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Growing Tomatoes Successfully Despite Cold Temperatures and Rain

June 16, 2010

I’m still grumbling about the cold, wet late spring we’re having in Seattle. I like some sunshine, and I like some heat. And so does my garden.

Under 50F in June Does Not a Good Tomato Make

Under 45F Does Not a Good Tomato Make

Sure, rain out of the sky is better than rain out of the tap. It’s likely more pure, and it’s certainly less expensive. With all the rain we’ve had so far this spring, I haven’t turned on my irrigation once. That’s a bonus. But in return, I’m having to tent crops like garlic to protect it from too much rain and keep it from rotting. As well, I’ve had to come up with creative solutions to get my heat-loving crops into the ground and growing despite the cold.

My first line of defense against unpredictable Seattle spring and summer weather is to grow tomatoes designed for short, cool growing seasons. And, I grow them from seed (or at the very least buy starts from local growers who produce starts designed for this area). A few of my favorite tomatoes for our region are Oregon Springs, Stupice, Siberia and Gold Nugget. Plus, this year I’m trying out another – Peron. These have proven to hold up against the cold, grow strongly and withstand fungal diseases like blight.

My next trick is to do several successions of seedings and potting. This way, if an early crop fails, I have others coming up behind them. Even in a short growing season, this can make a difference.

Container Grown Oregon Springs Tomato

Container Grown Oregon Springs Tomato

When we face a spring like this one, where mid-June temperatures struggle to reach even 50F, my next trick it so mix up my growing techniques:

Greenhouse Pots: I pot up several tomatoes into 3-10 gallon, black plastic containers. I recycle plastic grower containers that previously contained large shrubs and trees. The black absorbs heat and keeps the roots warmer and happier. These containerized tomatoes will never go into the ground; I will keep them in the unheated greenhouse indefinitely. If it heats up enough, I can move the pots out into the garden later in summer. If the summer continues to have flip-flop weather, I may be moving the pots in and out of the greenhouse on warm days. This helps ensure pollinators visit them as they troll through the garden for food. If it doesn’t heat up at all, I keep them inside and lure in the bees to do a bit of pollination work on these potted plants.

Determinate tomatoes and cherry tomatoes are ideal for this method. It also works nicely for late season crops.

If you don’t have a greenhouse, rigging up a temporary hoop house can work nearly as well.

In Ground Protection: At a certain point, the plants simply must go into the ground. I plant them into the ground on one of the warmer days when soil temps are more friendly.  And, since tomatoes will root off their stems, I pinch out several leaf nodes to bury more stem and encourage more strong rooting. Then, I rig up protective sheeting. In some cases, another hoop house may be in order. But, if your hoops tend to be short and your plants will grow tall, this may not be a long term solution.

A Dozen Plastic Sheeted Tomatoes in the Hellstrip

A Dozen Plastic Sheeted Tomatoes in the Hellstrip

This year, I modified my hoop house concept in the hellstrip, attaching ventilated plastic sheeting to the square tomato cages. The ends of each row are open to allow some air ventilation, which helps keep down disease. As well, pollinators can enter through these openings. The plants are mostly protected from splashing and benefit from the added trapped heat inside the plastic. However, the surrounding soil gathers rainwater, upon which the plants can draw. It may not be pretty, but remember that word – tolerance. Everyone has their level!

Any kind of tomato developed for cool season production can do well in hooped areas. Just be sure to always check for disease. Make sure they have plenty of water. And try not to let the plastic contact the growing leaves; this can burn them or trap water, which becomes conducive to disease growth.

If your tomatoes are in the ground (or even in a pot) and look awful, consider them carefully.

  • If they have fuzzy fungus growing on the stems, yank them and dispose of them. You may already have late blight. There’s no coming back from this, and if you don’t get rid of an infected plant you will likely infect the rest of your plants and any number of other plants throughout your community.
  • If they’re turning colors that aren’t green, you may need to provide fertilizer. Rain can cause nutrients to rush out of the soil rapidly. (Note: discoloration can be caused by a number of other factors as well.)
  • If they just haven’t grown at all you may have a stunted plant. Sometimes digging up and replanting is the answer. Sometimes yanking a failure and starting over with a strong new start will give you better results.

Have questions about your tomato situation? Let us know.

Have a fantastic variety you love to grow, please share!

Already have fruit forming despite a cold, wet season?  Share your secrets, please!


  1. Elaine says:

    I just noticed that my Sungold cherry tomatoes have started to set! I’m growing them in containers alongside the south-side of my house.

  2. This is of course the year that I chose to grow 72 tomato plants in a new area of my garden. I did them in raised rows with the ground covered with plastic. There are just too many for me to do hoop houses as per my usual. I’m just praying that they will survive this spring along with doing daily sun-dances! Kim

  3. I started mine under plastic but I removed it in mid May when I planted out the peppers and basil and they needed protection. Mine are thriving with no cover because of some other measures I’ve taken.

