Tomatoes and sweet potatoes are two delicious and easy-to-grow garden staples. But can you grow them together, or are they best kept in separate areas? Many varieties of different plants can be grown in the same garden, provided you have enough space, but not all plants grow well as close neighbors.
Some plants grow really well together and can even benefit each other. Companion planting has been practiced for generations. Companion plants benefit their neighbors by improving the soil conditions, providing a service like shade or support, attracting pollinators, or repelling pests. It’s always a good idea to learn about companion plants as a potential way to improve the health and vitality of your garden.
Some other plants, however, are best kept away from each other. If two plants are both heavy feeders, they will directly compete for soil nutrients. Vigorous vines can easily shade and outcompete close neighbors. Other plants may attract the same pests or be highly susceptible to the same diseases and should be grown in separate areas of the garden.
One of the best things about gardening is that there’s no absolute right or wrong way to do it. Anyone with a sunny location can grow some garden plants, even if the space is as simple as a sunny balcony or deck. The larger your garden, the more plants you can grow, but don’t let limited space stop you from gardening.
Both tomatoes and sweet potatoes can be easily grown in containers, as well as in more conventional gardens. Let’s now take a closer look at these plants, what it takes to grow them, and whether or not you should grow them together.
The Quick Answer
It would be best not to grow tomatoes and sweet potatoes together. These two plants are both susceptible to some of the same common diseases, such as potato blight and bacterial wilt.
Grow these plants in separate areas if possible, and don’t grow them in the same places each year as that can also help spread diseases. Taking a few simple precautions can help you grow the healthiest plants possible and enjoy healthy harvests.
The Detailed Answer
There are plenty of plants that grow well with both tomatoes and sweet potatoes, but these two plants should be grown separately. Tomatoes and sweet potatoes are both highly susceptible to some of the same bacterial and fungal diseases, and one infected plant can quickly spread the disease to any nearby healthy plants.
To complicate matters, many pests and diseases can linger in the soil for one or two years after initial infection. Therefore, it is wise not to plant tomatoes, peppers, potatoes, or sweet potatoes in the same garden area any sooner than a 3-year rotation.
All of these plants can spread some of the same diseases to each other, either through close contact or through contaminated soils.
Both tomato and sweet potato plants thrive in very similar conditions, however. If you have ideal growing conditions for one, you can easily grow the other, provided that you have enough space. Both tomatoes and sweet potatoes thrive in full sun and a warm climate.
They both need rich, moist, well-drained soil. They both benefit from the addition of organic compost at planting time and during the growing season for an extra boost in nutrients to provide plenty of fruits and roots to harvest.
As you plan your garden, you can easily incorporate tomatoes and sweet potatoes, just not in the same bed. Learn how and when to plant them and what they need to thrive. Prepare your garden plot well in advance and provide ideal growing conditions.
Try growing them each with some companion plants that with help them along. Most of all, have fun with your plants. Try growing something a little different, and you might discover a new favorite summer garden veggie.
Tomatoes
Once you have enjoyed eating a garden-fresh tomato, you will never want to eat a store-bought tomato again. Tomato (Solanum lycopersicum) is an annual fruit-bearing garden plant that is easy to grow, delicious, and worthy of a sunny spot in any garden.
Many tomato plants are tall and sprawling “indeterminate” varieties, capable of producing tomatoes throughout the hottest summer days and until the first frost.
Other varieties of tomato are “determinate” and will produce one large mid-season crop and then die back. If you have limited space or want to try growing tomatoes in a container, look for a compact dwarf variety that will stay small and bushy.
If you are willing to try starting tomatoes from seed, you will be amazed by the vast number of varieties available for the adventurous gardener.
You can enjoy small, medium, or large-sized fruits. Check out a rainbow of multicolored fruits, including red, orange, yellow, green, bronze, and striped! You will find tomatoes ideal for canning or slicing, and others perfect for eating fresh off the vine.
Sweet Potatoes
Sweet potatoes are fun and easy to grow. Sweet potatoes are not grown from seed but from “slips.” A sweet potato slip is a young vine start that you can buy online or from a garden center or start your own from a store-bought sweet potato!
Unlike regular potatoes, sweet potatoes (Ipomoea batatas) are related to morning glories. A single sweet potato vine will easily grow 6 to 10 feet long and can develop anywhere from 3 to 10 sweet tubers underground. Sweet potatoes are orange and fleshy and can be cooked into many tasty dishes.
To minimize diseases lingering in the soil, allow at least 2 years between planting sweet potatoes, regular potatoes, tomatoes, or peppers on the same plot of land.
Sweet potato vines can grow quite long and vigorous, but they grow readily in pots, raised beds, and traditional garden rows. The vines are attractive and often grown as ornamental annuals cascading over the edges of large pots.
Companion Planting
Interplanting, or companion planting, is the use of one plant to benefit another. Companion plants can provide structural support or shade, help with weed suppression, break up hard clay soils, or fix nitrogen into the soil and make it more available to other plants. Companion plants can also attract pollinators and deter pests, helping other plants grow better and produce more fruits.
Both tomatoes and sweet potatoes have many companion plants that will help them grow. Plants like peas and beans are legumes and enrich the soil, benefitting other plants. Some heavily aromatic plants like basil and marigold can help repel pests.
