I had a few failures with my vegetable planting this past year that I am hoping to rectify this year. I have wooden L-shaped planters on my deck that get 2-4 hours of sun (although it can be shady sun in some spots due to trees in my yard). I planted leeks from plants and they did not grow at all. Someone told me that if I left them in over the winter, they would come back in the spring and grow larger. Is this the case? Or is there a way I can encourage my leeks to grow? I also had a zucchini plant that only produced one flower at a time and therefore, never grew fruit. Any suggestions on pollination options? My romaine lettuce from plant was very bitter and only produced small leafs. Any suggestions on how to successfully grow romaine lettuce? Or is it normal for garden-grown romaine to taste bitter, and I should attempt a sweeter lettuce like butter lettuce? I did grow the lettuce in the same bed as spinach, and on the other end of the L-shape from oregano, basil, thyme, parsley and chives. Thank you!
Thanks for contacting Toronto Master Gardeners. I’d like to touch on some general growing requirements for vegetables and then go into more depth about the specific ones you have tried to grow.
In general, the majority of vegetables require at least 6 hours of sunlight per day — some crops, such as tomatoes, peppers, squash, zucchini and eggplant, require more for best results. They also require sufficient depth and space. Without knowing how large your planters are, but based on the fact that they receive 2-4 hours of sun per day, there will be limits to what you will be able to grow, even if you are growing in the best soil possible – i.e. rich, well-drained soil, with lots of organic matter added, such as compost or well-rotted manure.
Leeks prefer to grow in full sun, which means they need to receive sunlight for most of the day. They should be planted as deep as possible and they require a very long growing season, lots of water, and soil that has been amended with organic matter to reach their optimum size. If any of these variables are missing, the result will be small, spindly leeks. They may come back if you leave them in the ground over the winter, but in their second year they will focus their energy on producing seed, so they will go into flower rather than growing thicker in size. You may want to consider growing bunching onions instead. They require less space (you can grow them close together), can be harvested earlier, and can tolerate more shade than leeks.
Zucchini also love the sun and need at least 6-8 hours per day. They also prefer to grow in rich soil with lots of organic matter. If you are noticing very few flowers on the plant – and given your sun exposure – it is probably due to lack of sunlight if all other factors (ex. soil, water, etc.) are in check. If you have a sunnier spot in your yard, I would suggest growing zucchini in that location. You can still grow in a planter or container, but make sure it is at least 10 inches deep. Zucchini, like squash and melons, are monoecious, meaning they have separate male and female flowers. The female flowers can be distinguished by the immature fruit that sits right behind the flower; male flowers do not have this. To have successful pollination and ultimately fruit, male and female flowers need to bloom at the same time. If you don’t have a lot of pollinating insects in your yard, you can assume the role of “pollinator”. The Missouri Botanical Garden has a good photographic explanation of how to do this – Hand Pollination of Squash and Pumpkins . But again, I would consider whether zucchini is a good fit for your location and/or if you might be able to select a different location in your yard.
Of the vegetables you mentioned, lettuce has the lowest requirement for sunlight and has the best chance of growing well in your planters. It is a cool season vegetable and does not tolerate heat or drought. Heat will cause the lettuce to become bitter and will also encourage the plant to bolt, or go to seed. Last year was particularly hot/dry in most parts of Southern Ontario, so it is not surprising that your lettuce was bitter. The best time to grow lettuce is in the spring or early summer, and in the fall. You do have the added advantage of shade, which will provide some protection to tender plants in the hotter parts of the summer. When choosing lettuce, look for varieties that are described as “slow to bolt” or “heat tolerant”. Other leafy greens, such as kale, chard, arugula and mustards are also good options for your shaded area.
As a side note, if you are growing food in planters, be sure they are not constructed of older treated lumber (pre-2003) or old railroad ties, as the chemicals in both of these materials can leach into the soil and potentially be taken up by the plants.
Best of luck as you embark on another vegetable growing season!