By Conner Voss
The month of May has ushered in my appetite for summer fruits, and tomatoes of all types are no exception to this sun-induced hankering. Late spring is stuffed full of delicious anticipation: we dream of tomato-basil salads, and our soils are warmed and ready to receive summer seedlings. In as little as a month, vigorously growing transplants will begin to show flowers, and mere weeks later, we’ll be devouring our first handful of fresh cherry tomatoes. If this sounds like fantastical hogwash, read on for five tips to transform your tomato-growing tribulation into triumph.
1. Don’t put all of your tomatoes into one crate.
Choosing an array of tomato varieties will help to broaden the harvest season while also diminishing the risk of crop failure due to pest, disease, and/or deficiency. For example, determinate tomatoes–compact plants that grow to a genetically determined size, and then ripen most of their fruit within a short window of time - typically yield earlier in the season and do not require extensive pruning or trellising. Their counterparts, the indeterminate types, will continue extensive growth and fruit development as long as conditions are favorable and pests and disease are kept at bay. In general, certain varieties of tomatoes are more prone to cracked fruit, fungal disease, and blossom end rot (the un-appetizing expression of a calcium deficiency, and very prominent in sauce-type roma tomatoes). In the demonstration garden, we usually plant two or three varieties of each determinate and indeterminate. For determinate varieties, Glacier and Scotia are highly dependable, disease resistant, early producers of tasty red slicers. For indeterminate varieties, we enjoy Black Cherry, Stupice, and Cherokee Purple, among many others. There’s just never enough space to trial every tantalizing specimen.
2. Give ‘em root room.
Wide spacing is the easiest way to encourage full growth potential and abundant harvest with minimal inputs. In my experience, the roots of one mature tomato plant will penetrate a circle six feet in diameter, and up to four feet deep. When a plant’s roots are overly crowded, competition for water and nutrients is the inevitable outcome, and without extra attention, growth rates will falter, along with the harvest. Our low-maintenance, minimal-input standard is to plant tomatoes 24-30 inches apart in beds well-amended with compost and/or organic matter from past season’s legume cover crop.
3. Start Strong, Start Early, and Coddle Considerably.
Not all starts are created equally. When examining a seedling for planting, we are looking for strong, stout stems, dark green leafy growth, and well-developed (but not bound) root systems that balance the “above-ground” foliage. Because tomatoes are quick growing, heavy nitrogen feeders, they respond noticeably to fertilizers and foliar feeding, especially during early vegetative growth (before fruit set). Unfortunately, it is a common practice to pump-up retail seedlings for a leafy aesthetic that does not necessarily equate to survival in the harsh realities of the spring garden. An unbalanced root/shoot relationship at transplant can lead to slow growth and impaired immunity as seedlings adjust to their new home.
In my opinion, minimizing shock is the definition of success for tomato culture. The same might be said for peppers and eggplant. The most commonly made mistake, of which I am very, very guilty, is to rush into Spring with my proverbial planting pants down. The short frost-free window of our northwest season can be frustratingly unwelcome to heat-loving crops, and so it is no wonder we are chomping at the bit. How many times have we pulled our two ripe Brandywines from the vine just as the rains begin in September? To this, I say season extension. Warming the soil before planting, keeping seedlings in a healthy and vigorous holding pattern, and employing heat-capturing cloches are all helpful methods for reducing shock. Here’s a quick run-down of this year’s tomato planting schedule in the demonstration garden:
03/04 – Seeded tomatoes to plug trays under lights, with heat mats.
03/15– Covered future tomato beds with a plastic cloche to dry and warm the soil.
3/24 – Transplanted tomato seedlings into 2” pots, and watered with a weak dilution of kelp and fish emulsion. Put on heat mats in the greenhouse.
4/10 – Monitored soil temperature under covered beds. Approaching 60 degrees during the day. Removed trays from heat mats. Light foliar feeding.
4/20 – Continued to monitor soil temps, and transplanted some tomatoes up to 4” pots. Light foliar feeding.
4/25 – Prepped bed for transplant. Added a layer of compost and complete organic fertilizer.
5/1 – Began to move seedlings outside, to “harden-off” in a protected area.
5/10 – Transplanted tomatoes under hoop cloche. Covered with floating row cover and plastic. Evening temps read 60+ degrees.
4. Snip, Tuck, Tie.
Managing the growth of our tomatoes through pruning and trellising is helpful for a number of reasons. In my experience, pruned tomato plants develop fewer, larger, higher quality fruit that ripen earlier. Also, plants pruned to a limited number of “main stems,” are much easier to trellis and therefore, access, during harvest. Lastly, pruned and trellised plants allow for better airflow and sun exposure, minimizing the incidence of fungal outbreaks.
