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The Truth About Heirloom Tomatoes!

XKCD: Duty Calls

I hear a lot of people say well intentioned but not always accurate things about tomatoes, and it’s time to set the record straight.

Disease Resistance

It’s true some (not all) modern tomato varieties have some special disease resistance. The most important diseases are Fusarium and Verticillium wilts. These are different but similar diseases, with nearly identical symptoms, and depending on your climate you may have one or the other in your soil but probably not both. If your plants get this the leaves will become seriously wilted, and while they may still produce some tomatoes the harvest will be much lower than usual. This is soil borne, so you may have it in one part of your garden but not another. It’s not very contagious so if a plant gets it you may as well let it grow and see what happens.

While these wilt diseases are common, most gardeners probably won’t have them in their gardens in which case they are simply not an issue. It’s not worth losing sleep over this until you know for sure you have this problem! If a wilt disease is present in your soil, there is little else you can do except grow resistant tomato varieties or grow your plants in pots with known disease free soil like purchased potting soil, home made compost or a mix of the two.

It’s worth mentioning some heirloom varieties may have some resistance to these wilt diseases, no one really knows because there hasn’t been much research done on this.

For the home gardener, modern tomatoes don’t have any other important disease resistance!

The other disease resistance in modern tomatoes is only important to farmers. For example the tobacco mosaic virus generally only occurs in greenhouses, but because it is common in tobacco plants if you do smoke you should be sure to keep your tobacco away from your tomato plants and wash your hands before gardening.

Heirloom tomatoes have disease resistance too! For most other plant diseases, some resistance can be found in a few heirloom tomato varieties. For example common tomato and potato diseases are early and late blight, and while no tomato has complete resistance to these, some currant tomatoes have shown a little resistance. No commercial varieties have any resistance to these two blights.

It all depends on what diseases you have in your garden, and it’s important to understand this before coming to the conclusion that choosing either commercial or heirloom varieties is the answer.

It’s Not Necessarily True Hybrids Are More Productive

There is often the assertion, usually by seed companies trying to sell more seeds, that hybrid varieties are more productive. This is a very disputed assertion! The basic idea is that if you have a highly inbreed plant variety, it can show signs of inbreeding depression which can result in lower yields. Since creating a hybrid variety is essentially the opposite of inbreeding, it must result in higher yields.

The flaw in this logic is that tomatoes are naturally inbreeding plants, and don’t usually have problems with inbreeding depression.

It’s not that productivity gains are not possible in hybrids, but it’s not always true and many heirloom varieties can be as productive as hybrids.

It’s Not Always True Heirloom Tomatoes Taste Better Than Hybrids

Commercial varieties are almost always breed for supermarket cosmetics, growing and transportation convenience and low cost of production. Taste is not usually a factor when they are developed.

If you compare a heirloom tomato to a commercial variety under these circumstances, it’s certain to taste better.

You can make your own hybrids! By choosing two of your favorite heirloom tomatoes and cross-pollinating them, you can easily end up with a tomato that tastes better than any pure breed OP or heirloom variety.

The parent varieties of commercial varieties are generally kept secret, so it’s not possible to experiment with or improve on these. If you make your own hybrids you can collaborate with other gardeners and work together on finding great combinations.

There Are Problems With Heirloom Varieties

All food plant varieties need to be periodically ‘grown out’. This means a large number of plants, sometimes numbering in the hundreds, are grown out and selected for desirable traits. Plants with undesirable traits are rogued out or removed, and seeds are saved from plants with desirable traits. When this isn’t done, the genetics of a particular variety will deteriorate slowly over time and develop undesirable traits leading to problems like susceptibility to diseases or pests, loss of productivity and loss of quality.

Growing out plant varieties takes time and money. Some home or hobby gardeners do large scale grow outs, but this involves only a small percentage of heirloom varieties. Commercial varieties simply have the money and support of large companies behind them who can afford to grow them out more often and maintain them better.

Many heirloom varieties are in a very bad state in this way! This is not just tomatoes but all different kinds of fruits and vegetables.

