How to Grow Sweet Peas in a Grow Bag: The Essential Guide

The smell of sweet peas is instantly recognizable and absolutely intoxicating. These beautiful vining flowers have been popular for centuries and make an excellent addition to any garden. While it’s typical to plant sweet peas in beds with trellises, there may be situations where you’d rather plant them in a grow bag. Is this possible, and how would you go about doing it?

How do I grow sweet peas in grow bags? The trickiest elements of planting sweet peas in grow bags is ensuring that they have enough room for their roots and that they have support for their stems. Buy the biggest grow bags you can find, at least six inches deep. Then use a cane or bamboo stalk for the plant to grow up.

There are lots of advantages to using grow bags as opposed to traditional raised beds or ceramic pots for sweet peas. Grow bags are an attractive option for a number of reasons but can be a bit intimidating if you’ve never used them for something with deeper roots, like sweet peas. Follow the tips in this guide, and you’ll be smelling the amazing sweet pea scent filling your garden this spring.

Why Use a Grow Bag?

Grow bags are pot-shaped cloth bags. Once filled with dirt, the bag will hold its shape. Planting in grow bags is very similar to planting in pots but offer some unique advantages. These advantages include promoting healthier roots, better regulating temperature, and allowing adequate drainage. In a nutshell, grow bags better mimic natural growing conditions, than pots.

Root Health

In a traditional pot, roots will wind around the edge of the pot after reaching the side. This creates a tangled root system that can choke itself out or become difficult to transfer. Grow bags prevent this by a process known as air pruning.

Plant roots will naturally pull away or stop growing once they contact oxygen; this is to prevent roots from growing up out of the ground. Because the sides of the grow bag are porous cloth, enough air is let into the bag to cause the roots to stop growing at the sides rather than winding around the edge. This will produce full, healthy root systems that can support beautiful vegetables and flowers, like sweet peas.

When using a grow bag, you generally won’t have to worry about repotting or root pruning. You can simply allow a healthy root system to build out, supporting a beautiful plant.

Temperature Control

Gardening pots are traditionally made of ceramic. This material can absorb a lot of heat when exposed to the sun. The material also isn’t breathable, which traps heat inside. This can lead to rather large temperature swings between night and day. During the day, the soil inside a clay pot can get so hot that it literally cooks the plant.

The fabric that grow bags are made out of is significantly less affected by heat. The material is more breathable, allowing hot air or moisture to escape, and the surface won’t become hot to the touch in the same way. These properties allow grow bags to be significantly more weather resistant and temperature-controlled than traditional clay pots.

Drainage

When gardening, you always need to be concerned about drainage. Plants need to be watered regularly, and sweet peas are no exception, requiring heavy watering to fully bloom. However, if water is allowed to pool and buildup in the bottom of pots or beds, it can go rancid, growing mold, moss, or harboring disease.

You need a setup that will allow old water to drain so that new, fresh water can replace it and nourish your plants. Pots and even some bed setups often use cut holes to allow proper drainage. These can become clogged with rocks, roots, or other debris, becoming ineffective.

The porous sides of grow bags make them adept at drainage, allowing water to flow out of the bag from all sides. You may have to water more than you’re used to in order to compensate for the additional water loss, but it will be worth it knowing that your flowers are supplied with clean water.

Issues with Grow Bags

Grow bags are becoming more and more popular with home gardeners, and with good reason! They have some tremendous advantages and allow both novice and experienced gardeners to avoid some common missteps. However, they do have their own set of challenges and limitations that you should be aware of before you fill your first bag.

Room for Roots

Sweet peas have fairly deep roots. This is one of the main reasons why beds are the typical way that sweet peas are planted. You definitely want to make sure that you’ve got plenty of space for the roots of the plant to spread and gather nutrients. In order to ensure that your plant will have room to grow, you’ll want to get a fairly large grow bag. Make sure that you’ve got at least six inches of depth.

Stalk Support

Sweet peas are vining flowers and require some sort of trellis to support their growth. Luckily, sweet peas are not very picky when it comes to what they will grow on. You can buy a trellis, use a couple of sticks, or sink a bamboo pole into the soil. If you don’t provide something for the plant to climb, it’s never going to grow into anything particularly impressive.

Water Loss

Earlier, we talked about how well the grow bags provide drainage. The flip side of this advantage is that there is significant water loss as water will leak out of all sides of the container. You’ll have to water more frequently than what you’re used to. Setting up some sort of automated irrigation system may be in order to ensure that the flowers stay hydrated.

How to Plant in a Grow Bag

Planting sweet peas in a grow bag isn’t much different from planting in a pot. We will need to consider the unique needs of the sweet pea plant, such as it’s deep roots and need for something to climb on. Additionally, there are a few steps we’ll need to do to ensure that the grow bag is ready to go. There are two ways to plant sweet peas: from seeds and from plugs. We’ll go through both methods.

Planting from Seeds

Planting from seeds is the cheapest way to start growing sweet pea flowers. This method is also the most satisfying, as you’ll foster the plant’s growth from beginning to end. Planting from seeds does require a bit more time and effort than planting from plugs, but just follow these steps, and you’ll be enjoying a garden full of sweet peas in no time.