    1. Raised beds with gravel surrounding – provides good drainage and retained heat (think hot rock massage)
    2. Red plastic mulch covering the ground
    3. Metal roofing material 24″ tall inside the raised beds keeps the rats out but also has the added benefit of absorbing heat and reflecting the sun’s rays, the red from the ground cover and the heat from the north and east sides of the tomatoes. It’s worked so well, in fact, that I already have tomatoes turning red on my 4th of July but also have tomotoes on stupice, sweet 100, brandwine, san marzano, cherokee purple and jaune flamme that I started from seed in mid February indoors.

    I couldn’t be happier about the tomatoes this year – they are going crazier than the potatoes despite this crummy weather!

  4. Shauna says:

    I am also in Seattle and have been trying to grow Juanne Flam and Purple cherokee tomatoes. The plants look big and healthy, but have failed to produce fruit yet…..My Juanne Flam has flowered, yet no tomatoes have formed. The purple cherokee has yet to flower. Any advice would be greatly appreciated!

  5. rhaglund says:

    Have the flowers simply closed and fallen off or are they blooming and just need a pollinator? Also, what are you doing for fertilization? Too much nitrogen can cause the plants to put on a lot of green growth but can also keep them from producing as many flowers &/or fruit. You may need to adjust to maximize your production.

    Try putting the blooming plants near plants that attract bees. Thyme, borage, lavender and many annuals bloom at the same time as tomatoes and can help lure in the pollinators to do the work. Bumblebees do most of the tomato pollinating, so definitely attract those.

    Another trick is to put them somewhere you get a good breeze (not wind). Tomatoes can set fruit when breezes blow the pollen around. Some cultivars are harder to get fruit set on than others. Purple cherokees tend to set fairly well. I’m not familiar with the Juanne Flam.

    Good luck!

  6. Shauna, those are later varieties and we’ve had a BAD tomato year so don’t be disheartened. I started mine from seed end of January and I don’t have any of those varieties ripe yet, and all the tomatoes on them are tiny. I even have other measures that caused our tomatoes to ripen early this year, we have been eating the 4th of July tomatoes since end of June.

    Last year even though we had an unusually warm and early year for tomatoes my purple Cherokees were the last to ripen. Just keep them in fish fertilizer and it will happen.

  7. doreet says:

    thanks, all; I have just returned to Eugene, Oregon, (I am a native, worked in California for many years) and I am very frustrated trying to grow anything here, again,to the point of depression.

    We did not have any summer, at all, last year, it was the coldest on record; everything rotted,molded, cause there was no sun,no heat,in July.All summer it was cold, rain,no sun,no heat, we had ALASKA FOR SUMMER. iT Gets worse every year here, everyone will have to grow anything INSIDE greenhouses, or the house. Farmers all having bad year, like last year,it will destroy all farming here. World Climate Change has hit; it also hit California, the same, my sister told me, from there. Tomatoes ? I cannot grow anything here, much less tomatoes.

  8. Judy says:

    I’m also trying to grow tomatoes in this wet, cold summer we’re having in the Seattle area. I made a big mistake and built a small hoop house using clear plastic from Home Depot. The plastic continually has condensation–big drops of water all over that drip down on my tomatoes. As cold as it is today, I’m going to remove the plastic because tomatoes are not supposed to be wet all the time. I have opened the ends and provided some ventilation, but this does not work. There is still condensation. I also have a couple of determinate tomatoes growing in large pots. I put plastic over their tomato cages also, and the condensation is really extreme with these plants.

    Any advice? Can I used some sort of row cover instead of plastic?

  9. Judy,

    Thanks for writing in. A few thoughts:

  10. Change out the clear plastic for something semi-opaque, which will filter the sunlight more than just intensify it, which can fry your plants.
  11. Try taking a hole punch to the plastic and add in some ventilation that way.
  12. Not only ventilate from the ends of the hoop house, but also open the base of the hoop house a few inches, which will help pull air through the space
  13. Reduce watering significantly. If you’re getting that much condensation, it may be that you’re adding too much water into the system itself.
  14. Certainly, you can switch to using row cover instead of plastic. This won’t keep as much moisture off the plants & it won’t increase heat as much, but it can help just a little bit.
  15. Good luck!

  • Paulo says:

    No, I still can’t do tomatoes here in Iceland. They grow very slowly and set flower but no fruit yet,

    What are the summer temperatures of you guys?

    Mines are lows 45ºF, Highs 56ºF, often rain. And I am trying with siberian tomatoes.

  • Paulo, Although we have relatively cool (for the US) summers, we do get long days that can get very warm during the day (even breaking 100F at times). Your best bet is probably going to be varieties like ‘Siberia’, which can apparently set fruit even in cold temperatures. Growing determinants, which don’t put excessive energy into green growth, may be a good way to go too. They get to one size, set fruit and that’s about it. They’re good for short season locations. Good luck & let us know how well your tomatoes turn out!

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