Also, because many heirloom varieties were developed in a single person’s garden or in a single region they have become ‘landraces’, that is well suited for that particular region. If you try to grow a variety like this in a different region, it likely won’t perform as well.

There is Something You Can Do About This

It may not be possible for you to grow hundreds of plants in your garden and do a full scale grow out of a particular variety, but you can do this yourself on a smaller scale.

If for example you are able to grow in the neighborhood of 10-50 plants of the same tomato variety, only save seeds from the best ones and hopefully do this for a few years in a row, you will likely end up with a significantly improved variety which has also been acclimated specifically to your garden.

Other Things You Can Do To Improve Your Chances

Talk to other gardeners and find out what’s done well for them. In particular if a nearby gardener has found something that does well in your climate, consider getting some seeds from them and growing it too.

Not all seeds are equal. If something didn’t do well for you, but did well for someone else who got the seeds from somewhere else, consider getting some of the same seeds and trying again. I know the Seed Savers Exchange is doing grow outs of many of their varieties, and I imagine other seed companies are by now too. Consider that improved seeds may soon become available for popular varieties.

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Record Weather

A number of records have been broken recently concerning extremes in weather. January this year (2008) was the second warmest on record, since they began keeping records in 1706. The warmest January on record was last year (2007).

Last year I started all my plants indoors at the usual time, and planted them out also on schedule. Had I know the weather was going to be so warm, I could have put them out two months earlier. This year I’m going to assume the weather is going to be warmer and not wait before putting some of my plants out.

Yesterday another record was broken. This record was for the highest barometric pressure ever recorded in February. This has meant for the last several days the weather has been sunny and very dry. Anyone who lives in a northern maritime climate will know this is not normal for February. This meant it was a good day for taking pictures.

Amsterdam Prinsengracht

This is the Prinsengracht canal near my house.

Garden Path

This is the view from my garden along the path leading up to it.

Common Kale

There’s not much growing in any of the gardens right now, with the exception of kale. Lots of the gardens have a few of these plants. I don’t know the name of the variety, but it’s what everyone calls ordinary kale. I never saw it before I moved to the Netherlands, but it’s everywhere here, and it tastes nice. I think it’s an F1 variety. This gardener’s plants aren’t doing well and are a little small. He also has red colored as well as green, which I’ve never seen before.

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Seed Trays

Seed Tray

For those of you new to starting seeds indoors, or those who have never used a seed tray, I would really suggest giving one a try. Almost every seed I start indoors begins in a seed tray.

The main reason is when starting seeds you almost always sow a number of seeds, which don’t all germinate, then you choose one or more from what’s left. A seed tray works a lot better, because instead of putting a few seeds in a number of different pots, you start with all the seeds in one place.

For example, if you want three of the same tomato plants, you might plant 10 seeds in a tray. Out of these 10 seeds, a few probably won’t germinate and one or two others won’t be healthy for some obvious reason. You can then choose the five best seedlings, and transplant them into their own containers. Out of these five seedlings, you can plant the best three and give the others away or discard them. In this way, you end up with the three best plants available from the 10 seeds you started with.

If you have six or eight different kinds of plants you want to grow at the same time, you can just make little rows in the same tray, and use plastic markers so you know what is what (like in the picture). Since trays take up a lot less space than pots, you will need fewer lights and less room to start so many different plants.

Another possibility is you have some old seeds, and you don’t know if they will germinate anymore. For example, I grow celeriac (celery root) each year, and the seeds come in packets containing hundreds of tiny seeds. If you take suspect seed like this and simply broadcast it over an entire seed tray, as thickly as you think is appropriate, and even just a small percentage of it germinates, you can just transplant out the seedlings that do emerge. Even if you get a much higher rate of germination than you expect, it’s not difficult to deal with a lot of seedlings in a tray as long as you don’t wait too long and let them become too established.

Some plants, most notably tomatoes, become stronger if they are transplanted. Tomatoes have naturally weak root systems, and also have the ability to form roots on any part of the plant that becomes buried. What I do is transplant them from the seed tray, as deeply as possible into a plastic pot. Only the top few leaves should remain above the soil. Then when I transplant again out into the garden, I again bury the plant all the way up to the top few leaves. In this way, the plant is ‘shocked’ into developing stronger roots.

