Astrid Muschalla (Master Gardener and Coordinator of our local Master Gardeners) and Mabel Fuentes (Master Gardener in Training) shone a spotlight on the vegetable garden in July. They looked at what can still be planted, and what can be harvested, including some ideas for preservation. With veggies growing furiously at this time of year, two different strategies for pruning were highlighted. Since we so commonly grow tomatoes, this plant was discussed in the most detail including its growth habit and some companion planting tips. Astrid also shared one of her favourite perennial vegetables with year-round interest: perennial kale (Crambe cordifolia).  An approach to insect predation was shared since the insect world around us becomes very active in July, and some may be munching on your food crops. Finally, always on the lookout for organic practices for our gardens, Mabel shared a Japanese technique for sealing and preserving wood for raised garden bed construction. The blog ends with your questions.

What’s edible now?

PeasMixed salads
Chard Kale
LettuceArugula
Herbs Mustard Greens 
Young Potatoes Onions

What can you still plant? (July to September)

Beans Beets 
Mustard greensSwiss Chard 
TurnipCilantro
Lettuce Dill 
ArugulaCarrots 
Green Onions Annual flowers like cosmos (edible)

Gardener’s Notes:

Astrid uses chard like spinach in cooking. Chard keeps producing until “the snow flies”. 

Some plants, like lettuce, cilantro and dill, if planted early in April will be starting to go to seed. You can ensure a constant harvest throughout the growing season by staggering your planting (every two weeks). Plant the seeds anywhere you have a space amongst your vegetables. This way, you can have cilantro ready when you harvest your tomatoes to make salsa and dill when you are ready to harvest your cucumbers to make pickles. Astrid also freezes dill and cilantro leaves for winter use. 

Carrots can be planted until August. They need some time to develop roots before harvest.

Remember when planting seeds during these hot summer days, take care to water sufficiently.

Local suppliers of seed for fall harvest

Vegetable pruning

There are two approaches to pruning vegetables depending on what you plan to harvest. If you plan to harvest the leaves, use pruning to prevent the plant from flowering. This allows for a more abundant leaf harvest. If you are more interested in the fruit, the flowers need to stay. In this case, you may want to prune to manage the shape of your plant. This will help to maximize your harvest in a small space. Below are two examples – this graphic here is for tomatoes: 

  1. For the basil plant, the leaves are harvested. To encourage a leafy plant, prune immediately when, or before, flower buds start to form. Pinch out the growing tips, just above a leaf node (where the buds are beginning to form). This will encourage the plant to branch out to the side and grow more leaves. Flower buds on the branches should also be pinched out.  Once the buds are in flower, the plant stops growing leaves and concentrates on growing seed – so cut often to prevent this (unless you want seed 🙂 
  2. Tomato plants, on the other hand, are grown for their fruit, so the flowers are keepers. These, once pollinated, will produce the fruit. Tomatoes are a vine, and thus a sprawling plant.  Though they can be left to sprawl, to maximize your harvest in a small space, vertical gardening is recommended – so staking is helpful. You can also shape your plant to encourage vertical growth by pruning. Pruning will maximize effective plant growth by preventing overcrowding. Overcrowding compromises fruit development by limiting sunlight access to parts of the plant thus rendering them unproductive (a waste of resources). To prune, select and cut unwanted suckers. (A sucker grows in the middle of a leaf crotch (axil) and will be the start of another branch). Small, sharp pruning scissors are recommended. These are spring-loaded so that you can clip in one motion – available at Lee Valley. Tomatoes allowed to sprawl over the ground will also fruit though. To add protection for these fruit, always mulch around your plants – up to the stem but not touching it. Sometimes, chipmunks or deer may do some “pruning” for you. In this instance, you can allow the plant to grow back from those developing suckers. Astrid plans to check and prune her tomato plants once more this week, for the season. They should begin to ripen now. 

More about the tomato plant

Tomatoes have two different growth habits: determinate and indeterminate. The fruit of determinate tomatoes all ripen at once. These are preferred by commercial growers as they can all be harvested at the same time. Commercial growers pick them before they are fully ripe, so they don’t taste their best. There is nothing better than a fully ripened and freshly picked tomato from your home garden. Indeterminate tomato plants continue to grow and produce flowers and thus fruit over the growing season. They can be harvested continuously until first frost once they begin fruiting. 

What to grow with your tomatoes? Basil loves tomatoes and tomatoes love carrots, so interplanting these three plants makes for good organic practice. It provides a good natural pest control in your garden. 

Featured perennial vegetable for year-round interest – Flowering Kale – Crambe cordifolia

One of Astrid’s favourite perennials for the vegetable garden is Flowering Kale or Crambe cordifolia. In early spring, the plant starts to unfurl, and the leaves are edible. By July, it has large leaves and fragrant flowers that look like Baby’s Breath.  The flowers are edible, and the pollinators love them. Unlike annual kale, the leaves are only tasty in the spring. Once the flowers are spent, Astrid allows a few to go to seed (for collection) and cuts down the rest to allow to plant to focus energy in the roots.

An organic approach to predators

While much discussion in the mainstream gardening world has been about ridding ourselves of pests in the garden, perhaps it’s worth taking another look. The parsley worm in the photo below can be found on your carrots, dill, fennel and, of course, parsley. This two-inch-long caterpillar is not only beautiful but will turn into the black swallowtail butterfly, one of our pollinators. As we know, pollinators play a critical role in our food production. So perhaps we should make room in our gardens for some of these “pests”.

