I paid a visit to the Union Square Greenmarket in New York City in April and vendors were selling huge, garden-ready tomatoes, big pepper plants, and tons of basil. The entire scene gave me an intense case of envy, because the we have to wait until late May to plant tomatoes in Seattle and it’s best not to even think about basil until mid-June.

In the Maritime Pacific Northwest (and in places that have short summer seasons or cool nights), growing tomatoes, peppers, eggplants, and melons is a huge challenge. Tomatoes grow best when temperatures stay above 60 degrees F and below about 85 degrees F. But in Seattle, our average nighttime temperatures never get above 57 degrees and our average daytime highs, even in the height of summer, barely nudge past 75.

Over the last few years I’ve discovered a few strategies to help out my tomatoes, and I thought I’d share them with you. Even if you’re lucky and live in the Midwest or Mid-Atlantic states (aka Tomato Heaven), these tips can help you get started earlier and grow bigger, better, healthier plants:

1. Choose the right variety. I avoid varieties that take longer than 85 days to mature and mainly grow ones that were bred to thrive in cooler climates or shorter seasons. I like ‘Oregon Spring’ and ‘Legend’, which were both bred at Oregon State University to set fruit at cool temperatures. I also like a few heirlooms that were bred in Siberia (I figure if they grow in Siberia, they’ll grow in my garden!), including ‘Odessa’ and ‘Moskovitch’. I also always plant ‘Green Zebra’ and  several cherry tomatoes, especially ‘Black Cherry’, ‘Matt’s Wild Cherry’, and ‘Yellow Pear’. If you like big, beefsteak tomatoes try ‘Chianti Rose’, I’ve had great luck with it! 

2. Heat up the soil. Tomatoes and other warm season crops like to sink their roots into soil that is at least 60 degrees F (but 65 or 70 is even better). Rather than wait for my soil to heat up, I use plastic to help things along. Start by weeding your bed and raking it smooth. Then water it until the soil is soaked down to at least 8 inches. Stretch clear plastic across the soil as tightly as you can and weigh down the edges with soil or rocks. The plastic acts like a greenhouse and heats up the soil. I usually leave it on for two or three weeks before planting.

Trench Tomato Planting Technique

2. Plant in a trench. It pays to bury as much of a tomato stem as possible because the little hairs on the stem develop into roots when they come into contact with soil. When I’m ready to plant my tomatoes, I pull the plastic  off the soil (you can leave it on all summer, but I don’t like the way it looks). I then plant my tomatoes in a shallow trench that is about four inches deep and as long as my tomato plant is tall. Before planting, pinch off any flowers and the bottom leaves on your tomato plant. Then, lay it sideways in the trench and bury the root ball and bottom portion of the stem in soil. Gently bend the top of the tomato up so the leaves are above the soil line. Don’t worry, the plant looks crooked at first, but it straightens up as it grows. I space my plants about 3 feet apart to ensure plenty of air circulation.

3. Mulch. A lot. After planting, I water the plant in really well and then pour 1 cup each of diluted fish emulsion fertilizer and liquid seaweed onto the root zone. Then I apply about ½ inch of compost around the base of the plants and a 3 inch deep layer of grass clippings or straw on top of that. The compost slowly releases nutrients every time you water and the mulch insulates the soil, which helps it stay warm. This mulch system also prevents moisture from evaporating out of the soil quickly and keeps down weeds, which means I have to spend less time watering and weeding. After mulching I install super sturdy tomato cages made from wire mesh around each plant. 

Cozy, Warm Tomatoes

4. Keep the plants warm. This year I’ve placed Wall-O-Waters around each of my tomatoes. The Wall-O-Waters look like water filled teepees and they act like mini solar greenhouses. The water absorbs energy from the sun during the day and then releases heat at night, which helps keep the tomatoes warm and growing fast. 

5. Water at the base. The best way to prevent fungal diseases like late and early blight is to keep your tomato foliage dry. I do this by watering my plants at their base. This year I’m investing in soaker hoses, but in the past I’ve always hand watered. The trick to hand watering is to get a water wand with a long neck and a toggle that turns off the stream of water at the handle. That way you can bring the hose over to the garden and nestle the wand in at the base of the plant. Then, simply turn the water on to a slow stream and water the plant deeply. Before moving on to the next plant, turn off the stream of water. This saves water and prevents you from unnecessarily spraying your tomatoes and other plants with water. I try to soak the soil about 6 to 8 inches deep every time I water, and I wait until the soil dries down to my second knuckle before I water again.

My Favorite Organic Fertilizers

6. Fertilize, but not too much. I’m still working on building really healthy soil in my P-Patch and the new soil in our raised beds needs more organic matter. This means I have to fertilize a bit during the growing season. Typically, I spray my plants once a month with a half and half mixture of diluted liquid fish emulsion and liquid seaweed. I spray the entire plant, including the undersides of the leaves, until it is dripping. 

This system has helped me grow great tomatoes, but I’m super curious to find out what tricks you guys use on your tomatoes.