By Valerie Barr
There is the difference between cool and warm season vegetables. All plants have an environment which they are adapted to or are suitable for. This is why we need to understand our local climate zone (zone 8) and how Climate Change is affecting our gardens. Which plants love it in the early cool part of the season and which plants love heat and need extra support to grow in our zone?
Plants have an internal way of regulating or controlling their cellular temperature and managing this control does differ between different types of plants. This concept was taught to me by a customer on Quadra 30 years ago. Simply, he showed me that by touching plants you can determine if a plant is alive or not. In the winter, living tissue or stems will be warm to the touch. When it is cold, a plant needs to be warmer than the ambient air temperature. Likewise, in summer when you touch a plant it is cooler than the air. I am sure there are exceptions to this phenomenon – some types of plants may have defenses which change their internal temperature without it being expressed externally.
How do we know when to transplant seedlings, or direct sow different types of vegetables? In February, March, and April on Quadra, the atmosphere is warming and dormant plant life wakes its energy for growing, producing new leaves and flowers. This warming air temperature, and the lengthening days, begins to warm: at first the surface, and later the deeper levels of soil. In the early part of the season when we begin to work the soil, we can find many insects and worms near the surface. During winter the insects and worms have lived deeper under the soil, protected against the cold. As the soil temperature on the surface increases, they rise. Later when the temperature continues to warm these creatures either metamorphose into their next stage of life cycle, or they go deeper into the soil to avoid the dry warmth of summer. In winter, vegetables still growing in the garden maintain a cell temperature warmer than their surroundings. When you harvest in winter, you often find non-dormant bugs and slugs keeping warm and feeding, wrapped inside the plants’ outer leaves.
It is important, when we plant our new veggies, to understand what soil temperature is needed to keep them growing and healthy, encouraging strong root development. Of course, there is always the chance of a late frost actually killing or stunting your lovely new plants. I use night time temperature to gauge when it is okay to put seed in, or to plant out our precious seedlings.
I know from years of putting down grass seed that it needs a night time temperature of 6C for it to germinate, which normally takes 10 days. I have prepped and seeded lawns in mid April and then had a few nights of frost, and yet because it was also very dry the seed was not damaged. After the frost the grass would germinate slowly but satisfactorily.
For cool weather crops, for example Arugula, Broad Beans, Peas, Kale etc. a night time temperature of 5C is probably okay to seed or transplant outside, knowing that we will still have nights that drop down to 0C or below. This Spring I transplanted peas which I had started inside, then we had frost and even snow. I had them under a cloth tunnel and on the coldest nights I threw a tarp on top for extra protection. It was extra work daily, just for the earliest pea pods – what was I thinking? Before it was much warmer than 5C at night, I planted out winter leeks which are cold hardy, and then the summer onions followed the leeks by two weeks. Lettuce is also a crop that prefers cooler temperatures and can be planted or direct seeded when it reaches between 5 and 7 night time temperatures.
For warm weather crops, for example Tomatoes, Peppers, Eggplant, Basil, Cukes, Squash, Beans, and many more, the night time temperature should be 9C unless you put covers on them to protect the plants from chilling soil temperatures.
Many gardeners are uncertain when to plant certain types of vegetables, although their plants often succeed despite cooler temperatures. It is very tempting to plant something that you have just purchased in April. Often commercial greenhouses are managing their growing space and getting plant products out their doors quickly to make room for the next crop to be started. Even though you can buy tomatoes in April, it is too early to plant them in your garden unprotected.
Climate change is evolving our timing to plant the warm season garden. As I write this Blog, we have just hit 8C at night on May 8th. Where it would be normal to plant tomatoes in late May and early June, Grant is putting them in the ground now, but building a protective shelter over them for at least the next few weeks. The scary part of the warm nights this early is that it is continuous for several weeks ahead and not just an anomaly. Where this helps us grow an earlier season garden, it also causes worry about water supply and the drying out of our forests. Even if we get rain later will it penetrate the canopy of the trees to keep the undergrowth moist?
Sharron Hatelt of Heriot Bay has managed a volunteer weather station for Environment Canada’s atmospheric observations for 35 years. She has kept and reported continuous data on rain measurements and temperature readings for all those years. Wanting to make sure that a change in our Spring weather over the last 10 years was not just my imagination, I contacted Sharron to get clear details on our local weather. She kindly explained how to look up the records on Environment Canada’s website. I analyzed the stats for the last 20 years in May, the month when traditionally most of our gardens are planted.
Prior to 2013 the average low in May was between 6.5 and 7.7C, with a few warmer years scattered in. Since May 2013, the average lows are between 9 and 10C, with scattered drops below 8.6C. This does show a change in climate for the last 8 years. The other important stat is the date when these night temperatures reach 9C continuously. Since 2013 those first dates in May have been from May 5th to 18th : predominately in the first and second week of May. Prior to 2013 the 9C nights began most often during the third and fourth week of May.
Sharron explains that for her, the rainfall levels are more pertinent for her observations – saying “I noticed a trend in the last 10 years of decreasing annual rainfall. While the average rainfall was 75 inches for the first two decades of my records, we have steadily been decreasing in the average, so now it is 65 inches. A drop of 10 inches is significant I think. The gradual warming of 2 degrees, give or take, I have noticed within the last 3 years. This applies not only to the increase in the high temps but also to the low temps as well.”
