Discover How Fast Sunflower Seeds Grow in Gardens

When I first started gardening, I was curious about how fast sunflowers grow. I mean, they seem to shoot up so quickly, and I wanted to know if I could get a good harvest of seeds in a single season. It turns out, there’s a lot that goes into it, from when you plant them to the type of sunflower you choose. I’ve learned a lot about getting those fast-growing sunflower seeds to produce for me.

Key Takeaways

• Sunflower seeds typically sprout within 7 to 10 days after planting.
• The main growth spurt, where the stem and leaves develop rapidly, happens between 20 and 60 days after planting.
• Buds usually start forming around 60 to 80 days, leading to full blooms typically between 70 and 90 days.
• Sunflower seeds are usually ready for harvest about a month after the flowers fully open, often in September.
• Variety plays a big role; some sunflowers mature in as little as 55 days, while giants can take up to 120 days.

Why Sunflower Seed Growth Speed Matters in Your Garden

When I first started gardening, I was focused on getting things to grow fast. I wanted to see results quickly, you know? Sunflowers seemed like a good bet because they get so big and look so cheerful. But how fast do they grow from seed? It’s not just about planting and waiting; understanding the growth speed helps me plan my garden better.

Knowing the timeline for sunflower growth is pretty important for a few reasons. For starters, it helps me figure out the best time to plant them so they have enough time to mature before the first frost hits. If I plant too late, I might miss out on those big, beautiful blooms and seeds. Plus, if I want to have sunflowers blooming for a long stretch, I need to know how long each variety takes and maybe try planting them at different times. It’s all about timing to get the most out of my garden space.

Why Growth Speed Matters

• Planning your garden layout: Knowing how quickly sunflowers grow helps me decide where to put them, especially if I’m planting them alongside other vegetables or flowers with different growth rates.
• Succession planting: To have a continuous display of blooms or a steady harvest of seeds, I need to stagger my plantings. Understanding the growth cycle of different sunflower types is key to this.
• Maximizing the growing season: Sunflowers need a decent amount of time to develop. Planting them at the right time ensures they have the best chance to reach their full potential before the weather turns cold.

It’s easy to get caught up in the excitement of planting seeds, but a little bit of knowledge about their growth speed can make a big difference in the outcome. It’s like knowing how long it takes for a cake to bake – you don’t want to pull it out too early or leave it in too long.

What to Expect

I’ve found that different types of sunflowers grow at different paces. Some are bred to be quick bloomers, while others take their sweet time. It’s not just the variety, though; things like soil quality, sunlight, and water can also affect how fast my sunflowers shoot up. I’m always looking for ways to give them a good start, like making sure the soil is just right before I even put the seeds in the ground. Getting that initial soil preparation done properly sets the stage for everything that follows.

Key Factors Influencing Growth

• Variety: Some sunflowers mature in as little as 55 days, while others can take up to 120 days. This is a huge difference when you’re planning your garden season.
• Sunlight: Sunflowers, as their name suggests, need plenty of sun. At least 6-8 hours a day is usually recommended for optimal growth.
• Water: Consistent watering, especially when they are young, helps establish a strong root system, which is vital for fast growth.
• Soil: Well-drained soil with good nutrients is best. I usually add some compost before planting to give them a boost.

When to Plant Sunflower Seeds

When I think about planting sunflowers, the first thing that comes to mind is timing. Getting this right is key to understanding how fast sunflower seeds grow and when I can expect those cheerful blooms. Sunflowers are heat-lovers, so I always wait until all danger of frost has passed and the soil has warmed up. Ideally, the soil temperature should be at least 60°F. This usually means planting sometime in April or May, depending on where I live.

I have a couple of options for getting my sunflowers started:

• Direct Sowing: This is the simplest method. I just poke a hole about 1 to 1.5 inches deep, drop in a couple of seeds (just in case one doesn’t sprout), cover them up, and that’s it. If both seeds germinate, I’ll thin them out later to leave just one strong seedling per spot. I space them about 6 inches apart for smaller varieties and up to 12 inches for the taller ones.
• Starting Indoors: Sometimes, especially if I’m worried about birds or other critters getting to the seeds, I’ll start them indoors. I use biodegradable pots so I can plant the whole thing later without disturbing the roots. Once the seedlings are a couple of weeks old and the weather is right, I’ll gradually get them used to the outdoors before transplanting them. This can give me a bit of a head start on the growing season.

