Growing Tomatoes in Idaho

Growing tomatoes in the Pacific Northwest isn't hard but it's not as easy as pie.

The key to successful tomato growing here is to grow a fast growing, early maturing variety. Do not bother buying seed for beef steak tomatoes; they will not ripen before the weather turns cool and rainy in the fall. Instead, either buy starts from local nurseries that always carry varieties suited to your climate or buy your seed from a local seed catalog like Territorial Seed Company. I've also found that Johnny's Selected Seeds offers varieties that are suited to the Northwest climate.

I start my tomato plants from seed on the first of March and grow them under lights in my basement. I start seed in 4" pots and thin to 2 plants per pot in the first week or so.

They're usually ready to be transplanted into gallon cans around April 15th. I plant three plants in my greenhouse--two in the ground and one in a very large pot--proof that tomatoes make a great patio plant too. I plant these on April 15th so they don't every see the gallons.

I plant my outdoor tomatoes two ways. One batch gets planted under a large plastic cloche about May 1st. This cloche can be closed up entirely to keep the plants warm on cold days and nights but can also have it's sides rolled up to keep them from getting too hot on those rare sunny days in May. There are always a couple to tantalize you into thinking summer has come early when it's not so. The plants usually are busting out the top and sides about June 15th and I take the cloche off entirely. Since the cloche is only in use for about 6 weeks I can usually get the plastic to last 4 or 5 seasons before I have to replace it.

The other batch gets planted singly here and there in the garden. I either surround their cages with plastic to keep them warm or if I'm feeling particularly lazy I just wait to plant them on June 1st. By then the weather has warmed enough that the plant's leaves won't turn purple due to the cold. And they seem to do just as well this way. If the plants have gotten pretty big I bury a portion of the stem in the ground when I plant them to give the plant a bigger root system over time.

Favorite Varieties
I've tried all sorts of varieties over my time of growing tomatoes in the NW and my favorites are First Lady, Santiam, Sweet Million (a wonderful cherry tomato), Brandywine (an heirloom variety that has superior flavor) and for the greenhouse I grow Territorial's Greenhouse 761 Hybrid. Every year there are new varieties to try and new types introduced. Find what you like and go for it. Experiment if you have the space. It's not hard to find people who will accept your excess crop.

Seed vs. Starts
I just like to grow things from seed. It's a bit like magic that a huge plant could grow from that tiny seed. But not everyone has the space, time or patience for it. If you're going to buy starts it's much better to buy small plants with good roots than to buy a gallon can with a plant with a few fruit already set. I know that the gallon is really tempting because it has that fruit on it but studies show that plants like that tend to bear less fruit than ones with no fruit. If you insist on buying a large plant at least find one that hasn't set fruit yet. I try to get my plants in the ground before they start blooming and they do pretty well that way.

Cages vs. pruning
People can spend hours arguing the merits of one kind of pruning and trellising versus another. I haven't seen any real difference in the success of my plants using one method versus another--blasphemy! So I made my wood tomato cages and put them over my plants at planting time and let them grow. It's quick. It's easy and I get more tomatoes than I know what to do with. What more could you want?

Mulches etc
Studies have shown that tomatoes do better with red mulch. But until they make a red biodegradable mulch I'm sticking to compost! Feel free to experiment, that's what gardening is all about.

Fertilizer
Tomatoes are heavy feeders. They like fertilizer. I use my universal mix in the bed when I plant outdoors and that's it. In the greenhouse I give them another shot of organic fertilizer mid-summer because of the higher temperatures and the longer season. The plants in the greenhouse get lots bigger than the ones outdoors.

Watering
Tomatoes like to be evenly watered. Don't let them dry out too much and don't overwater them, especially once they have fruit on them. The fruit will split and get moldy which is very sad. I use drip irrigation and water once a week outdoors and for 20 minutes every other day in the greenhouse. If we get an inch of rain in a week I don't water outdoors.

Crop Rotation
As with most crops, it's a good idea to plant your tomatoes in a new location each year. I try to rotate mine so that they don't return to the same location for at least 3 years. I also make sure that it's been at least a couple years since potatoes, who are close cousins, have been grown in the same location.

Pests and Diseases
The biggest problem with tomatoes in the NW is Late Blight. It's the disease that caused the great potato famine in Ireland. It's a soil born fungus-like pathogen. It likes mild temperatures (60 to 80 degrees) and wet conditions so it can be a big problem in a cool wet summer. The pathogens in the soil splash up onto the plants and they rapidly reproduce in cool wet conditions. One week your plants will look fine, the next they'll look at little droopy and the next they will have turned black and slimy. There is no saving the fruit, they rot too--trust me, I've tried salvaging fruit that looked fine when I picked it and in a few days they were mush.

If you have an attack of late blight do not plant either tomatoes or potatoes in that bed the next year. Don't put the dead plants in your compost pile--it takes high temperatures to kill the pathogen and most of us don't don't get our compost hot enough to kill late blight. Put it the trash pr your yard waste barrel.


Happy Tomato Growing This Year