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Vegetable Seeds: Which to Sow Outdoors vs. Indoors?

You have your seed packets, you have your seed starting essentials, and you have a garden plan – sounds like you are ready to plant and grow a garden!

But are you sure you know which seeds can go directly into your garden soil, and which will do better if you start them indoors?

When preparing to plant your veggie seeds, there are some general guidelines to follow – since some do better being sown directly into your garden while others need the more protected conditions that sowing indoors provides.

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In this article you’ll learn not only which veggies should usually be planted indoors and which outdoors, but why, so that you can make a well-informed decision for any variety you decide to grow in the future.

And I’ll also mention some exceptions that may work well for your own garden.

Here’s an overview of what I’ll cover:

What You’ll Learn

Count Your Growing Days

Before we get started, it will be very useful for you to have an idea of the length of your growing season – that is, how many frost-free days you have on average between your last frost in spring and your first frost in fall.

In my Zone 5 garden, if I didn’t acknowledge and respect the length of my – rather short – growing season and plant my seeds accordingly, my harvests would be paltry, and I would be faced with disappointment, year after year.

I’d probably conclude that I didn’t have a green thumb and gardening just wasn’t for me!

Instead, I must humbly accept that my growing season is only about 130 days long, on average – lasting roughly from the beginning of June through the end of September.

I adapt my planting strategy to this number rather than crossing my fingers and hoping that, maybe, my first frost will come late this year.

And you should know the length of your growing season, too.

If you aren’t familiar with the length of your growing season, this tool from the National Gardener’s Association can help you calculate this number.

Here’s how it works:

Just type in your zip code, wait for the next page to appear showing a chart of probabilities for average first and last frost dates, then scroll down and click the “Garden Planting Calendar” link for your location.

Then you’ll see the average number of days in your local growing season.

So, once you have calculated your number of frost-free days, we’re ready to dig in to the particulars of our vegetable seed needs.

Direct Sow Outdoors

Even working with a measly 130 frost-free days, I generally like to direct sow as many of my crops as possible – and I encourage you to do so, too.

There is less work involved in this approach – no hardening off or transplanting, and no worrying about young seedlings being shocked by the change from indoor to outdoor living. We don’t use the term “hothouse flower” to describe delicate individuals for nothing!

Luckily, there are many, many more types of edible annuals that can be directly sown compared to the number that must be started as transplants, so it is pretty easy to plant the bulk of your vegetable garden directly from seed – especially if you choose to grow a wide variety of veggies.

With the goal of direct sowing as many crops as possible in mind, let’s start by considering what we can easily start outdoors, right in the garden.

Cool Season Crops

Outdoor temperatures in spring tend to be on the cool side, which is just what we need for sowing most cool season crop seeds. These seeds are generally planted several weeks before the last frost date.

Cool season crops are well adapted to chilly conditions and tend to grow best in spring and fall. And many, such as arugula seeds, actually germinate better in cold soil.

Arugula seedlings, reaching for the light.

Cool weather crops that you should plan on direct sowing include:

While many cool season crops are fairly cold hardy, different plants have different levels of susceptibility to frost.

For an in-depth look at which plants are frost hardy and to what degree, check out our article on frost damage in vegetables.

And if you have hard freezes late in spring like I do, make sure to keep an eye on your weather report, and plant after any risk of dips back into the low temperatures.

Fava beans, ready for sowing.

There are some exceptions to the cool season rule.

Some cool season plants will bolt when exposed to light frosts, or days with temperatures below 50°F – bok choy and tatsoi, for instance.

These cool weather crops can be direct sown – or started indoors and transplanted out – after the first frost date for better results.

Short Season Tender Annuals

Other vegetables that do well with direct sowing are tender annuals that can fully mature during a short summer season – within 110 days or less.

These plants are not cold hardy, so they should be sown after all risk of frost has passed – and they will generally have plenty of time to reach maturity when direct sown.

Short season tender annuals include most varieties of:

However, some varieties of cucumbers, melons, and squash are slower to mature. I’ll address those in just a bit.

Seedlings that Don’t Transplant Well

There are some veggies – both cool season and warm season crops – that should be direct sown because their seedlings aren’t typically very successful when transplanted.

Some have sensitive root systems, which are easily disturbed during transplanting – such as carrots and spinach, two cool season plants.

Others, like radicchio, tend to bolt when transplanted, so direct sowing remains the best planting method.

Here’s a list of veggies that are poor candidates for transplanting, and should always be direct sown:

  • Beans (pole, bush)
  • Carrots
  • Radicchio

And then there is another group of veggies that only do moderately well with transplanting, so direct sowing is recommended if possible:

If transplanting is the preferred method for growing these veggies in your garden nonetheless – for reasons I’ll get to below – you’ll have greater success if you use biodegradable pots for starting your seeds.