Plan your plant – Planting at the right time is crucial to getting a flower that will survive and thrive. In warmer regions (zone 7 and above), sweet peas can be sown in fall. Anywhere with colder winters, wait until late winter or early spring to plant.
Open the grow bag – The bag is going to be flimsy with little shape to it but do your best to unfold it to its full shape. This will make it easier to fill.
Fill the bag with soil – Fill the bag almost all the way to the top with potting mix, leaving about three inches of space between the soil and the top of the bag. Once the bag is filled, shake and loosen the dirt to fill any gaps, as if fluffing a pillow.

Soak the seeds – Soak the seeds in a small dish of water for 8–10 hours before planting. This allows the coat of the seed to breakdown faster, resulting in quicker germination. If you’re especially impatient, you can nick the edges of the seed with a knife.
Sow the seeds – Poke each seed about a half-inch into the potting mix. Then cover it in loose soil. Plant two seeds per bag.
Protect the seeds – Bring the grow bags inside a greenhouse or near a bright window inside the house. The plants are very delicate at this stage, and it’s best to allow them to germinate somewhere temperature controlled. Once the seeds have begun sprouting, you can relocate them outdoors. Try to avoid moving them after this as frequent moves can shock the plant.

Prune the plant – Once the plant is a few inches tall and has a few leaf nodes, pinch off the top of the growing tip between your fingers. You want to make this break just above a pair of leaves. This will make the plant bushier and leafier.
Nourish the soil – Sweet peas require lots of nutrition to flower abundantly. Mix your favorite blooming fertilizer deeply into the soil following the directions for how much and how often to feed your plants.
Add a trellis – Sweet pea plants require a structure to climb. If you haven’t already, place a tall climbing structure for the plants to wrap around as they grow upwards. As the vines grow, you’ll want to tie them to their trellises for extra support.

Water the flowers – Sweet peas are thirsty plants and need heavy moisture to thrive. Setting up a soaker will ensure that they grow lush and beautiful.
Deadhead regularly – Removing flowers that have wilted will extend the flowering period and keep your plants bright and colorful for longer.

Planting from Plugs

Planting from a plug allows you to skip the germination process. Although this method is more expensive, you skip a lot of the time investment and uncertainty of trying to plant and germinate seeds. Sometimes people will favor plugs for flowers that are difficult to grow from seeds or whose germination requires specific conditions. But this isn’t really a concern with sweet peas. Starting from plugs will just save you a little more time and effort while costing just a little more.

Plan your plant – You don’t have to worry as much about growing season with plugs. If the plugs are available, then they were planted at the right time already. Look for them in early spring or perhaps earlier in warmer climates.
Open the grow bag – The bag is going to be flimsy with little shape to it but do your best to unfold it to its full shape. This will make it easier to fill.
Fill the bag with soil – Fill the bag almost all the way to the top with potting mix, leaving about three inches of space between the soil and the top of the bag. Once the bag is filled shake and loosen the dirt to fill any gaps as if fluffing a pillow.

Place the bag – Set the bag at the spot in your garden where you want to grow your sweet peas. While the portability of grow bags is certainly a plus, you want to avoid moving the plants as much as possible to avoid shock. Sweet peas do best in full sun but can tolerate partial shade. Pick a sunny spot.
Plant the plugs – Press a hole into the soil with your fingers large enough for the roots of the flower, about two inches down. Widen the hole by gently circling your fingers. Place the plant into the hole and then cover the hole with loose dirt. Ensure that the roots are fully covered.
Water the plugs –Fully soak the newly planted plugs. This will help them adjust to their new environment.

Prune the plant – Once the plant is a few inches tall and has a few leaf nodes, pinch off the top of the growing tip between your fingers. You want to make this break just above a pair of leaves. This will make the plant bushier and leafier.
Nourish the soil – Sweet peas require lots of nutrition to flower abundantly. Mix your favorite blooming fertilizer deeply into the soil following the directions for how much and how often to feed your plants.
Add a trellis – Sweet pea plants require a structure to climb. If you haven’t already, place a tall climbing structure for the plants to wrap around as they grow upwards. As the vines grow, you’ll want to tie them to their trellises for extra support.

Water the flowers – Sweet peas are thirsty plants and need heavy moisture to thrive. Setting up a soaker will ensure that they grow lush and beautiful.
Deadhead regularly – Removing flowers that have wilted will extend the flowering period and keep your plants bright and colorful for longer.

Harvesting the Flowers

Once you’ve started growing sweet peas. You may want to bring their vibrant color and wonderful fragrance out of the garden and into the house. Picking the flowers at the right time can actually extend the blooming period as it prevents the plants from setting seeds. Here’s how to do it.

Pick at the right time – When there are at least two unopened flowers at the tip of the stem, it’s time to pick. This will give you the longest vase life and ensure that you keep the plant blooming for as long as possible.
Pull up at the base of the stem – It will be your instinct to grab the plant and pull down towards the ground, but this offers some resistance, and you could easily damage the plant. If you instead pinch at the base between the flower stem and the growing tip and pull up towards the plant, the flower will easily and delicately come free.
Place the flowers in a vase—Add flower food to the base water as this will extend the life of the flowers.

Repeat regularly—It’s tempting to simply leave the plant to flower, but this will shorten the flowering period. You don’t want a flash of color in the garden only for it to quickly fade away. Depending on the size of your plant, you may need to trim flowers as often as every day.

There you have it. Using grow bags will make it easy to set up your garden and keep your plants healthy. Once you’ve planted and cultivated some gorgeous sweet peas in grow bags, you can fill your life with bright and wonderfully scented flowers.