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.

Preventing tomato blossom end rot

If you are lucky you may have never seen this gross looking anomaly on the bottom but if you are like the rest of us you probably have seen this disorder especially on your first fruits of the season. Fortunately with some precautionary measures you should be able to minimize the effect of this on your harvest.

There are three primary causes for tomato blossom end rot; inconsistent watering, calcium deficiency, or abundance of nitrogen in your soil.

Calcium Deficiency: In most cases calcium deficiency is not the culprit but with minimal effort you can be proactive to eliminate it as a possibility. If you remembered to through in some egg shells and some Epsom salt when you planted your tomatoes you should be good, if you are like me and was too excited and forgot it is time to supplement. There are a few remedies out there including powdered milk, egg shells, Tums, or even some bone meal tea. I personally go the egg shell tea method, which simply requires taking some egg shells soaking them in water overnight and applying to my tomato plants. If you do this method you will want to prevent spread of salmonella make sure you bake them in the oven for 10 minutes at 200 degrees. One bonus is this also makes the egg shells break up much easier. The best time to apply this egg shell tea is when you baby tomatoes are just starting to form since this is the time your little fruits are sucking up as much calcium as it can find

Inconsistent watering: I have an entire post on watering your garden but the basic idea is to not to drown your roots but watering too often, but not wait until they become completely dry either. Without water your plants have no means to get needed nutrients including the calcium mentioned above. For me this is the most common cause of of my blossom end rot usually after going on a week vacation with no plan for watering my garden while I was gone.

Too much nitrogen: From my experience if I have too much nitrogen I normally get tall plants with no blossoms until the nutrients in the soil balance out. Where you can get into trouble is side dressing (supplemental fertilizing during the growing season) your plants if you do this make sure you provide a balanced fertilizer such as compost tea or commercial brand that is specifically for tomato plant and follow the directions on the box. Plants much like ourselves can only absorb so much nutrients from the soil so we need to make sure we are providing what the plants need at that time in their growth cycle and remember when it comes to fertilizer more is not better in most all cases it will be worse.

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