However, transplanting in biodegradable pots will only work if you live in a climate where the biodegradable pot will actually break down.

For those of us who are gardening in dry climates, the biodegradable pot won’t stay wet enough to break down properly, and this could eventually stunt the roots of the transplant.

An alternative that works even in dry climates is to grow these delicate-rooted veggies in compressed soil blocks.

According to Master Gardener Sandy Patry, in a 1993 edition of “Cognition: The Voice of Canadian Organic Growers,” published by McGill University’s Ecological Agriculture Projects, these blocks increase survival rates of seedlings dramatically by reducing damage to seedling roots during transplanting.

You can make your own blocks of compressed soil with the Ladbrooke soil blocker, available via Amazon.

Start Indoors

Unlike the freewheelers mentioned above that grow productively when their seed is conveniently placed directly in your garden soil, some types of vegetables perform reliably better when started indoors.

And beyond the preferences of your seeds as to how they get their start, there are times when you may want to give your preferences priority, and start some of the above indoors anyway.

Long Season Tender Annuals

Generally, the vegetables that are sown indoors are the ones that are tender (frost sensitive), require warmer germination conditions, and need additional time to reach maturity – long season tender annuals.

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These seeds are started indoors, either in a warm and sunny southern facing window, under grow lights, or in a heated greenhouse, usually 6-10 weeks before the first frost. Then they are transplanted out to the garden after all risk of frost has passed.

Depending on the variety, different plants can require varying amounts of time to grow from seed to maturity. Some tomatoes can take 140 days to reach maturity, and some pepper varieties need 175 days.

Plus, many plants will produce harvestable crops over an extended period – so we don’t want to choose cultivars that won’t reach maturity until the day before our first frost. We want to give them additional time to keep producing.

In most places in the US, the growing season isn’t quite long enough to successfully bring these tender plants to maturity and allow them ample time for fruit production when sown directly into the ground.

So these plants, all of which happen to be nightshades, are best started indoors and then transplanted into the garden:

Although starting indoors is the general recommendation for these veggies, you may want to experiment with direct sowing – particularly if you have a long growing season.

Eggplant seedlings growing in a sunny windowsill.

Have you ever had volunteer tomatoes come up in your garden soil, and even produce fruit?

Yep, me too – even in Zone 5. (However, these successful volunteers tend to be from short season varieties.)

If you want to experiment with sowing your nightshade seeds directly in your garden, just compare the days to maturity listed on your seed packet to the number of days in your local growing season, and make sure there is some extra time available for the plant to bear fruit before the first frosts arrive.

As a general rule, start these vegetable plants indoors for a higher probabilities of success – and early harvests.

And don’t forget about germination temperature requirements. Tomatoes require soil temperatures to be 70-90°F to germinate, so when experimenting, wait until your soil is nice and warm. For indoor seed starting, a heat mat can come in handy.

If you’re growing tomatoes from seed, you’ll find some great tips in our tomato seed starting guide.

Long Season Varieties

In addition to the tender annuals mentioned above, there is another group of veggies that often need to be started indoors.

These are the slower-growing varieties of various types of vegetables that are commonly short season plants. This group includes certain cultivars of:

Slow-growing varieties of these plants may not have enough time to come to maturity if sown outdoors in many USDA Hardiness Zones.

Always check the days to maturity for your seeds and compare this against the number of days in your local growing season.

If the days to maturity are beyond or very close to the number of days in your frost free season, start these varieties indoors to give them a head start.

When I checked the average number of days in my local growing season, I realized that if I want to successfully grow loofah gourds in my garden, which can take 200 days to mature, I’d better start them indoors about 10 weeks before I plan to transplant them.

Slow-Growing Cool Season Crops

There are also certain vegetables that almost never have time to reach maturity when started outdoors, and which will need to get a good head start on the normal growing season.

These crops are adapted to regions with cooler climates, which can make them difficult to grow in places with hot summers.

Starting them indoors well before the last frost date will allow them to enough time to become established and develop some resiliency before the heat of summer sets in.

An artichoke seedling.

Brussels sprouts are one crop that is usually started indoors in most regions because it is such a slow grower.

Brussels sprout seedlings.

Since some varieties of brussels sprouts can take up to 200 days from transplanting to reach maturity, starting these plants indoors is a requirement in most zones.

For Short Growing Seasons

As I mentioned earlier, some of us have to make do with a limited growing season, and even common “short season” tender annual crops may not grow to maturity within our average number of frost-free days.

For us short-season gardeners, we’ll want to compare our local number of frost-free days against the total average number of days to maturity on seed packets for all or most of our tender annuals – just to make sure we’ll have enough time to pick a tasty harvest.

And if any of our intended crops won’t have time to reach maturity, we should consider starting them indoors. Be on the lookout for cultivars of certain types of produce known for shorter numbers of days to maturity as well.

