If you’re new to vegetable gardening or expanding an existing garden, you may wonder whether cucumbers and spinach make good neighbors. Planting different crops together in the same space is called companion planting, a practice that has been done for nearly as long as humans have been growing their food.
To determine whether two plants are good companions, we need to look at both plants’ needs and growth habits. The objective here is to determine the following:
- If the two plants can benefit and complement each other’s growth.
- If they may any detrimental effects on each other.
Let’s look at spinach and cucumbers as companions and decide whether these two can share space in the garden.
The Quick Answer
Planting spinach with cucumbers is beneficial for the spinach. Cucumbers shelter the fragile greens from the scorching heat, and the two won’t compete for space because of their different growth habits. These two vegetables make good companions, especially if the cucumbers are trellised upward.
The Detailed Answer
Advantages of Companion Planting
I want to briefly touch on this concept before comparing the two veggies. Companion planting is not a new idea but a practice that has taken place for ages. When it is done correctly, it has a number of advantages, such as:
Two or more crops with different but complementary growth habits can be planted together to save space in the garden.
Some plants, such as rosemary or garlic, deter insects from the vicinity. These can help keep pests away from more vulnerable food crops that are naturally more attractive to insects.
Some crops are reputed to improve the flavor of others by proximity in the garden. Planting tomatoes with basil is said to improve the flavor of the tomatoes, making this a great partnership in the garden and on the plate. While this has not been scientifically proven, many people swear this system works!
Certain plants, such as legumes, are called nitrogen-fixers. They draw nitrogen from the air around them and process it through their roots, enriching the soil for their companions. As their root systems decay in the soil after the top of the plant is removed later, they release that nitrogen back into the surrounding soil, making it a great plant to grow just ahead of a good crop of greens or other nitrogen-hungry plants!
The Three Sisters
Some pairings only support one plant with a neutral effect on the other. Others provide significant benefits for all plants involved.
For example, indigenous tribes in the United States practiced a form of companion planting called the “three sisters.” these three plants work together in a way that enables all three to benefit. The sisters are:
- Corn: Corn stalks support the beans as they climb up, like a living trellis.
- Beans: These nitrogen fixers absorb nitrogen from the air, affix it in nodules on their root systems for later crops, and provide a secondary harvest in the same vertical space.
- Squash: The large leaves shelter the other crops’ roots from the scorching summer sun, acting as a living mulch. Squash also has prickly stems, which may help to deter animals that would devour the ripe vegetables.
Disadvantages of Companion Planting
Not all crops work together in a symbiotic fashion, though. In a bad companionship, there are several disadvantages that different crops can cause for each other.
Plants that compete for resources such as sunlight, soil nutrients, and water will result in a smaller harvest from one or both crops. Brassicas and nightshades are good examples of this. They are both heavy feeders and will compete for nutrients.
If two plants are especially attractive to the same pests, they could end up being a nuisance to each other by attracting pests that stick around and wipe out both crops.
While some companionships can be explained and backed up scientifically, others are merely a historical product of trial and error. Claims of increased yield or flavor simply by planting two varieties in close proximity are often anecdotal.
Armed with the basic foundation of companion planting, let’s take a look at our chosen vegetables and see if we can come to a conclusion on planting these two as companions.
Planting Spinach
Spring and fall are planting times for spinach seeds. This cool-weather crop doesn’t take long to mature, and it can suffer in the heat of summertime. In hot climates, you may want to try out Malabar spinach – while not a true spinach, it has a very similar flavor and is much more heat-tolerant. If you wish to stick with a true spinach variety, baby spinach leaves can be harvested about 20-30 days after sowing.
Spacing
Spinach roots don’t like to be disturbed, so it is best to direct sow them in your garden beds. Sowing spinach seeds should occur about a month before your expected last spring frost. Seeds should be direct-sown ½” deep, 1” apart, in rows 6” apart. Thin out sprouted seedlings so plants are 6” apart.
