10 Tips for growing tomatoes in the Northwest


Unfortunately we do not have no where near the preferred climate to grow tomatoes.  We have extremely mild temperatures with summer maximum average high of 78°F and maximum average lows of 59°F.  Take that with our very short window of consistent rain (bringing blight) tomato plants are lucky to even be surviving when planted in our area let alone have a tremendous yield, though with a little planning and care you can be eating delicious tomatoes from your garden.

1. Pick the right variety.  You want to choose a plant that has has a low number of days to maturity.  Given we have a very short growing season this can significantly improve your chances of growing some ripe red tomatoes.  Some good examples of tomato varieties to try followed by the average days to maturity Early Girl (52), Goliath (60), Juliet (60), Oregon Spring (58), Sugary (62), or Sunsugar (62).  You may also want to consider growing smaller tomato varieties such as cherry or globe which can be beneficial given the smaller the fruit the shorter amount of time is takes to ripen which could allow you to harvest your tomatoes before the rains along with the diseases.

2. Start with big plants.  Paying a couple dollars more on your tomato plants can shave off a 2-3 weeks off your “days to maturity” number so go for the largest plant you can afford.  On a budget (or just cheap like myself) plant your seeds early and make use of a greenhouse or grow box to make your own more mature tomato plants and save yourself a considerable amount of money.  If you do purchase a larger plant, don’t be in a hurry to get it into the ground…let they nursery keep it alive for you until you have optimum environment to plant it in your garden.

3. Plant at the right time.  Even more important that the air temperature is the temperature of the soil you can actually plant tomatoes with a soil temperature of 50°F but the closer you can get to 60°F the better your plants will respond.  When it comes to measuring your soil temperature you can use a standard inexpensive soil thermometer but personally I just use my handy digital grill thermometer and if you are concerned about using the same probe in your meat than your dirt you can always pickup a extra temperature probe.


4. Work in the trenches.  The temperature of the soil can vary by 5-10°F as you dig deeper into the soil.  By planting your tomato plants in a trench no only do you get the benefits of a larger root but also a root system much closer to the surface of the soil which can provide several additional degrees to your advantage.  One disadvantage to this method is you do need to be diligent with your watering due since the ground will obviously dry out on the area closest to the surface.


The process for planting trenched tomato plants is very simple. Dig a shallow trench about an inch lower than the root ball. Lay the plant on its side removing an stems that are about to be buried. Cover with soil and pack down lightly and use some sticks to help support the plants until they get adapted to their new orientation.  Unless it is pouring down rain when you plant them like I did be sure to water your plants well after planting.

Note: I intentionally took the photo of these plants a few hours after planting to show the expected shock they should encounter…this is normal don’t be alarmed they will perk up in a day or two.

5. Keep your plants warm.  As mentioned before the temperatures are almost ever warm enough but fortunately there are a few products to help out a little for this:

These Red Tomato Teepees are simply filled with water and absorb heat during the day and then slowly release it during the night and is advertised to help bring you yields up to 6 week earlier than without them.  This provides more adequate temperatures for your plants and also some insurance for cold spring mornings.  These are fairly inexpensive and can easily be collapsed and stored away when not needed.
If you have a small number of plants to provide a little shelter you may want to consider a cold frame.  These provide a few extra degrees of protecting during the cold nights but also protect the plants from high winds and hard rains.  You can also use this as a little hot box for your peppers once your tomatoes are more established.
image If you really want to go all out you can also consider soil warming cable this is simply a cable you bury into the ground and plug it in and will provide heat underground where the roots need it most.  Now I will be the first to admit this may be more of an extreme measure for your tomato plants but if you are considering growing crops all year round this could be a good investment.

6. Grow your tomatoes in upside down planters. 
One of the advantages of growing tomatoes upside down is the planter is exposed to the heat from the sun thus increasing the soils temperature providing better temperatures for the roots of your tomato plants to grow.  Now whether you opt to make your own upside down planter or use one of the commercial versions such as the TopsyTurvy, this can be a great way to sneak your plants out at least a couple of weeks earlier.


7. Don’t let your tomato plants get wet.  Living in the Northwest, rain happens and there is not much we can do about it.  This moisture can spread disease and promote fungal growth so the less moisture you can get on your plants leaves the better.  There are a few things you can do to reduce the amount of moisture on your plants.  First, when watering your plants avoid getting water on the leaves.  Simply water the soil right at the surface, this can be easily done with a soaker hose, long wand spray nozzle, or even a simple watering can.  If you are experiencing some hard rains at the end of your season you may be able to delay blight by installing a slight overhang over your tomato plants.  By taking some rigid clear plastic and installing over your plants you can reduce the amount of rain that falls directly on your plants while not inhibiting light getting to your plants.

8. Fertilize.  Providing the right nutrients to the plants as they need them can help encourage their growth and provide vigorous plants in the shorter period of time.  The problem with tomatoes is if you over fertilize your plants will simply grow larger and fail to produce fruit as can be seen from this tomato plant I had growing out of my compost bin.


I provide a weak balanced fertilizer such as alfalfa pellet applied every couple weeks to the top of the soil allowing them to break down and provide nutrients on each watering.


Once the plant begins to set flowers I switch to applying about a 1/4 cup of bone meal to each of the plants about every 3 weeks to allow the plants to get the phosphorous they need during for reproductive function at this this time.

9. Many plants with less tomatoes.  The less tomatoes your plants has ripening on its vines the more energy it has to get them to that nice delicious red color for picking.  By pinching off all the suckers not on the main vine you will get your tomatoes to ripen more quickly while taking less space.  By doing this I can plant my tomatoes 18-24” apart allowing me to get a few extra plants in to make up for some of this lost yield ending up with less green tomatoes at the end of the season.

10. Get supermarket quality tomatoes from your garden. Of course tomatoes ripened on the vine will have the better taste but when your season runs out and your tomatoes are still green what can you do?  One option is to take any flawless tomatoes (no bruises, no cracks) place them very gently in a cardboard box padded on bottom with newspaper and place in a cool humid location. You may also add a ripe banana to speed up the process by adding a little extra ethylene.  If you are luck in a couple/few weeks you should have some red tomatoes.

2 Responses to “10 Tips for growing tomatoes in the Northwest”

  1. Rob Says:

    Or leave them in the green house for a undetermined amount of time.
    Seriously I find, like you said, a lot of it has to do with the right variety of tomato. Some i found that do well for me are Robin’s Egg and tumbler (Cherry) and Window Box Roma. This year I am trying a bi-color tomato called Virgina Sweet.

  2. Jennifer Says:

    Great tips! Some other short-season tomatoes include: Bingo, Carmelo, and Valerie. All have some degree of disease resistance. Then there’s Stupice and all the Russian heirlooms. I learned about these when writing my book “Edible Gardening for California”, which some of your readers might find helpful. For tomato diseases (I already have Early Blight!), I’m trying a new organic spray called Serenade. Good luck with your crop!

    Tweeting as JEBWrites

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