To keep the blooms coming all summer long, I also practice succession planting. This means I plant more seeds every two to three weeks. It’s a great way to ensure I have sunflowers at different stages of growth, from early summer right through to fall. It helps answer the question of how fast sunflower seeds grow because I can see the progression over a longer period.

The timing of your planting directly influences the germination speed and the overall growth rate of your sunflowers. Waiting for warm soil is the most important factor for quick sprouting.

Germination Stage

Once I drop my sunflower seeds into the soil, I always wonder how long it will take before I see those first little sprouts. It’s a pretty exciting part of the process. Generally, sunflower seeds are quite eager to get going. I typically see germination happen within 7 to 10 days after planting, assuming the conditions are right. This is when the seed coat starts to split, and a tiny root emerges, anchoring itself in the soil. It’s a delicate stage, and I try not to disturb them too much during this time.

Here’s a quick look at what happens during germination:

• Moisture: The seed absorbs water, which softens the shell and activates the embryo.
• Temperature: Warm soil temperatures are key for quick sprouting.
• Oxygen: The seed needs air to breathe and begin its metabolic processes.

It’s fascinating to think that all the potential for a towering sunflower is packed inside that small seed, just waiting for the right signals to start growing. I find that keeping the soil consistently moist, but not waterlogged, really helps this initial stage along. It’s a simple step, but it makes a big difference in how quickly those first leaves appear.

If I’m starting seeds indoors, I’ve noticed they can be ready to transplant in less than two weeks. It’s important not to leave them in their starter pots for too long, as their roots grow fast and can become cramped. Getting them into the ground at the right time helps them continue their growth without a hitch. For those planting directly outside, patience is key, but the reward of seeing those first green shoots is always worth the wait. You can find more information on planting times and variety differences in sunflower seed growth.

Seedling Stage: First Leaves and Early Growth (10–20 Days)

Once your sunflower seeds have successfully germinated and pushed through the soil, they enter the seedling stage. This is a pretty exciting time because you can really start to see your plants taking shape. For the first 10 to 20 days after sprouting, you’ll notice the initial growth of the seedling.

The most significant development during this period is the emergence of the first true leaves. Initially, a sunflower seedling will have two small, rounded leaves called cotyledons. These are essentially the seed’s stored food reserves. Soon after, the first set of true leaves will appear. These leaves are typically more elongated and will resemble the shape of the mature sunflower leaves, though much smaller. This is when the plant starts to photosynthesize and fuel its growth.

Here’s a quick look at what to expect:

• Cotyledons: The first two leaves that appear, often rounded.
• True Leaves: The subsequent leaves that emerge will look more like the adult plant’s foliage.
• Stem Elongation: The main stem will begin to grow taller, pushing the leaves upwards.
• Root Development: While not visible, the roots are actively growing downwards, anchoring the plant and seeking out water and nutrients.

If you started your seeds indoors, this is also the stage where you might consider transplanting them outdoors, provided the danger of frost has passed. It’s important not to leave indoor seedlings in their starter pots for too long, as their roots can become pot-bound. I found that my seedlings were ready to move outside after about two weeks, and they seemed to handle the transition well. It’s a good idea to harden them off first, though, to get them used to the outdoor conditions. This process helps prevent transplant shock and ensures they continue growing strong.

During this early phase, the seedling is quite delicate. It’s important to provide consistent moisture without waterlogging the soil. Too much or too little water can really set back their progress. I learned this the hard way with a batch last year; they just didn’t thrive.

Keep an eye on your seedlings during these first few weeks. They are building the foundation for the impressive growth that’s to come.

Vegetative Growth Phase: Rapid Stem & Leaf Development (Days 20–60)

After the initial sprout and the appearance of those first true leaves, my sunflowers hit their stride. This period, roughly from day 20 to day 60 after planting, is all about rapid growth. The plant focuses all its energy on getting bigger and stronger, building up that sturdy stem and developing a good canopy of leaves. It’s quite a sight to see them shoot up day by day.

Stem Thickening and Height Gain

During these weeks, the main stalk of the sunflower thickens considerably. I’ve noticed that the spacing I give them impacts this. Closer spacing means thinner stalks, which is fine if I’m aiming for lots of smaller blooms for bouquets, but for those big, showy heads, I give them more room. For branching types, this is also when they start developing side shoots if I decide to pinch them back, which can lead to multiple blooms later on.

