TOMATOES

Who doesn’t love homegrown tomatoes? I think most of us do, and I’d say they are my favorite thing to grow. Every time I buy a tomato from the grocery store I tell myself it wasn’t worth the bother or the money and tell myself never do that again. But, there always comes a time I don’t have a garden, there’s red tomatoes at the store, and I cave in and buy them anyway. Even if they are organic and have a nice color, they’ll usually end up having no flavor. The first tomato I picked from the garden here, after my hiatus during our move, reminded me once again of the magnificent flavor of homegrown! It certainly is worth it to grow your own.

GROWING TOMATOES AT HIGH ELEVATION

Upon moving here, I knew from the start that growing tomatoes at this elevation would be a challenge and I may not be successful. I’d heard that it is possible to grow tomatoes here with special care and extra warmth at night, so I was ready with whatever I could do short of building a greenhouse (at that time).

My plan that first year here was to grow tomatoes in a bed that would be covered every night with plastic. On the coldest nights, frost cloth would also be laid over the tomatoes as a blanket for added warmth. Dark colored plastic bottles filled with water and placed around the tomatoes could soak up warmth from the sun during the day, to be released at night inside the plastic dome.

I grew just one bed of tomatoes: Glacier (55 Days), Coldset (65 Days), Siletz (65 Days): All these are determinate tomatoes, chosen based on cold-hardiness and early maturity.

They had 6 weeks of growth prior to transplanting outdoors. In my experience, giving tomatoes more indoor growth did not produce a better plant, nor produce an earlier harvest, so I stuck with 6 weeks. Tomatoes were planted outdoors on June 15th.

The first tomato I was able to harvest was the Glacier, 79 days after transplant. Several more tomatoes of all varieties were harvested between this date and September 23, when all remaining tomatoes were harvested prior to a freeze. Many of these tomatoes were green to yellowish-green, and I was able to ripen them indoors. At that time, our greenhouse had just been built, so they were placed on racks in the greenhouse until ripe. They were a bit mealy and didn’t have as much flavor as the vine-ripened tomatoes, but I had done all I could.

CONCLUSION: Although I did get some tomatoes from the outdoor garden, I decided that due to the inconsistent summer weather, the need to constantly watch and cover the tomatoes nightly, and the high probability of frost/cold in early September, I’d only grow tomatoes in the greenhouse in the future, even in the summer months. Typically we only get a couple nights all summer that are 50° or more. Due to the small size of the greenhouse I won’t be planting large numbers of tomatoes for canning projects as I did in our previous garden, but will only keep a few for eating fresh.

HIGH ELEVATION GROWING TIP: TOMATOES

Tomatoes really grow best greenhouse here, but if you don’t have one and and you live lower than 9,000′, give a couple of tomatoes a try outdoors. Choose a cold-hardy variety with the shortest # of maturity days.

Start your tomato plants indoors, about 6 weeks prior to your average last frost date. Transplant them out after the last day you think it will be freezing, and keep them covered every night throughout the summer if your temps are under 50°F.

If your tomatoes don’t ripen prior to freezing temperatures in the fall, just ripen them indoors. If possible, only pick tomatoes for indoor ripening if they have a little yellow or orange tinge started. This shows they’ve begun the ripening process, and will ripen better indoors. Unfortunately, the indoor-ripened tomatoes will be a bit mealy and have little flavor. They’re not so good for fresh eating, but roasting them will bring out the flavor for soups or marinara sauces. The very green ones won’t really ripen, so use these for fried green tomatoes or green tomato relish.

MOUNTAIN GREENHOUSE TOMATOES

With our greenhouse heated year-round to no less than 55ºF, tomatoes are now grown exclusively in the greenhouse. We almost always have about five tomato plants either growing or bearing fruit. They’re grown in succession, so every couple of months it seems I’m starting a couple more. It is possible for the tomatoes to continue to grow and produce for a year or more, but I usually remove them before that to keep rotating the plants in each section of soil. I anticipate when various plants (cabbage, lettuce, etc.) will be harvested, and start growing a new tomato for the spot 4-6 weeks before the other plants will be harvested. I find that tomatoes started between October and January don’t do so well, but starting them between February and late September should produce a decent plant that produces nice tomatoes.

Since I use the greenhouse year-round, I do the best I can to rotate plants and keep the soil replenished between plantings. Please see more about this in “Growing Food in the Greenhouse.” For the summer months I have discovered that the tomatoes grow better in the back half of the greenhouse near the deck overhang, where they get less direct sun and stay a bit cooler. In the winter I grow them in the front row, near the warm windows.

There is one corner by a wall and a central post in the greenhouse where I typically grow 1-2 indeterminate tomatoes. I train them up the wall or post and across, hanging from the beams. The remainder of the tomatoes are determinate, shorter plants. I occasionally put one or two cherry tomatoes in a hanging basket.

SELECTION: For the greenhouse I’m not so concerned about “days to maturity” since I knew there is warmth in the greenhouse indefinitely. However, I find that during the fall, winter & early spring months it takes a LONG time for the tomatoes to grow, much longer than the maturity dates listed. I’m talking about up to 150 days from transplanting to the greenhouse to first tomato harvest, for a plant started in September. Even though the greenhouse is plenty warm, I do not add artificial light, and the fewer hours of daylight slows down the growth. For this reason, I try to plant my earlier-producing tomatoes during these months. Not only does it take a long time for the plant to grow, once the tomatoes are set it takes a longer time for them to ripen, and sometimes the winter tomatoes are a bit mealy. Still, they are tomatoes are good enough for a spaghetti sauce, tomato soup or my favorite sweet chile sauce.

Even in the summer months, the tomatoes take longer to reach maturity (first harvest) than the variety suggests, but not nearly as long as during the winter months. They really prefer being outdoors, I just can’t do it here.