Mostly I have very close to a 100% transplant success rate with seedlings from trays, only a few kinds of plants will not tolerate being transplanted out of a tray into a pot.

While you can use a number of things as a homemade tray, I suggest buying a proper tray from a garden center. It will have the proper drainage holes on the bottom, and be the proper depth for working. Trays come in many different sizes and they all work equally well. My trays are about 15x20cm. If you use a heating pad when starting seeds indoors, think about buying trays that will fit nicely on it.

A heating pad can be very useful. Some plants, like peppers will not germinate unless you keep them above 22C/70F day and night, and since many people’s homes are not that warm at night a heating pad is the perfect solution. Keep in mind a heating pad will cause your plants to dry out more quickly, so be sure to water it often. Once your seeds have germinated, the heating pad is no longer useful and should be turned off.

It can help seeds germinate if you cover the tray with a piece of kitchen plastic with a few holes poked in it with a fork for air. This helps keep the moisture in. Be sure to remove this plastic after 24-48 hours or mold can form. I use a purchased ‘propagator’, which is a heated tray with a plastic lid that works in a similar way.

Normally you want to transplant the seedlings out of the tray as soon as the first set of ‘real’ leaves form, this is the set of leaves that come after the initial cotelydons. To transplant, just loosen the planting medium with a table knife or something similar and pluck the seedlings out gently with your fingers. This will be easier if the seed tray is not too crowded. Except for tomatoes which can be planted much deeper, most seedlings should be transplanted to about the same depth they were in the tray. If you have trouble at this stage with the seedlings breaking or being too delicate, it’s sign they didn’t get enough light.

Before starting any indoor planting project, especially if you are reusing containers from the previous year, higiene is very important to avoid plant diseases. I suggest first cleaning everything with a little soap and water, then sterilizing it by soaking for a few minutes in water with a little bleach added.

You can make your own seed starting mix from homemade compost, but it has to be sterilized by cooking it in a warm oven for about 30 minutes. Otherwise, commercial seed starting mix can be purchased. When making your own seed starting mixes, be sure everything is sterilized first, and remember seedlings are very delicate and even the most gentle or natural of fertilizers can be too strong and kill them. It’s commonly suggested that you let the seed starting mix sit around for a month or two after adding your own fertilizer to it in order to let it ‘cool off’.

One of the best overall planting guides I’ve seen, as well as charts for determining when to start different plants indoors, can be found here.

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The Moat

The Moat

Here’s what my garden looks like from a distance. Canals on three sides keep it dry. Around the corner to the right is also a canal. The canals also function as a security barrier, keeping out unwanted visitors.

The water level is only 30-45cm (1-1.5 feet) below the surface of the garden, keeping the ground at least a little wet almost all the time.

Sometimes the ground is too wet. Over the weekend I was digging in the greenhouse. Even though the weather was clear and warm (just like this picture), when I came back on Monday I found it raining inside the greenhouse because the water was evaporating from the freshly dug earth and condensing on the inside of the glass. I think it may be a challenge to keep the inside of the greenhouse dry enough throughout the summer.

In case you are all wondering why I posted pictures of the rain water collection containers a few days ago, when I have all of this lovely water right next to the garden, let me assure you it is not suitable for use in the garden. There is too much dumping, legal and otherwise, and the water is very dirty. We had to dredge some of the canals a few weeks ago, and what came out smelled like a mixture of motor oil and sewage. There is enough flow through the canals that the water is exchanged about once a day with fresh water that comes from the ground together with rain water, and this flow is enough to keep our gardens clean.

In theory at least I could dig a hole, a pond if you like, that I could use to grow water plants or as a source of water for the garden. I think with this I might have the problem of mosquitoes or other insects. I don’t know of anyone else in the garden complex who has tried this. Perhaps with a little work I could create a balanced ecosystem with fish and so on. Anyway, this is a project for another year, first a garden!