Alaska Life

Want your own Alaska-grown tomatoes? Start now

The homegrown tomato is the Holy Grail of vegetables up here for those who have outdoor greenhouses (though this year we will see if cannabis is a competitor for the title). Unfortunately for most Alaskans, you really need a greenhouse in order to ensure that tomato flowers morph into fruits, something most tomato flowers won't do unless the temperatures are over 55 degrees at night. If not, the blossoms drop off first.

I don't want to just pander to the greenhouse owners, however. There are some species of tomatoes that are "cold hardy" and will set fruits at lower temperatures. Early Girl, Oregon Spring, Siletz and Golden Nugget are among the hybrids, but I have never had much success outdoors with these. They don't go much below 55. Still, this year may be warmer. For a bit more success without a greenhouse, try some of the heirlooms developed for cold hardiness: Glacier, Grushovka, Manitoba and Polar Baby. These definitely set fruit at lower temperature, but they really don't taste as good as the greenhouse-grown crops, in my humble opinion.

Don't forget you can grow tomatoes at a windowsill or on a warm porch.

In any case, it is time to start tomatoes. There are a couple of guidelines to follow. First, you should make sure your containers are deep enough so that roots can develop unimpeded while the first few sets of leaves appear. Three to 4 inches is a minimum for starting containers. This is the depth of recycled coffee cups, yogurt containers and the like. Yes, I used to suggest starting tomatoes in egg cartons or even half-egg shells. This is a nice novelty, but I now realize these really doesn't provide enough soil for the roots.

Next, the soil itself should be full of organic material so you can take advantage of the soil food web. The soil also needs to drain well. Compost with a bit of sand or perlite works great. There are all manner of commercial mixes available, too. I do not like those that have fertilizers in them. I can add what I want, if I want. This way I can make sure if nitrogen and phosphorus are added, it is not in quantities that prevent those all important mycorrhizae from forming.

Speaking of mycorrhizae, those helpful, beneficial partnerships between mycorrhizal fungi and roots, one species of fungus in particular, Glomus intraradices — now increasingly referred to as Rhizophagus intraradices due to better genetic analysis — has been shown to be very effective in helping its tomato plant partners. This is a very common endomycorrhizal fungi. Look for it on the label of what you buy. Heed this advice. Your aunt in Des Moines isn't getting it! You will have healthier and better-tasting tomatoes than she will.

After applying Lowenfels' Rule No.1 ("Roll seeds in the correct mycorrhizal fungal mix"), plant the seeds in the mix. Even following the rule, you might want to add some of the fungal propagules to the mixture so roots grow into them. When planting, I like to poke the seed completely into the soil, some simply seed down and then just cover with soil. In either case, the soil should be pre-dampened so seeds won't wash away at first watering. You can plant several seeds in a container and divide later.


Now make sure the soil gets warm enough. Either use a soil heating mat available at all nurseries, or place your containers on your water heater, on top of the refrigerator or in a room where temperatures are around 80 degrees. I suppose it is permissible to let your lights do the heating if they are fluorescent. Place them a couple of inches over the soil.

Soil must remain slightly damp during the entire germinating process. Place plastic wrap over the soil, but be sure to check to make sure things are not getting too wet or that seeds haven't germinated, which they will as early as five days later. Most will take a bit longer; not many will need more than 10 days. After two weeks with no results, start over.

Once your seedlings get a set or two of true leaves, it is time to move them into larger and individual quarters. These are tender seedlings. Use a fork or spoon to get under them and pop the clump of roots out. Hold a seedling by its leaves if you must. Re-plant into a preformed hole in the new container. Get some mycorrhizal propagules down there first.

A rule of thumb is 5-gallon containers for each mature plant. You can put your seedlings into big pots or gradually move them up. Just make sure the roots are never constrained until the final potting. And, make sure that you don't drown little plants by over watering their big pots.

Finally, there is the issue of light. You will get spindly plants if you use natural light. These just need to be buried deeper at transplant time. Still, they are not the best plants and don't fruit as well as those grown under good light. Come on; they're tomatoes! Invest in some sort of light system for them.

Finally, since I teased some with the mention of cannabis as a possible Holy Grail crop, they too should be started now if you want. Treat seeds like tomatoes. Note that there are all manner of studies that show cannabis plants really, really, really respond to the very same mycorrhizal fungi as do tomatoes, Rhizophagus intraradices. That makes sense since growing cannabis is almost identical to growing tomatoes. The only difference — and it is for this year only — is that getting cannabis seeds can be tricky as you cannot buy them legally yet. I will leave that to your own means, but if you get some, use the fungi. You will not regret it.

Jeff's Alaska Garden Calendar

Vegetables to start from seed: Broccoli, cauliflower, kale, cabbage, head lettuce, pepper

Flowers to start from seed: Achimenes (tuber), brachyscome (15C), dianthus (5), Stock (10L), Lockspar (20C). (Numbers are days to germinate; C means grow cool and L means seeds need light.)

Herbs to start from seed: Sorrel

Alaska Master Gardeners 2016 conference: This event will be held Saturday, April 16, at UAA's Lucy Cuddy Center. Register now. More information at

Nurseries: Visit now.

Alaska Botanical Garden: Join now. (

Jeff Lowenfels has been writing this column for 40 years and never missed a week. He is the author of the best-selling, award-winning books "Teaming with Microbes" and "Teaming With Nutrients."

Jeff Lowenfels

Jeff Lowenfels has written a weekly gardening column for the ADN for more than 45 years. His columns won the 2022 gold medal at the Garden Communicators International conference. He is the author of a series of books on organic gardening available at Amazon and elsewhere. He co-hosts the "Teaming With Microbes" podcast.