Leaf Production and Photosynthesis

The leaves are the plant’s food factories, and during this phase, they ramp up production. You’ll see more and more leaves unfurling, each one working hard to capture sunlight. This is why good light exposure is so important. If my plants are too crowded, or if they’re shaded by other taller plants, I can see a difference in how robust they look. It’s a good time to think about feeding them, too. A balanced fertilizer can help fuel this fast growth, giving them the nutrients they need to build strong stems and lots of leaves. I usually apply a slow-release fertilizer once the second set of leaves appears.

Factors Influencing Vegetative Growth

Several things can affect how quickly my sunflowers grow during this stage:

• Sunlight: Plenty of direct sun is a must. They need at least 6-8 hours a day.
• Water: Consistent moisture is key, especially as they get bigger and need more water.
• Soil Nutrients: Healthy soil with adequate nutrients supports vigorous growth.
• Temperature: Warm weather is ideal for sunflowers; they don’t like the cold.

I’ve found that paying attention to these basics makes a noticeable difference in how quickly my sunflowers develop during this critical vegetative phase. It’s not just about planting the seed; it’s about giving them what they need to thrive.

Comparison of Growth Speed (Approximate)

While exact numbers vary by variety, here’s a general idea of what I expect:

Growth Aspect	Approximate Timeframe (Days 20-60)	Notes
Height Increase	1-3 inches per day	Varies greatly by variety
New Leaves Appearing	Every 2-4 days	Depends on conditions
Stem Diameter Growth	Steady thickening	Influenced by spacing and nutrients

This stage is the engine room for sunflower growth. Getting it right means I’m setting myself up for a great bloom and seed harvest later on. It’s also a good time to check for any early signs of pests or diseases, though thankfully, sunflowers are pretty tough. If I ever run into issues with my garden, like a sudden lack of space for new plants, it reminds me of how a server can run out of storage.

Bud Formation & Reproductive Stage: Prepping for Bloom (Days 60–80)

Around this time, usually between 60 and 80 days after planting, I start to notice a significant change in my sunflowers. The rapid stem and leaf growth from the previous phase begins to slow down a bit, and the plant shifts its energy. This is when the magic starts to happen – the development of the flower bud. It’s a pretty exciting phase to watch, as the plant prepares to show off its bloom.

The Bud Appears

This is when the main flower bud starts to form at the top of the main stem, or the ends of side branches if you’re growing a branching variety. It starts small, almost like a little nub, and gradually gets bigger. For single-stem varieties, you’ll see one large bud forming. Branching types will develop smaller buds at the end of each side shoot.

Bud Development and Size

The bud will continue to grow and swell over these weeks. Its size will depend a lot on the sunflower variety you planted and the growing conditions. A healthy bud will feel firm and look plump. If you’re growing sunflowers for cut flowers, this is a key stage to pay attention to. Some growers even ‘pinch’ the central bud on younger plants (when they’re about 8-12 inches tall) to encourage more branching and multiple blooms, but this is only for specific types and must be done early on.

Energy Shift in the Plant

During this reproductive stage, the plant is channeling a lot of its resources into developing that bud. You might notice that the leaves are still growing, but the stem might not be getting as tall as quickly as it was before. It’s all about getting that flower ready to open.

It’s important to remember that this stage is all about preparation. The plant is working hard behind the scenes to create the beautiful bloom we’re all waiting for. Patience is key here, as the bud needs time to develop properly before it can open.

Blooming Phase: When Do Sunflowers Flower Fully? (Around Day 70–90)

The Grand Unveiling: When Blooms Appear

Around 70 to 90 days after planting, my sunflowers typically start to show their full glory. This is the blooming phase, where those tightly furled buds finally open up, revealing their sunny faces to the world. It’s quite a sight, especially when you’ve been watching them grow from tiny seeds. The exact timing can shift a bit depending on the specific variety I’ve chosen and the weather we’ve had. Some types might be a little earlier, others a bit later, but this window is generally when the magic happens.

