colored types. Just as with hybrid varieties, there is much debate about whether vine-ripened fruit have a higher compositional quality and flavor and those harvested mature green or with the first signs of coloration. There is also confusion about what `vine ripened' means - consumers often assume the fruit has been plucked from the vine when fully colored to table maturity. However some producers consider `vine-ripened' fruit to be that which is harvested at the `breaker stage' when showing the first visible signs of color. Studies have shown that total sugars in tomatoes increased progressively during ripening from the mature green to fully red stages and that those harvested in the earlier stages of ripeness were rated by taste panelists as less sweet, more sour and less `tomato-like' then those harvested at a table ripe stage. Also, it has been reported that the quantity of volatile compounds which contribute significantly to the flavor of fresh tomatoes is always lower in fruits ripened after harvest than those fruits fully ripened on the plant. With this sort of compelling evidence, growers of heirloom tomatoes looking to maximize fruit flavor should be harvesting as close to the `table-ripe' stage as possible.
Sources of heirloom tomato plants and seed
Johnny's Selected seeds- www.johnnyseeds.com
W. Atlee Burpee & Co- www.burpee.com
Seed Savers Exchange- www.seedsavers.org
References
Rivard C L and Louws F J. Grafting provides sustainable and profitable technology in organic heirloom tomato production. Department of Plant Pathology, Raleigh, NC 27695.
Adel A, Kader M, Stevens A, Albright-Holton M, Morris L and Algazi M., 1977. Effect of fruit ripeness when picked on flavor and composition of fresh market tomatoes. Journal of the American Society for Horticultural Science Vol 102(6) 724 731.
Granges A, Gillioz J M, Quentin H and Ahmed O, 2006. Old tomato varieties: agronomic, analytical and taste values. Revue Suisse de Viticulture, Arboriculture et Horticulture Vol 38 no 2, 97 - 103.
Vavrina C S, Armbrester K and Pena M, 2003. Growing Heirloom tomato varieties in Southwest Florida. Fact Sheet HS921, Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Cimmarrusti D and Shoemaker W H, 2002. Heirloom tomato cultivars evaluation at Saint Charles, Illinois 2002. Saint Charles Horticultural Research Centre.
Maynard A A, 2007. Heirloom tomato trials 2004 -2006. Bulletin no 1008 The Connecticut Agricultural Experiment Station, New Haven, USA.
Stern D J R, Buttery R, Teranishi R, Ling L, Scott K and Cantwell M., 1994. Effect of storage and ripening on fresh tomato fruit quality. Part I. Food Chemistry Vol. 49 225 231.
Rodriguez-Burruezo A, Prohens J, Rosello S and Nuez F., 2005. 'Heirloom' varieties as sources of variation for the improvement of fruit quality in greenhouse-grown tomatoes. Journal of Horticultural Science & Biotechnology Vol. 80(4) 453 460.
