A day-long workshop on tomatoes at the Maine Organic Farmers and Gardeners Association last spring brought up some tips that should help plantings produce more and longer, and with less disease. These tips came from MOFGA and Cooperative Extension staff and a few growers.

• Plant tomatoes in a well-drained, non-compacted soil with a pH between 5.5 and 6.8 – ideally closer to 6.8, for better taste. Try to have 4 to 6 percent organic matter in your soil, and be sure potassium, magnesium and calcium are balanced according to soil test recommendations to avoid some physiological disorders of tomatoes. Stressed plants are more prone to some diseases than plants that have optimum soil and climatic conditions for growth.

• Planting into a warm soil (60 F at 3 inches deep) can reduce the time to maturity by a couple of weeks, over planting in cooler soils. Black plastic can hasten soil warming in the spring. If you use organic mulch, don’t apply it until after soils have warmed.

• Orient plants so that prevailing winds move down the rows, keeping foliage dry to minimize disease problems.

• Apply about a cup of liquid fertilizer, such as fish emulsion, to each plant as you transplant.

• Prune plants to one or two main stems to produce earlier, larger, more uniform fruit and to increase air flow around plants.

• Remove leaves and side shoots below the lowest flower cluster (except the shoot that will become the second main stem, if you’re growing plants with two main stems). This helps reduce disease by removing potentially diseased leaves and by increasing air flow in the planting.

• Prune plants early in the morning when plants are turgid, snapping them off with your fingers, with clippers or with an Exacto knife.

• The easiest way to contain tomatoes in the field is to use a basket weave system. For short (determinate) varieties, put a 4-foot stake about 1 foot in the ground between each two or three plants. For determinate (vining) varieties, put a 5-foot stake about 1 foot in the ground between each two or three plants. Weave twine in and out of the stakes, all the way down the tomato row, and tie it to the end stake. Then come back on the other side of the row, weaving the twine in and out on that side. Weave the twine about 1, 2 and 3 feet above the ground (and 4 feet, if needed) as tomatoes reach those heights. Remove the tops of plants when they’re as tall as the stakes. Mark Hutton, Maine’s Extension vegetable specialist, demonstrates basket weaving at https://www.youtube.com/watch?v=XSf3aSj46jo.

• Try to maintain even soil moisture to avoid problems such as growth cracks in fruits.

• To harvest, twist fruits gently off plants.

• To minimize the chance of late blight, grow potatoes from tubers that don’t harbor the disease (e.g., certified disease-free tubers); and remove any volunteer potato plants that come up from last year’s tubers that you missed during harvest. If you see late blight early in the season, remove dying plants and cover them with a tarp so that spores don’t spread, or bring them to the dump. If you see late blight later in the season, spread cull potatoes and other infected plant material in a single layer on the field so that they freeze, killing late blight. Don’t put them in a pile (even a compost pile) and don’t leave them in the ground, because they may not freeze in those places.

• Rotate tomatoes, potatoes, eggplant and peppers (all in the Solanaceae family) to new ground each year or two (or even three, for some diseases), and clean up all debris at the end of the season. Some diseases, such as Septoria leaf spot and early blight, overwinter on plant debris, tomato cages, plastic mulch, stakes, seeds, etc. Clean stakes with a product such as Oxidate.

• Remove lower leaves from tomato plants up to the first cluster of fruit to remove some disease inoculum, to increase air flow around the plants, and to expose developing fruits to the warmth of the sun, which helps them ripen faster. As the first cluster of fruit ripens, remove leaves up to the next cluster.

• Watch for hornworms (or for their frass — excrement — which is easier to see than the caterpillar itself) and pick them off or use Bt (Bacillus thuringiensis) to control them. Hornworms began appearing in the Midcoast area around the first week of August this year.

• Remove all but four or so flowers or small fruits per cluster so that remaining fruits don’t pull the cluster down. Sometimes the first flower on a cluster makes a misshapen fruit, especially in heirloom tomatoes, so that can be a good one to remove.