Harvesting for Cut Flowers: Timing is Everything

If I’m growing sunflowers specifically for bouquets, I’ve learned that timing the harvest is key. For the longest vase life, I need to cut them just as the petals are starting to lift off the face of the bloom, before they’re fully open. It feels a bit early, but this way, they’ll continue to open up over the next day or two in the vase. If I wait too long and the petals start to point backward, they won’t last nearly as long. It’s a delicate balance, and sometimes the weather can rush things along, like a sudden rain followed by sun, making them all open up faster than I can harvest them.

What to Expect During the Bloom

Once they’re in full bloom, sunflowers become a magnet for pollinators. Bees and other helpful insects visit them frequently, which is great for the garden ecosystem. This is also when the plant is focused on producing seeds. Generally, a sunflower bloom will last for about two to four weeks. However, I’ve noticed that the branching varieties tend to keep blooming for a longer period, offering color throughout the summer and into fall.

It’s important to remember that if I’m growing sunflowers for seeds, I need to let the flowers stay on the plant until they mature. Harvesting them for cut flowers means I miss out on seed production for that particular bloom.

Post-Bloom Care and Seed Development

After the main blooming period, the flower heads will start to droop and turn brown. This is a sign that the seeds are developing and maturing. I usually let them dry on the stalk, but if I’m worried about birds or squirrels getting to them first, I might cut the heads off and hang them indoors to finish drying. It’s a bit of a race against wildlife sometimes, but it’s worth it for the harvest. If you’re having trouble with your plants not growing as expected, it might be due to a storage issue, like insufficient space for the plant’s needs.

Peak Flower Period: How Long Do Sunflowers Stay in Bloom?

How Long Do Sunflowers Stay in Bloom?

Once my sunflowers finally open up, I always wonder how long I can enjoy their cheerful faces. Generally, a sunflower bloom will last for about two to four weeks. It’s a pretty decent stretch, giving me plenty of time to admire them, take photos, and maybe even cut a few for a vase.

However, this timeframe can change depending on the type of sunflower I’m growing. Some varieties are bred for a longer show, while others are more fleeting. For instance, branching sunflowers are quite different from the single-stem giants. While a single-stem sunflower puts all its energy into one big head, branching types produce multiple smaller blooms over a longer period. This means that while one bloom might fade, new ones keep popping up on the same plant.

It’s also interesting to note that the conditions in my garden play a role. Good soil, enough water, and plenty of sun help the plant stay healthy and keep those blooms looking good for longer. If I’m growing them for cut flowers, I try to harvest them when a few petals are just starting to lift. This seems to give them the best vase life. If I’m leaving them for the birds or seed production, I let them go until they naturally start to dry out and droop.

The peak bloom period is a beautiful, but temporary, phase in the sunflower’s life. It’s a time when the plant is at its most visually striking, attracting pollinators and bringing vibrant color to the garden. Understanding how long this phase lasts helps in planning for harvests, whether for cut flowers or seeds, and appreciating the full cycle of this amazing plant.

Here’s a general idea of what to expect:

• Single-stem varieties: Typically bloom for 2-4 weeks.
• Branching varieties: Can bloom for a much longer period, often from mid-summer until the first frost, as new flowers open sequentially.
• Environmental factors: Heat, water, and nutrient availability can influence bloom duration.

It’s always a good idea to check the specific variety’s information, as they can differ quite a bit. I found that knowing the expected bloom time helps me plan my garden activities, like when to expect pollinators or when to start thinking about seed harvesting. It’s all part of the fun of watching them grow, and I’ve learned a lot about sunflower growth just by observing them season after season.

Seed Development: From Flower to Edible Sunflower Seeds

Once the vibrant petals start to fade and the sunflower head begins to droop, that’s my cue that the seeds are developing. This phase is all about the seeds maturing inside that big, impressive flower head. It usually takes about a month after the blooms have opened for the seeds to reach readiness. You’ll notice the back of the flower head turning from green to a yellowish-brown color, and the seeds themselves will start to plump up, and their shells will harden.

Here’s a general timeline I follow:

• Flower Blooms: Around day 70-90.
• Seed Development Begins: Starts shortly after blooming.
• Seeds Mature: Approximately 30 days after blooming.
• Harvest Ready: Around day 100-120, depending on the variety.