One of the things I like to see when choosing tomato varieties, is those that are resistant to “blossom end rot” (BER), as I frequently find this to be a problem in my greenhouse. This is probably due to the fact that I’m constantly reusing the soil. I replenish it the best I can with compost, vermicompost, fertilizer, gypsum & eggshells (for calcium), bone meal, etc. Then, as tomatoes are growing I periodically spray the leaves with a calcium spray. With all this treatment, I still occasionally deal with blossom end rot on a plant or two.

STARTING: I always start my tomatoes in soil blocks. I start them in the 2″ size “mini” block, then usually transplant them to the “maxi” size before transplanting to the greenhouse bed. This process usually takes around 6 weeks. Occasionally I’ll plant the tomato in the the greenhouse bed directly from the 2″ block, but I find that they do much better when given time in the maxi block prior to transplant.

GROWING: While tomatoes are growing in the greenhouse, I use an organic fertilizer formulated specifically for tomatoes, and apply it faithfully according to the package instructions. I’ve gotten a few different brands and don’t really have a favorite, but I prefer using a liquid fertilizer due to its ease of use. As mentioned above I spray with calcium spray every 2-3 weeks, between the other fertilizer applications, a bit more often if I suspect BER.

I prune off the first, lowest stems before they begin to flower, to give the tomatoes plenty of airflow and up off the soil. For the determinate tomatoes, I find that winter-planted tomatoes typically don’t grow as tall, and really need this pruning. After the first crop of tomatoes have been harvested, the plant will often take a bit of a break, then I will see many new shoots coming off the plant to give me another crop. It will begin to grow every-which-way and look kind of goofy, but I will get lots more tomatoes as the plant continues to produce. Eventually, I decide I just don’t want the plant anymore, usually because I want the spot for something else. At that point, I’ll start pruning off all new growth and keep it pruned while it ripens the remaining tomatoes. Then I’ll remove the plant.

Generally I use the tomatoes to eat fresh, however I’ll often have enough to do a small bit of canning. One of my favorite things is a sweet chile sauce that I like on hamburgers, so I do a small batch of that almost every summer. Other than that, I use extra tomatoes for various pasta recipes, often in the Instant Pot.

FAVORITE TOMATO VARIETIES FOR THE GREENHOUSE

I’m kind of a tomato seed nut… I keep looking for the perfect tomato variety and am often distracted by the “bright shiny objects” seen in emails and catalogs from seed companies. Or, sometimes a variety does well once, but never again, for some reason. I’m also trying to buy more heirlooms (open-pollinated) and fewer hybrids, so I can save the seeds. Here I’ll list some of the most consistent favorites in my greenhouse. I don’t always remember to write down the day of first harvest, but “DTH” indicates Days-To-Harvest in my greenhouse, winter/summer, as I have the records.

2025 :: GROWING TOMATOES OUTDOORS

After adding a bed in a warmer location adjacent to our greenhouse, with full southern exposure and no shade, I thought I’d try growing a couple of tomatoes there in 2024. Those tomatoes did quite well, and I was able to harvest most of them before nights began to freeze. I was able to use them for a nice sweet chile sauce to can.

Since those tomatoes had been so successful, I decided to increase the number of plants in 2025 to six. This year was not so successful. I believe the biggest issue was the whiteflies which started to be a problem in the greenhouse, then migrated outdoors to the front bed.

2025 WHITEFLY DAMAGE

The whiteflies were so thick out there I just couldn’t control them. With the plants admittedly too close together and under the shade cloth, they were a bit trapped and multiplied like crazy. The shade cloth is there to protect from the intense sun, but also provides hail protection and keeps out the critters, including our ducks. However, I don’t think the tomatoes had enough airflow, and it was difficult to spray the leaves due to the cramped location. I just couldn’t get rid of the whiteflies.

The tomato damage wasn’t so noticeable the first half of the summer, and I was impressed by the number of tomatoes that were growing on the plants. The damage was much more evident later. The whiteflies damaged the leaves, which prevented photosynthesis from doing its job to mature the tomatoes. The tomatoes ripened unevenly and slowly. The vine-ripened tomatoes were blotchy (see photo below) and those yellow-green spots were hard. The tomatoes were usable for sauces after cutting off the hard spots, but lacked flavor. Many tomatoes were green or yellow-green when the freezing nights began, so were ripened indoors. These also were usable, particularly after roasting, but were mealy with little flavor. A lot of garlic, basil, oregano, sugar, salt & pepper made them worth the trouble to grow and roast them. It was kind of a headache to deal with them all.

*IF* I ever grow tomatoes outdoors again, it will only be a couple of plants, with lots of ventilation, and if I can’t control the whiteflies, I’ll get rid of the plants early rather than continue the fight.

HIGH ELEVATION NOTES FOR GROWING TOMATOES OUTDOORS

Just a couple of thoughts or observations.

Most tomato growing information will say that tomatoes will not set fruit if the plants are grown with temperatures under 55°F. None of my overnight temps are over 55°F, and I only get 2-3 nights the entire summer that are over 50°F. Yet I still see many, many tomatoes “set” on the outdoor plants.

They do ripen more slowly due to the cold nights. If your area has a bit of a longer summer and/or a bit of warmer summer nights, you should be able to grow tomatoes outdoors with no problem, assuming whiteflies or other bugs don’t bother them!

And don’t forget that “every year is different”. Some years they may do better or worse than others. To add more warmth to your tomatoes, you can plant them next to a north wall of some kind to trap the warmth from the sun. Add plastic bottles filled with water which will warm up during the day and release the warmth at night–and leave these there all summer.

Go ahead and give them a try outside! Tomatoes really prefer being outdoors, and if you can do it in you location it would be worth it.