Fortunately, our growing season and summer temperatures in the interior of Alaska are more than enough to grow most types plants. While it doesn’t usually get exceptionally hot, the interior does get a fair bit of warmth, sun and otherwise great gardening weather. You won’t be growing outdoor pineapples here, but even some warm climate varieties of peppers and tomatoes will do well here.
Have A Plan For Dealing With Our Short Growing Season
By most gardeners standards, our last frost date within interior Alaska is usually around May 25th to June 1st. You might see estimates as early as the 2nd week of May, but these are always at risk in a cold year. Most Interior Alaska gardeners use June 1st as their last frost date.
Our first frost date is usually recognized as September 1st. Some years will see a frost later, others will come a bit sooner. It’s important to remember that these are averages and you need to keep a good eye on the weather around these dates.
But it’s also not quite enough time for most garden plants to be grown directly from seed. What this means is that you have little choice but to prepare most of your garden starts indoors. You can also look into winter sowing techniques for cold hardy vegetables, which allows you to plant your garden starts outside.
There are only a handful of plants that can be direct-sowed and will be successful. You can find these direct sown plants on our seeding schedule.
When To Get Started On Your Subarctic Garden
If you read through our blog, you can see that we begin our gardening season in March. Obviously it is way too cold for any plant to survive, as we’re often still in below zero temperatures at this time. We have a rather aggressive seed starting schedule that ensures we’ll have everything ready to plant outside around the last frost. This schedule is important to follow to make sure the plants are the correct size and are also manageable. Indoor garden space is often at a premium, so following the planting schedules is important.
Using a greenhouses for raising garden starts is also particularly tough in the interior of Alaska. It’s not uncommon for us to have negative temperatures in March. Those temperatures, in a greenhouse, are extremely costly to heat against. It’s much more practical to grow your garden starts indoors. A greenhouse is still valuable, though. You can use it to transfer your plants outdoors when it’s much more reasonable to heat, or when the plants can survive the outdoor temperatures on their own.
Alternatively, you can buy garden starts from many nurseries here in town and they are geared up to support you. This is certainly the easier of the two methods of getting plants, but also far more expensive. That said, for a lot of people, this is the better choice.
Hardening Off Your Plants
Usually in April and May, we’re rather busy with trying to harden off our plants. This involves introducing them to the sun’s intensity a little bit at a time.
When you raise plants indoors, the transition to the sun’s intensity can be quite intense for the plant. The sun is several magnitudes stronger than any grow light you could possibly buy. If you just put everything outdoors at once, chances are good your plants will die.
The hardening off process happens over the course of a week (or more) where we’ll bring them outside for an hour, then a couple of hours and so on. We do this until they’ve built up enough protection from the sun, which usually takes about a week. Remember, though, that this time is still well at risk for frost, so you can’t just leave everything outside.
It’s also usually best in the very early stages of hardening off to pick cloudy days so the plants don’t have to experience the full power of the sun. Also, avoid putting your plants outside when it’s particularly cold (and certainly near freezing) or when the weather is poor.
You can consider leaving some of your cold hardy and frost tolerant plants outside once May comes around. If freezing temperatures are predicted, we recommend bringing your plants back inside or in the greenhouse. For warmer weather crops, however, we recommend keeping these indoors at night until we are past our last frost date.
Acclimatizing Your Plants To The Subarctic
In the subarctic, the hardening process also involves acclimatizing the plants to our cooler evenings. Frost is not the only enemy to many plants, so can relatively cool evening temperatures. A large temperature swing to cooler temperatures can cause shock to plants which will harm growth.
Once the plants are hardened off, we use a small, temperature controlled greenhouse in May. This gives us flexibility because usually our indoor space is literally exploding from plant growth. We also use this to allow the plants more slowly acclimate to temperatures much cooler than they experienced indoors. Most importantly, it gives us the ability to have our plants outside even when frost is still a risk.
About mid May and beyond, we like to have our plants outside for both day and night when we can. We’ll only do this, though, if we are absolutely certain that the forecast will not bring about frost in our area. If there’s any risk whatsoever, usually below 38 degrees, we’ll just keep them in the greenhouse or inside.