The key indicator for me is when the back of the flower head starts to turn brown and the seeds feel firm to the touch. If I’m worried about birds or squirrels getting to them first, I’ll often cover the developing heads with a mesh bag or cheesecloth. This lets air circulate but keeps the critters out. It’s a simple trick that helps protect the fruits of my labor. I’ve learned that patience is key during this stage; letting the seeds dry on the stalk as much as possible helps them develop their best flavor and texture. For more on the sunflower life cycle, this part is quite important.

When the time is right, I’ll snip the flower heads off, leaving a bit of stem. Then, I’ll hang them upside down in a dry, airy place to finish drying completely. This ensures the seeds are fully mature and ready for harvesting, whether for snacking or saving for next year’s garden.

Maturity & Harvest Timing: When Are Sunflower Seeds Ready?

So, you’ve watched your sunflowers grow tall and strong, and now you’re wondering when those tasty seeds will be ready to harvest. It’s a pretty straightforward process. Generally, you’re looking at about a month after the flowers have fully opened. Keep an eye on the back of the flower head; when it starts to turn from green to a yellowish-brown, that’s your first big clue. The head will also begin to droop or nod downwards. At this point, the seeds themselves should look plump with formed shells.

Signs of Maturity

• The back of the flower head changes color: It shifts from green to yellow-brown.
• The flower head droops: It starts to nod downwards.
• Petals dry and fall off: The tiny petals covering the seeds dry out and drop, exposing the seeds.
• Seeds have hard shells: They look fully developed and aren’t soft or milky.

Harvesting for Seeds

When you see these signs, it’s time to think about harvesting. You have a couple of options. You can let the flower heads dry completely on the stalk. This is the most natural way, but you’ll need to watch out for birds and squirrels who also have a taste for sunflower seeds. If you want to beat them to it, you can cut the flower heads off with about a foot of stem attached. Then, bundle them loosely and hang them upside down in a warm, dry, well-ventilated spot indoors. This protects them from pests and moisture, which can cause mold. I usually let mine cure for a few weeks after bringing them inside.

Preparing Seeds for Storage

Once the seeds are thoroughly dry, you can remove them from the head. Rubbing two heads together works well, or you can use your fingers or a stiff brush. After you get them off, let them dry for a few more days, perhaps in glass jars, before storing them. This helps keep them fresh. It’s important to keep them in a place without too much humidity, like the refrigerator, to maintain their flavor. It’s a bit of a process, but getting those homegrown seeds is worth it. If you’re interested in different types of sunflowers, some varieties mature much faster than others, with some ready in as little as 55 days, while giants might take up to 120 days. This means your harvest timing can vary quite a bit depending on what you planted. I found that understanding the days to maturity on the seed packet is helpful, but always double-check the physical signs on the plant itself.

Variety Matters: Fast-Growing Sunflower Types (55–120 Days)

It’s pretty amazing how many different kinds of sunflowers there are, and they really do grow at different speeds. When I first started gardening, I just grabbed whatever looked pretty, but now I know better. Some sunflowers are super speedy, going from seed to bloom in as little as 55 days. Others, especially those giant ones, can take up to 120 days. It makes a difference if you’re trying to get a quick splash of color or if you’re planning for a longer harvest.

Fast-Growing Varieties

If you’re looking for sunflowers that mature quickly, you’ll want to check out varieties like ‘ProCut Red’ or ‘Ruby Eclipse’. These are often ready to show off their blooms in about 55 days. They’re great if you want that sunflower look without a long wait. I’ve found that planting these types in succession, every couple of weeks, gives me a continuous display all summer long. It’s a good way to keep the garden looking cheerful.

Mid-Season Bloomers

Then there are the sunflowers that fall somewhere in the middle. Many popular ornamental types, often grown for cut flowers, will be ready in about 70 to 100 days. These are the ones that give you a good balance of speed and a substantial bloom. For example, the ‘Sunrich Orange’ is a classic choice that usually matures in 60-70 days, offering that traditional sunflower look.

Slow-Growing Giants

On the other end of the spectrum, you have the giants. Varieties like ‘Mammoth Grey Stripe’ are impressive, but they take their sweet time. I’ve seen them take as long as 120 days to fully mature. These are the ones you plant early in the season if you want a really big show later on. They’re worth the wait if you’re aiming for those massive flower heads.