This change means that we can, with care, plant our warm weather crops earlier, if we are watching the forecast for night time temperatures after the first week of May. Sharron is also suggesting that we will have drier times ahead if the rainfall stats keep lowering. These weather stats are published by Sharron: monthly on the Corkboard/Facebook and quarterly in the Discovery Islander.
Starting Basil, Zucchini, Winter Squash, and Cucumbers
I started Genovese Basil on May 3rd in one large flat from which I will transplant directly into the sunniest part of the garden. Basil is definitely a warm weather herb. It is always one of the last seeds I start so I am not tempted to plant it out too early. We make pesto for the freezer and so choose Genovese which we harvest in the heat of August. I like to let the leaves warm in the sun before picking it in the early afternoon – processing it when I think the highest flavour is in the leaf. I remove the leaf from the stem and check for the unwanted protein of insects. Then without washing the leaves, I chop it in the food processor with olive oil, lots of garlic, nuts, and a cheese substitute since I am lactose intolerant. Into the freezer it goes in small containers with a top layer of olive oil to protect it from freezer burn. We love eating pesto on pasta in the winter when the flavour of summer is so welcome.
Zucchini is a seed we have to use sparingly as we know that summer heat can produce prolific fruit. While you can direct seed in the garden, I find it easier to start 2 seeds in a 4” pot in the house. Then I can watch the germination progress. Zucchini is a summer squash that forms a bush – we use an heirloom variety called Black Beauty which grows about 24” tall. They seem to do well in any part of the garden and are not a fussy plant. Even if we are carefully harvesting, we will miss a fruit or two and we then end up with monsters. If we can not give the monsters away, I chop them in the food processor and freeze them in baggies for winter use in soups, stews, or spaghetti sauce.
We grow as many Winter Squash as we can squeeze into the garden and it is always the last vegetable to be planted. I start them 2 seeds in each 4” pot. Since they are not in their pots for a long time, I find the two plants separate easily. I plant them back to back if they are a vining variety or 4 feet apart if they are a bush variety. If you want to control the direction of the vine, a little trick is to plant the seedling with the second true leaf pointing in the direction you want the vine to grow. I plant each different variety as far apart as possible, since they can cross pollinate as the bees move from plant to plant. If planted too close together we may end up with some weird hybrids which is not our goal.
The following five types are the Winter Squash we like the most (all from West Coast Seeds):
The two bush varieties I started on May 8th are Gold Nugget and (bush) Delicata. I am not sure if the Gold Nugget will germinate since the seed is old (2015) but it is worth a try since they are lovely. We like this early small squash, and eat it up – they don’t seem to last long enough to store for later. It is an 85-day variety measured from when you transplant until when you harvest. The Delicata is a popular, good winter storage variety that is small enough for one meal. They keep very well through the winter stored in an unheated room in our house.
Grant’s favourite squash is Burgess Buttercup which has a rich and flavourful dark orange flesh. The longer you store it the sweeter it becomes. It is definitely a rich variety for making soup. Each squash is large enough for several meals and the weather in 2019 rewarded us with many fruit on each vine. We also grow a buttercup squash called Waltham that looks just like a butternut. The flesh is a deeper orange than a butternut but I can not taste a difference in flavour. Waltham is a prolific producer and stores well over winter. Both of these buttercups are large vining plants and need enough space to grow.
Vegetable Spaghetti Squash has a different structure/texture and taste from other winter squash. They are moist and succulent. I bake them and then with a fork remove the spaghetti from its shell. We eat this squash by itself as a side dish, or as spaghetti for whatever sauce we make – pesto or tomato or curry.
Finally, I have started pickling cukes and have used the variety Homemade Pickles from West Coast Seeds. I started 6 plants at the same time as I started the squash and will transplant them as soon as possible into the sunniest part of the garden. I have a friend who grows pickling cukes and when she is finished canning she gives me her extras to fill out what we need. Grant loves dill pickles which are very easy to make. I don’t bother with other cucumbers because there is so much else to eat then.
Update on Previous Posts
The seedlings left under the grow lights now are Basil, Squash, Brussels Sprouts, Kohlrabi, and Pickling Cukes. These are all warm season crops, and since the recent weather is so ideal we will plant them out as soon as they are hardened off.
Grant has planted his tomatoes under an elaborate moveable glass protection that he had fun building. This year the tomatoes are a unique selection of this and that gifts from friends and store-bought varieties. We did not find exactly what he was looking for so have ended up with an interesting group: more cherry tomatoes than normal and I am thinking I will dry them as we harvest.
My snap peas have flowers and we should be eating them in ten days. After several months of delicious kale salad the plants have wilted and are finished. The bees are still loving the flowers though so we will leave them in the ground until they have dropped their seeds. Usually just the purple Russian kale reseeds and it does move around a bit. The seed dropping now starts plants right away and we select which ones to keep depending on where they end up. The red leaf mustard is doing well and we are eating it daily with mixed greens. The lettuce will be ready to eat soon.
Of course, it is a busy time with lots of weeding to be done. I like to keep on top of the little seedling weeds which are much easier to remove when they are small. We have not had to water in weeks with the well spaced rainy days. I have lots of transplanting to do and will get on it during the long weekend.
Next Post I will explain what seeds are direct planted in the ground in May. Grant still has carrots and beets as well as the bush and pole beans to plant. And don’t forget the corn.
Grant Hayden and Val Barr are happily retired to play in their garden as they like. Val worked in horticulture for almost 45 years and started her first food garden at 18. Grant grew up as a prairie farm-boy and his last occupation was in forestry. He has planted thousands of trees and cut quite a few down as well.