One of the more interesting characteristics of plants is that plants are affected chemically by the aroma from leaves, roots and by soil micro-organisms.

Knowing which plants like each other and which don’t, and planting these together, is what is known as companion planting.

Companion planting is the planting of different crops in close proximity of each other on the theory that they will help each other.

Marigolds are a fine example, as this plant excretes a substance from its roots which deters a number of insects. Marigolds benefits most crops, especially those in the cabbage family, as well as radishes and tomatoes. Tomatoes grow better and bear more fruit with marigolds than without them.

Drawing on my own experience, the type of marigold that seems more beneficial is the older heritage type of marigold. The best way to describe these types of marigolds is the “stinky ones”, marigolds that have a pungent aroma.

With the plant-selling season rapidly coming to a close, purchasing some marigolds and placing them around in your greenhouse may be just the “lift” your tomatoes need to produce more.

Another good candidate for companion planting is radishes. Radishes and cucumbers are another great match for companion planting. As the season progresses and you harvest cucumbers, you may be able to create space amongst the cucumber plants for a late seeding of radishes.

Radishes will grow well into September even if we do get an early frost (ugh, horrid thought).

Other interesting plant combinations are:

Beans–like celery and cucumbers; dislike onions

Peas–like carrots, radishes; but not onions, garlic or potatoes

Onions–like beets, lettuce summer savory; but dislikes peas and beans

Cabbage –likes aromatic plants, potatoes dill, onions, nasturtiums; but absolutely hates tomatoes and strawberries

Carrots–likes lettuce, radishes, onions and tomatoes; but hates dill

All vegetables like aromatic herbs such as borage, sage, parsley, tarragon, chives thyme and marjoram and oregano. Generally the more variety the better and most of these herbs thrive in greenhouses.

If you still have an empty space here and there in your greenhouse or as a result of harvesting, consider planting a few marigolds, herbs, radishes or lettuce.

Not only will you be able to extend the growing season, you’ll also bring in a world of exotic aromas, colour and texture into the greenhouse.

Ingrid Wilcox operates Lubbock Garden and Floral Consultant and offers gardening, greenhouse and flower arranging workshops. Contact her at ingrid@northwestel.net.