Single Stem vs. Branching

It’s also worth noting the difference between single-stem and branching types. Single-stem sunflowers produce one large flower per plant and are often the fastest to mature. Branching types, on the other hand, produce multiple smaller flowers over a longer period. While they might take a bit longer to get going with all their blooms, they offer a more extended flowering season. This variety in growth habits means you can pick sunflowers that fit your specific gardening goals, whether it’s speed or duration of bloom. It’s all about choosing the right sunflower seeds for your garden.

Tips to Speed Up Growth

Want to give your sunflowers a little boost to grow faster? I’ve found a few things that seem to help. It’s not magic, just a bit of attention to what they need.

Soil Preparation

Sunflowers aren’t too picky about soil, but they do appreciate a good start. If your soil is heavy clay or very sandy, amending it with some compost before planting can make a big difference. This helps with drainage and gives them a nutrient kick right from the beginning. I usually aim for soil that’s well-draining but can hold a bit of moisture. It’s like giving them a comfortable home base.

Watering Wisely

When they’re just starting, sunflowers need consistent moisture. I try to water them lightly every day for the first week or so after planting, especially if it’s dry. Once they’ve got a few sets of leaves and are a bit more established, you can ease up a bit. They can handle some dry spells, but for really fast growth, keeping the soil consistently moist, but not waterlogged, is key. Watering them when you fertilize also helps the nutrients get to the roots.

Feeding Your Sunflowers

Once my sunflowers get their second set of leaves, I like to give them a little food. A balanced, slow-release fertilizer works well. Some folks suggest a split application – putting some down when planting and then again later in the season. This can help keep them fueled for steady growth. Just remember to water them after fertilizing so the food can get into the soil where the roots can reach it.

Succession Planting for Continuous Growth

If you want a steady supply of sunflowers or just want to see them grow throughout the season, succession planting is the way to go. This means planting new seeds every few weeks. You can plant the same variety, or mix it up with different types that have varying maturity dates. It’s a simple way to extend the blooming period and keep the garden looking lively.

Starting Seeds Indoors

For an even earlier start, I sometimes begin seeds indoors. Using biodegradable pots is handy because you can plant the whole pot later, disturbing the roots as little as possible. Just be sure to ‘harden off’ the seedlings before moving them outside. This means gradually getting them used to the outdoor conditions over a week. It prevents shock and helps them transition smoothly. Soaking seeds before planting can also speed up germination, giving them a head start before planting.

Getting the timing right with planting, watering, and feeding can make your sunflowers shoot up. It’s all about giving them what they need, when they need it, and not being afraid to give them a little extra help along the way.

Want to make your plants grow faster? We’ve got some great tips on how to improve your soil, manage watering, use the right fertilizer, and plan for succession planting. Want to learn more about boosting your garden’s growth? Visit our website for all the details!

Frequently Asked Questions

When is the best time for me to plant sunflower seeds for fast growth?

I typically wait until after the last frost, usually around mid-May here in Michigan, to plant my sunflower seeds directly into the ground. If the soil feels warm, it’s a good sign the seeds will sprout quickly.

How long does it typically take for sunflower seeds to sprout after I plant them?

Sunflower seeds usually start to show sprouts within 7 to 10 days after planting. It’s quite amazing how fast they break through the soil!

What happens right after my sunflower seeds sprout, and how long does that part take?

After the seeds sprout, the young plants, or seedlings, will develop their first leaves. This early growth phase usually takes about 10 to 20 days.

During what period do sunflowers grow the fastest in terms of stem and leaf development?

The most rapid growth, where the stem gets taller and more leaves appear, happens between day 20 and day 60 after planting. This is when they start to look like sunflowers!

When can I expect to see flower buds forming on my sunflowers?

Sunflower buds start to form around 60 to 80 days after planting. This is the stage right before they open up into those beautiful flowers we love.

About how many days does it take for sunflowers to fully bloom after planting?

Most sunflowers will be in full bloom, meaning their petals are fully open, around 70 to 90 days after you plant the seeds. Some varieties might take a little longer.

After the flowers open, how long do I need to wait until the sunflower seeds are ready to harvest?

Once the flowers open, it usually takes about a month for the seeds to mature. You’ll know they’re ready when the back of the flower head turns brown and starts to droop.

Are there specific sunflower varieties that grow faster than others?

Some sunflower types grow much faster than others. For instance, varieties like ‘ProCut Red’ can be ready in as little as 55 days, while giant types might need up to 120 days to mature.