In short, pruning tomatoes is all about channeling energy through the plant to capitalize on the production of fruit. The first rule of thumb is that we don’t prune determinate tomatoes. The growth pattern of determinates is compact and easily handled with a cage, or sometimes nothing at all. Also, remember that there is a finite amount of fruiting potential with determinate varieties, and that the fruit ripens in one flush rather than all summer – therefore, pruning is counterproductive. With indeterminate varieties (except cherries, which we let go crazy), we prune to maximize the health and strength of one to three central leaders, and to ensure that the fruit on those stems is receiving the sugar it needs to fully ripen and mature. Pruning 101 is better demonstrated in the garden than put into words, and a simple search on the Internet will offer a flood of resources, videos, and experts on the topic. My quick explanation is as follows:
Tomatoes follow a predictable growth pattern, whereby auxiliary shoots (also called side branches or suckers) emerge from each leaf notch (the point at which the leaf connects to the main shoot, also called a node). As a tomato plant grows, the shoot apex (the top) produces leaves and flower clusters in sequence, with the most mature leaves and fruit being lower down on the plant. Generally, this sequence involves two or three leaves and then a flower cluster, two more leaves, etc., if we were to follow the stem from soil to shoot apex. If we remove suckers, this is a relatively easy pattern to identify. Left unchecked however, each sucker that forms at the leaf nodes along the main stem will follow the same growth pattern as the apical shoot, developing it’s own set of leaves, flowers, and suckers. With no pruning, the typical indeterminate tomato variety becomes a tangled mass of stems and leaves and immature fruit that is very difficult to trellis. Usually this results in damp foliage and fruit laying on the ground, and a frustrating harvest.
Side branches and suckers are easily removed when young simply by pinching off with a fingernail, or gently snapping to one side. If, like me, you forget to prune for a couple of weeks, larger suckers should be removed with a sharp knife, taking care not to leave a ragged stump. If multiple “leaders” or main shoots are desired for your system, leave the first one or two vigorous side shoots that develop early in the season, but continue to prune all subsequent suckers, on all leaders. My preferred method is to prune to one or two leaders, because I find that such a plant is easily kept upright with simple and cheap trellis materials.
- Perhaps the easiest form of trellising - especially if you don’t plant a lot of tomatoes in rows - is to utilize one eight feet long stake (cedar or redwood), or piece of bamboo, or metal t-post, per seedling. With loosely tied loops, so as not to cut into the growing stem (thick twine or strips of old bed sheets work well), the central leader is easily trained to grow up the sturdy pole. By also securing the plant near the base of fruit clusters, we further bolster against the downward force of a heavy yield. It is a good idea to make sure your posts are plenty sturdy, and that you sink them into the ground within a week of transplanting so as not to disturb the developing root system. The basic premise is a sturdy and gentle support for the growing leaders, which can get upwards of seven feet tall. All sorts of materials, from fencing, to recycled lumber, to teepees and tree prunings can be fashioned into sturdy trellises.
5. Plant deeply and water the same, drip by drip.
Tomatoes are an incredible species in that they will sprout roots from just about anywhere. In an overly humid greenhouse I’ve witnessed cherry tomatoes turn leaves into alien-looking aerial roots. During transplanting this is a good quality, as it allows us to increase the rooting potential of our seedlings. Inevitably, due to low-light and stressful conditions, some of our tomato starts become spindly, long, and weak stemmed. To remedy this, we’ll pinch off the lower few leaves of the plant, and bury a good portion of the bare stem. Within days, new roots will begin to sprout, increasing the seedling’s ability to uptake water and nutrients, as well as providing a strong, sturdy support for the main stem.
Another physiological feat is the tomato’s ability to thrive with very little supplemental irrigation. As mentioned earlier, tomatoes are incredible soil prospectors, with massive, efficient root systems. It’s not so much that a tomato plant doesn’t need ample amounts of water; it’s that, given the space to fully develop, roots will find water already existing in the subsoil. Profound root growth requires two important management tasks. The first is to provide ample space between individual plants. In a completely dry-farmed situation, I would recommend 36-48 inches The second root booster is to water slowly, deeply, and infrequently (maybe once a week or less) during plant establishment. The aim is to recharge the soil profile to a depth of three feet or more, which will encourage the plants to seek water on their own, and to become more resilient water users. Shallow roots are more susceptible to damaging fluctuations in temperature and moisture, and less able to withstand drought in the long run. Deep and infrequent is the irrigation mantra. Another notable benefit to deeply-rooted plants is access to mobile minerals, like calcium, which settle in the fine particles of the sub-soil. With ample moisture and calcium, our Roma tomatoes are much less likely to suffer unsightly blossom end rot. Lastly, consistent cultivation of the soil surface creates a thin layer called “dust mulch” which impedes water evaporation from the valuable soil-well, while also keeping weeds under control.
These are my five, constantly morphing, golden rules of tomato culture, and though arguably nonsensical, are certainly justified in the sweet, juicy, conclusion. For a full disclaimer, I should mention that my favorite tomato is relatively small, thick-skinned, fleshy, and pucker-sweet in that eye-popping, hold me back, I can’t stop eating these, my mouth is raw kind of way. That’s the tomato I’m aiming to build. What kind of tomato do you grow? Drop me a line, and let me know, or find us in the demonstration garden at Luscher Farm.
Conner Voss has left the Organic Education Center to devote himself full-time to farming. We honor his passionate love of the soil.