Fertilizing
Spinach is a heavy feeder of nitrogen, which means that it will need regular access to nitrogen. Before sowing, work about ½ cup of nitrogen-based fertilizer into a 10’ row. Then, fertilize every 2 weeks to keep your plants robust.
Irrigation
Spinach plants need about 1” of water per week and closer to 1½” as the weather heats up. The plants have long tap roots and an elaborate system of shallow roots. Most of the feeder roots are close to the surface of the soil, so spinach doesn’t need to be watered deeply. It thrives better if it gets the water it needs regularly.
Pests
This green appeals to pests, especially aphids, which cling to the underside of the leaves and drain them of moisture. They are also susceptible to leaf miners. This leafy green can benefit from deterrent companions like garlic, scallions, or onions.
Planting Cucumbers
Early May is typically the best time to plant cucumber seeds. Direct sowing is also recommended for these vegetables, but the soil has to warm to 60°F in order for seeds to germinate. Cucumbers are a warm-weather crop; they cannot tolerate cold temperatures. They can handle quite a bit of heat and sunlight.
Spacing
Cucumber seeds can be planted 1” deep, with each plant spaced 18”-36” apart in all directions. Cucumbers are vining plants that prefer to climb. Cucumbers will be healthiest if they are trellised. While they can grow on the ground, they are more susceptible to pests and fungi.
Fertilizing
Cucumbers are heavy feeders as well but need a balanced fertilizer. However, high nitrogen levels will fuel lots of vine development and leafy growth but not as much fruit development. Your cucumber plants will tell you if they need nutrients by leaf color. Yellow cucumber leaves indicate a nitrogen deficiency, and bronze discoloration indicates a lack of potassium.
Irrigation
Cucumbers also need about 1” of water per week. This is another reason why they make great spinach companions! Watering a dual-planted bed is simpler because both crops have similar needs.
A good rule for these veggies is to keep the soil evenly moist, so if the weather is very hot and dry, don’t hesitate to water them as needed. Drip irrigation or soaker hoses are better than overhead sprinklers.
Pests
Cucumbers are also vulnerable to insects, but not as many of the same pests as spinach (although there is one crossover). Cucumber beetles are the most prevalent. Aphids can also be an issue, specifically the melon aphid.
Our Conclusion: Cucumbers and Spinach Make A Great Pair
Spinach and cucumbers stack up as companions. Both vegetables like to be directly sown, but spinach typically goes in the ground a month or two earlier. However, this isn’t necessarily a problem, as space can be left for cucumber plants that will proliferate in the warming weather. The cucumber plants will provide shade for the spinach plants, which are less tolerant of heat.
Similar Fertility Needs
Both vegetables are heavy feeders but feed on different elements of the same fertilizer blend. Using a balanced fertilizer will give both plants what they need to survive.
The spinach will feast on nitrogen, while the cucumbers will only need nitrogen for initial vine development and then will rely more heavily on phosphorus and potassium for fruiting, flowering, and strong root support. Early in the season, you may need to apply a little extra nitrogen, but later in the season, consistent applications of a balanced fertilizer will give both plants what they need.
Complementary Growth Habits
Cucumbers like to climb, while spinach stays close to the ground. In this way, they share space well. If spinach was bothered by the cucumber’s shade, this could be an issue. However, as the hotter months approach, spinach will appreciate the respite. Some light shade prevents spinach from bolting (going to seed) too soon.
Similar Irrigation Needs
Both vegetables need about the same amount of water, so they are compatible in this way as well. Maintain consistently moist soil and amend with compost to improve the water-holding capacity. Mulch can prevent the soil from drying out and benefit both crops.
Potential Pest Problems
The only issue with this pairing is that the crops may attract similar pests. For this reason, it’s a great idea to intersperse some marigolds among the cucumber and spinach plants. Marigolds deter many harmful insects and attract pollinators like wasps which prey on those harmful insects.
Final Thoughts
Companion planting can be a blessing or a curse depending on which plants you choose to plant together. Examining each plant’s needs and growth habits should offer insight into whether or not the plants will thrive together or harm each other.