Other plants like yarrow and parsley are pollinator favorites and attract a multitude of beneficial insects. Grow an assortment of different companion plants throughout your garden, and many other plants will benefit as well!
| Tomato Companion Plants | Sweet Potato Companion Plants |
| Basil | Basil |
| Borage | Beans |
| Calendula | Chives |
| Dill | Dill |
| Garlic | Garlic |
| Nasturtium | Marigold |
| Onion | Nasturtium |
| Parsley | Peas |
| Thyme | Yarrow |
Timing of Planting
Both tomatoes and sweet potatoes are warm-season annual crops and will grow throughout the summer and until the first frost. Since you won’t be growing these two plants in close proximity, you don’t have to worry too much about coordinating the planting times. Ideally, put your plants out on an overcast day to help minimize transplant shock.
Tomatoes can be planted outside after the last frost date when the soil temperature has reached at least 60 degrees. The ideal growing temperature for tomatoes is anywhere between 65 and 85 degrees. If you started tomatoes indoors, take several days to harden them off to help transition them to outdoor growing conditions.
Sweet potatoes can be planted outside when the soil temperature has warmed to about 60 degrees. These plants like it hot and will happily grow in temperatures ranging from 65 to 95 degrees. Water them well after transplanting and keep the soil moist so your plants can adjust well to their new growing conditions.
Gardening Style
You can grow tomatoes and sweet potatoes in many ways. If you have a garden laid out in rows, you can easily grow these plants in separate rows. If you have raised beds, grow them in separate beds. If you are container gardening, grow a compact tomato plant in one pot and a sweet potato plant in another pot.
General tips for growing success:
- Start with high-quality, well-drained soil.
- Grow your plants in full sun.
- Keep the soil moist
- Keep your garden well-weeded.
- Add nutritious compost to give plants the energy they need to grow and thrive.
- Observe for signs of pests and diseases.
- Rotate crops to minimize soil contamination.
- Destroy, don’t compost, any diseased plant material.
- Mulch around plants to improve soil conditions.
- Attract beneficial insects.
- Give your plants plenty of space to grow.
Ideal Growing Conditions
| Tomatoes | Sweet Potatoes | |
| Light | Full sun, at least 8 hours of bright sunlight per day. | Full sun, at least 8 hours of bright sunlight per day. |
| Water | Consistently moist soil. Average 1 to 2 inches of water per week. Uneven watering can cause fruits to split. Do not over-water or allow soil to stay wet. | Consistently moist soil. Average 1 to 2 inches of water per week. Uneven watering can cause fruits to split. Do not over-water or allow the soil to stay wet. |
| Soil | Rich, loose, well-drained. | Rich, loose, well-drained. |
| Nutrients | Add organic compost at planting time and again mid-season when plants begin fruiting. | Add organic compost every month after transplanting. |
| Mulch | Mulch around plants to retain soil moisture, enhance soil nutrients, and protect against some pests. | Mulch around plants to retain soil moisture, enhance soil nutrients, and protect against some pests. |
| Space | Allow at least 12-18 inches of space between each plant. Compact plants can be grown slightly closer together than full-size plants. | Sweet potatoes are vigorous vines and require a lot of space. Do not prune your vines to keep them compact, they need the energy from the leaves to produce healthy tuberous roots. |
| Support | Grow tomatoes with a tomato cage or train to a stake to keep them upright, save space, and keep fruits off the ground. | Sweet potatoes do not need support. The vines are not climbing and do not have tendrils, so they will sprawl along the ground. |
| Season | Tomatoes are sensitive to cold and grow during spring and summer, fruiting from summer until fall. | Sweet potatoes take a long time to grow and require a relatively long growing season. |
| Harvest | 60-100 days from seed. Tomatoes can be harvested throughout the growing season. | 90-120 days from transplanting slips. Sweet potatoes are typically harvested once, when potatoes have reached the desired size. |
Common Pests
One of the most common pests of the tomato plant is the tomato hornworm. These giant green caterpillars quickly eat one leaf after another. Fortunately, hornworms are easy to spot, easy to identify, and easy to remove (they are harmless to humans).
Other pests to watch out for include flea beetles, which create numerous small holes in the leaves, and aphids and thrips, which suck plant juices with their tiny piercing mouthparts.
Because sweet potatoes grow underground, there are many pests that cause damage to their roots. Potato weevils, grubs, and wireworms all bore into the fleshy roots and can cause extensive damage. Above ground, you may see flea beetles or cucumber beetles, both of which munch on leaves, creating numerous holes.
Try to give your plants the best growing conditions possible so they are healthy and resilient. Some pests can be prevented or minimized by using floating row covers, planting pest-repelling companion plants, and practicing crop rotation.
If you do notice insect pests, try to remove them without using insecticides because insecticides harm beneficial insects as well as pests.
Final Thoughts
Growing both tomatoes and sweet potatoes can be a very tasty, prolific, and rewarding experience. These plants love the warmest summer weather and thrive in similar growing conditions. Tomato plants will provide you with fruits throughout the summer and until the first frost, while sweet potatoes will yield one larger late-season harvest.
But since these plants can share many of the same pests and diseases, be sure to give each a separate space in the garden. Give your plants plenty of space, full sun, and rich, well-drained soil. Rotate crops yearly and try companion plantings with beneficial partners to maximize crop vitality.
