If your eagerness to grow your own herbs and vegetables is being stymied by the lack of an area that gets full sun then all is not lost. Read on for some inspiration and ideas.
Where possible thin out the canopies of nearby trees, cut off overhanging branches and reduce the height of shrubs. This can make a huge difference to the amount of sun coming into the garden. Each spring make it a routine task to get rid of the previous summer’s growth.
Soil under trees tends to be harder, often because the soil is compacted by water dripping off the leaves. Bring in extra organic material to make the soil friable, and dig deeper than normal. Beneath trees there is either dry shade or wet shade, depending on the type of tree, and this also influences how plants grow there. Where there is wet shade (which could also be caused by buildings or trees outside the yard) then mix sand and a high proportion of organics into the soil to improve drainage. Vegetables don’t like their roots to sit in cold, wet soil; this causes all sorts of problems, including damping off.
The following edibles can grow with less than six hours of sun a day. Experiment with them to see what works best in your garden.
Herbs: asparagus, celery (in temperate to hot areas), coriander (cilantro), fennel, lemon balm, mint, Jerusalem artichokes (semi shade under deciduous trees), oregano, parsley (in temperate to hot areas), rocket, rhubarb (grows tall and succulent in semi-shade, especially in hot areas), sorrel, salad burnet and watercress.
Leafy vegetables: lettuce (in particular the cut and come again varieties), kale, cabbage, oriental greens (pak choi, tatsoi and mizuna), spinach (dappled light in hot areas) and ornamental chard (and other chard varieties that are more shade-tolerant than the common Fordhook Giant).
Root vegetables: beetroot, carrots, potatoes, turnips and radishes grow better if they receive afternoon shade, especially in February, which can be the hottest month of the year. In hot summers potatoes can be grown in dappled light under trees or pergolas.
Fruiting vegetables: in very hot climates and during the hottest time of the year, capsicums (chillies and sweet peppers) do best with morning sun and afternoon shade. Generally, however, fruiting vegetables tend to require more sun, because the fruit needs to be exposed to the sun to ripen. One strategy is to train squash and vine tomatoes upwards using a trellis so that the roots are in the shade while the top growth gets sun.
Trial and error is the way to go. Try a few things and see what does well. Some plants may produce less than they would in full sun, but that is still better than no yield at all. Vegetables that are unhappy with the lack of sun will respond with lanky growth and will produce fewer flowers. They are more likely to suffer from fungal diseases if the humidity is high. These signs are messages to cut your losses and focus instead on what does well. It is not worth wasting water, plant food and effort on nurturing vegetables that are not able to respond. (Rather try growing these types of vegetable in the available sunny spots, in containers.)
Growing from seed:
Although seed can be sown in situ in shady areas, if the shade is too deep then the seedlings will be leggy. Also, in shady areas that have higher humidity, seedlings will be more prone to damping off and other fungal diseases. It is less risky to start with established seedlings, either those that you have grown in small pots or seedling trays or purchased from a garden centre.
An area that receives shade doesn’t dry out as quickly and thus needs less water. To ensure that you don’t over water these areas, push a finger into the soil to test for moisture. Delay watering until the next day if it feels sufficiently moist. If you have an automatic irrigation system then make sure the shady area is on a different circuit to the areas in full sun.
In shady areas feeding should also be less frequent because less water is being applied. Also, organics break down more slowly in the shade, which means that soil enriched with compost and other organic material will require less supplementation.
And when it’s too hot…
In gardens where there is extreme heat and too much sunlight, vegetables can be grown successfully under 20% to 40% shade cloth, however, monitoring is necessary because one doesn’t want shade when there is a succession of overcast days. This means setting up a system where it is easy to pull over or remove the shade cloth. It can be as simple as putting a pole in each corner of the bed, and securing the shade cloth to the poles with pegs (again, experiment until you find a solution that works best for you). The benefit of shade cloth is that it screens out the harmful UV rays. Humidity has the same effect, because it deflects the UV rays. This is why veggies grown in hot tropical areas experience less heat stress. Fruiting vegetables, such as tomatoes and peppers, will perform better under 20% shade cloth, while leafy vegetables can take 40% shade cloth.