Tender annual crops that commonly need to be started indoors by gardeners with shorter growing seasons include:

  • Gourds
  • Watermelons and other types of melon
  • Winter squash

For Earlier Harvests

Even if your selected variety of a certain type of plant has time to reach maturity within your local growing season, you may want to some earlier harvests.

Starting seeds indoors is one way to get those early veggie crops.

You can start most any veggie indoors – except those that really don’t like transplanting – for an earlier harvest.

My father-in-law plants his garden this way every year. He buys summer squash transplants, but when he plants them in his garden, he also plants additional seeds.

This way he gets a few early squash from his transplants, and then his seed-sown plants take over and out-produce the transplants. It’s a beneficial tactic to fill the hunger gap.

Beyond hopes for early squash, you may also want to use transplants to produce earlier harvests if your spring weather tends to heat up quickly.

Stifling, hot weather will slow the growth of many crops. In warmer climates, starting plants in the winter and setting seedlings out early can help you to beat the worst of the heat.

Plants That Prefer Transplanting

Just as some plants prefer being sown directly into the garden, there are also certain crops that profit from transplanting, such as broccoli, cauliflower, and Romanesco.

These crops are finicky about their growing conditions, and tend to be more productive when transplanted out to the garden as seedlings.

Quick Reference Guide

Cool Season Crops Warm Season Crops
Sow Outdoors Before Last Frost Sow Outdoors After Last Frost
Arugula, batavia, beets, Belgian endive, broccoli raab*, bunching onions*, carrots, collards*, corn salad, daikon, fava beans, fennel (bulb)*, frisee*, kale*, kohlrabi, leeks*, lettuce*, mizuna, mustard, orach, parsnips, peas, radicchio, radishes, rutabagas, shallots*, spinach*, Swiss chard*, turnips, watercress Amaranth, beans (bush, pole), bitter melon*, corn, cucumbers*, edamame, gourds*, loofah*, melons*, okra, pumpkins*, summer squash*, watermelons*, winter squash*
Start Indoors Start Indoors
Artichoke, bok choy (pak choi)**, broccoli**, brussels sprouts**, cabbage,** cauliflower, celeriac, celery**, Chinese cabbage**, onions (bulb)**, romanesco, tatsoi** Eggplant, ground cherries**, hot peppers, malabar spinach**, New Zealand spinach**, sweet peppers, tomatoes, tomatillos

* can be started indoors if preferred, or if season is short

** can be direct sown outdoors in some cases

Sow Much Produce

Now that you have some general guidelines to determine which veggies to sow directly in the garden and which should be started indoors, you should be ready to divvy up your seed packets into two separate piles.

But before you get busy with your indoor seed sowing, why not brush up on your skills with our guide to starting annual seeds indoors?

If you calculated the length of your local growing season, did you discover any surprises about seeds you should really be starting indoors? Let me know in the comments.

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And if you’re getting ready to start a vegetable garden, these articles will come in handy:

© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Product photo via Ladbrooke. Uncredited photos: Shutterstock. With additional writing and editing by Allison Sidhu.

Weed seasons: understanding the best time to grow cannabis in America

Are you thinking about growing your own cannabis? New to being a plant parent? Wondering when you should plant your cannabis seedlings outdoors?

Let’s talk about what “weed season” means in the US, and how you can time your outdoor grow to get the best results.

Photo by: Damien Robertson/Weedmaps

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What is weed season?

Weed season is an affectionate term for the eagerly awaited outdoor cannabis growing season, a period that touches our spring, summer and fall seasons.

In the Northern Hemisphere weed growing season can kick off as early as April, when gardeners and farmers might start seedlings indoors. Cannabis plants typically flower in late summer through fall, and the season can run as late as mid-November in warmer climates where some cultivars take a long and luxurious time maturing their buds.

Why do growers plant and harvest cannabis at specific times of the year?

Like any farmer or gardener, cannabis farmers and gardeners typically get their plants in the ground as soon as the weather is warm enough and the days are long enough.

This, of course, varies by region. Farmers in California enjoy generally warmer growing seasons and can plant outside earlier while also harvesting later than, say, New York, whose growing season is shorter on both ends. Regardless of where you’re growing, the main goal is to time planting for maximum light during the summer and maximum growth before fall sets in.

For photoperiod plants, timing is everything. Photoperiod cannabis plants take their cue from Mother Nature (or more specifically the number of uninterrupted hours of darkness) to start flowering. As fall sets in and hours of darkness hit twelve per night, the plant will be triggered into its flowering stage.

There are also cannabis plants that aren’t light-sensitive, called autoflower varieties, that will automatically flower on their own at a particular point of their maturity independent of how much light they’re getting. These plants tend to have much shorter life cycles, which is appealing to some gardeners.