When we plant into our garden, our starts are fully acclimated to the sun and our climate. This means they will be healthier, sustain less shock and will be ready to set roots.
Figuring Out When To Plant Your Garden In Alaska
Some plants are rather frost tolerant and can be planted quite early in the season. In early to mid May, you can start thinking about planting potatoes, radishes, kale and a few other varieties that will deal well with the cold. Our seed schedule list identifies all the cold hardy plants.
For the majority of your garden, though, definitely wait until dangers of last frost have cleared. Pay attention to the weather and once evening temperatures are steadily above 45 degrees, that’s when it’s usually safe to plant your garden. It’s still possible to get late frosts, so just be careful!
Warm climate and frost sensitive plants, such as tomatoes and peppers, are often best treated with a little more patience. Tomatoes can often go outside after the danger of frost has cleared, but low temperatures are still in the mid 40’s. Peppers, however, should be kept inside overnight until evening temperatures are at least 50 degrees.
The point at which you head out to plant is a very careful and calculated decision. Again, last frost could be anywhere from the second week of May to June 1st, or even after that! We’re eyeballing the weather and evening temperature forecasts at this time to see if we can get in there early. Early planting will give you an edge, but if you make the wrong decision, it could also wipe out your entire garden in one night.
If you really want to play it safe, take June 1st or even June 5th as your planting date. This is usually a no-risk time frame, but you should still be keeping an eye on the weather.
Learn How To Force Your Garden To Maturity
Many plants can be “forced” into maturity and using those techniques will benefit your harvest,.
For example, with Brussels sprouts, it is imperative to top the plant about a month before your first frost. Similarly, you’ll want to top indeterminate tomatoes around the same time and trim away much of the foliage. This will force these plants to produce your desired product, ripe tomatoes and fully formed Brussels sprouts.
You can also help plants along that need pollinators to be productive. For tomatoes and peppers, this is really easy. Simply tickle the flowers every day or two and this process will virtually guarantee a pepper or tomato will grow.
Other flowing plants, such as cucumbers and squash, are a little more difficult to pollinate by hand. These plants feature male and female flowers. As you might imagine, the male flower has to pollinate the female flower. This can be done by hand to help your plants along.
Always remember, the frost is coming and your plants don’t know it. Help them along with a few drastic measures.
Figuring Out When To Take Down Your Garden
The first frost is usually something you have to keep an eye on. Often times, there are warnings in the local paper and other news sources that frosts are inevitable, which means it’s time to start taking down your garden.
Last frost is flexible, mainly because there isn’t imminent risk of extremely cold temperatures just yet. The danger is frost, which will kill a lot of your garden’s plants. We take advantage of this flexibility and harvest our garden in multiple phases.
Shortly before the first of September, you really need to be thinking about harvesting everything that is mature for when a frost settles in. If your garden is particularly large like ours, you also have a lot of work to do with preservation. The point is to try to get ahead when you can because there will quickly be that time when outdoor growing is done here and everything will die.
We prioritize our harvest based on hardiness. We start with our warm loving plants as well as those that are frost sensitive. We will often leave our frost tolerant and cold hardy plants for harvesting after the frost.
Harvesting Your Cold Climate Garden In Phases
The first thing we harvest is always our warm weather vegetables. We’ll usually harvest tomatoes, peppers and eggplants just before first frost, no matter the color. We usually try to ripen these as much as we can indoors so we maximize our harvest.
From there, we like to get our squash and cucumbers harvested. These plants are not frost tolerant. The first frost will kill the plant, but it won’t destroy your harvest. That said, you need to harvest these things preferably just before the first frost or immediately after the first frost.
If one or more of your frost sensitive plants needs a bit of extra time, you can often times throw some frost cloth over them and get another week or two of growing time. This is great when you’re really trying to push our season to the edges and for things like squash that often need just a bit more time.
Some things can be left well into the first few frosts. Most root vegetables are quite frost tolerant. As are kales and most brassicas. Carrots will even improve their flavor if left to experience a few frosts. The important thing is to get all the garden harvest and chores done before the real cold moves in!
Learning these complexities is what gardening is all about. Gardening in the sub-arctic is a challenging and fun thing to do.