Did you know that 30% predation in a healthy plant will not significantly affect its growth? In addition, in good condition, plants can muster up an arsenal of chemicals to make their leaves unappealing to predators. Once a leaf has been tasted, the message is clear, and it is relayed through the predator community. Predators will move on, as long as there are many wild plant alternatives.   

Note that without water, it is difficult for plants to access nutrition from the soil. So, watering during drought is important to prevent stress and maintain plant resilience. 

A safe way to preserve wood for raised beds 

Many products used to preserve wood are not recommended for food gardening since they seep chemicals into your garden and the groundwater nearby. Commercially pressure treated wood should also be avoided because of the chemicals involved. While there are some safe products like Wood Bliss from Germany, Mabel shared another simple and inexpensive Japanese wood preservation technique called Shou Sugi Ban. This technique involves lightly charring the wood with a blow torch, brushing off excess charcoal and then sealing the wood with linseed oil. Charring the wood surfaces wraps the wood in a layer of carbon that’s highly resistant to mold, insects, water and even fire. Charring also destroys any existing mold. To maintain your wood, reapply the oil every 10 – 15 years.

Practical tips:

  • Lightly pass the torch over the wood
  • Focus on the parts of the wood that will be in contact with the soil as well as more porous parts of the wood, such as the cut ends. These should be darker since they will not be in contact with the air. 
  • At times, knots will release resin. This will add a sealer to the wood. 
  • If you are using the wood to build a raised bed, assemble the bed then pass the torch over the wood again, taking care not to burn it. 
  • If linseed oil is unavailable, use left-over cooking oil (from fries for example).
  • Types of wood to use include cedar and pine. Construction grade wood is less expensive than furniture grade and works well. For a more inexpensive alternative, use old wood pallet. Hemlock is another affordable option. 

Questions and Answers

What is the best approach to aphids on young apple trees? If they return, is it possible that ants are farming them?

Aphids mine juices full of carbohydrates from the apple tree. Ants (omnivorous) in turn derive their nutrition from the aphids, which they love to eat – a natural cycle at work. 

Manage this as follows: 

  • Ensure your apple trees are resilient by watering them well.  
  • Use a high-pressure hose to wash the aphids off your tree. They have a sucking straw-like mouth part that penetrates into the green tissue of the plant. Spraying dismembers the aphid, and it dies. 
  • If you are concerned that ants are farming the aphids, set ant traps at the base of the tree.  

Can you freeze basil?

Freezing is the best way to preserve basil. Dried basil has very little taste. Chop the basil leaves in a food processor. Spoon into ice cube trays with a drop of vinegar (your favourite) or lemon juice to prevent oxidization (turning grey once chopped). Top off with water and freeze. Once the basil cubes are frozen, remove them and store in sealed plastic bags. At a later date, they can be thawed and used in salads or as needed for flavour. Remember to add them at the end of the cooking process to preserve the taste. One cube is equal to about 1 to 1 ½ tablespoons of chopped basil. 

Why are the strawberries on my healthy-looking plant turning brown?

There are a number of possible reasons for this. The plants may be aborting the fruit because they are stressed (possibly by drought). Astrid currently has a similar experience with many fruit in her garden and ascribes it to this.

It is also possible that a fungus is attacking them. Hot, humid weather encourages fungal infections on strawberries. To remedy this, water the roots not the leaves. Straw mulch also helps. 

What is the best way to deal with snails and slugs in the garden eating my Hostas?

One approach is to trap slugs and snails by placing shallow containers with beer in the vicinity. The beer will attract them, they will go for a sip, and then drown in the beer. This approach requires that you monitor and refill your containers on an ongoing basis. 

You can place diatomatious earth around the base of the plant. This earth has microscopicly visible razor blade edges that will kill any soft bellied insect, including worms. However it is a broad-based approach and not recommended if you want to encourage biodiversity in your garden. 

Snails and slugs are blue-blooded and so react to copper wire. If you place a ring of copper wire around the base of your Hostas, when the snail/slug crawls over the wire, it will be shocked.

Astrid has tried all these methods but chosen to take a different approach: preventing the problem in the first place. She does this through a two-pronged approach. First, her choice of Hosta: older heirloom varieties have thinner leaves while seersucker varieties have thicker leathery leaves. Slugs and snails are more attracted to the thin leaved varieties. The second is to make her garden attractive to other wildlife that feeds on snails and slugs, such as snakes and frogs. 

Is insecticidal soap an effective treatment for insect infestation on my Hollyhocks?

Insecticidal soap is not recommended. Although it may be effective in the short term, it removes the waxy coating on the plant leaf surface. This makes the leaf more vulnerable to future infestations. A cycle of spray with a brief period of “success” followed by re- infestation of the plant and more spraying weakens the plant over time. 

Mabel’s approach is to pick off the bugs by hand. While some of plants may be eaten, if you keep on top of this task when the bugs appear, your plants will remain healthy. Remember the 30% rule shared earlier. 

Don’t  try to get rid of all your bugs, just keep an eye on your plants and remove bugs as necessary.  Remember that “bad bugs” may be food for “good bugs”, and if you remove the “good bugs” food, how will they survive? Removing the “good bugs” from your garden could lead to other problems. Everything you do in your garden sets off a wide-reaching cascade of events, so think before you act. Bug control is really a bit of give and take. 

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Happy gardening!

Reporting by Colette McKinnon, Master Gardener in Training,
Rideau 1000 Island Master Gardeners