Harvesting happens when the plant’s flowers have fattened up but before the very cold weather comes on, typically by mid to late fall.

Phases of growth and timing for outdoor growers

Speaking of life cycles, let’s talk about the plant’s stages of growth and development. This is where we see the importance of timing once more, since outdoor cannabis growers try to map out the growing season and find the sweet spot for optimal plant development.

Early spring: germination stage Photo by: Gina Coleman/Weedmaps

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Early spring: germination stage

If you’re growing from seed, the first step in the life of your cannabis plant is germination. Once the seed has sprouted, it will immediately grow two little round leaves, called cotyledon leaves, that will be responsible for delivering energy to the seedling until it starts to grow the more familiar fan leaves we all know and love.

As far as timing when to sprout your seeds, a general rule of thumb is on or around the Spring Equinox. If you’re not growing from seed but instead buying clones, they’ll already be in the seedling stage when you get them so you don’t have to worry about germination.

Spring to early summer: seedling stage Photo by: Gina Coleman/Weedmaps

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Spring to early summer: seedling stage

Seedlings are baby plants. Whether you’ve sprouted your own seed or bought a clone, during this first stage of life the plants are delicate and sensitive.

Folks in cooler climates often elect to start plants indoors to keep them safe and warm, waiting to plant outdoors until they’re somewhere between 6 inches and a foot tall and strong enough to handle the environment outside. Even in warm climates, many growers like to start their plants indoors to give them a leg up since seedlings are susceptible to pests, disease, and mold.

In cooler climates, growers should wait on putting plants in the ground until there is no danger of overnight frost, and plenty of sunshine. As Bill Cook, master grower at Kanna-Wise eloquently put it, “a heavy freeze is killin’ your trees.” An old gardener’s rule of thumb is to move plants outside after Mother’s Day, and they should definitely be outside and/or in the ground by the Summer Solstice.

Of course, you could always grow your plants in pots or containers. Lots of outdoor growers elect to use pots and other containers, and they offer the added benefit of being able to bring the plants out during the day and inside if nights tend to be cold.

Summer to early fall: vegetative stage Photo by: Gina Coleman/Weedmaps

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Summer to early fall: vegetative stage

The vegetative stage is when the plant’s growth will really take off. For several weeks, it will grow more foliage, reaching ever upwards to that glorious summer sun.

During this phase, growers might consider topping and training their plants to encourage outward growth. This provides more even distribution of light to the leaves while also managing overall plant height. More water will be needed as the plant develops large root systems and additional nutrients like nitrogen are beneficial as the plant matures.

If you aren’t working with exclusively female plants, you’ll need to get rid of the males before they have a chance to pollinate the females (and wreck your harvest). “Even feminized seeds can have up to 10% males in the mix so it’s important to inspect your plants every day as they start to show their sex. Also important to note is that a stressed female plant can produce male branches or ‘hermaphrodites’, so even if you know she’s a girl, you have to check daily,” advised Sara Rotman, a veteran grower and founder of Wellfounded Botanicals.

A photoperiod plant will continue to live its best vegetative life until the light-to-dark ratio starts to tip in favor of darkness. When photoperiod plants start getting 12 hours of darkness, they will move into their final phase — and perhaps the most exciting for growers — the flowering stage.

Fall: flowering stage Photo by: Gina Coleman/Weedmaps

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Fall: flowering stage

For the final stage of a female cannabis plant’s life, most of its energy will be put into producing flowers. The flowering stage happens in three phases:

  • Flower initiation: You’ll start to see white, hairy pistils developing, hinting at the buds to come. The plant will continue to grow, but growth will start to slow down.
  • Mid-flowering: You will start to see the buds take shape, and the plant will stop growing.
  • Late-flowering/ripening: The flowers will really fatten up, becoming sticky and very covered in trichomes. When the pistils turn from white to brown, you can start to think about a harvest.

As the flowers fatten up, they might become too heavy for the branches to handle, and growers often give their plants some help with a trellis, bamboo canes, or another form of support. Extra nutrients like phosphorus are often given during the flowering stage.

Mid-to-late fall: harvest season Photo by: Gina Coleman/Weedmaps

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Mid-to-late fall: harvest season

Timing the harvest is an art form in and of itself, though the general rule of thumb is on or around the Fall Equinox. Aside from brown pistils, a close inspection of the trichomes is helpful. Generally, growers look for trichomes that have an amber hue to them. When the plant is ready to harvest you’ll probably also see the fan leaves starting to yellow, curl, and dry out.

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Tips for your outdoor grow

Use a grow journal. Tracking the details of your grow efforts, from germination to final cure, will help you become a better cannabis-plant parent. When it’s time for a new season, reviewing the successes and failures from the last crop will make your thumb greener — not to mention improve the quality and quantity of your final harvest. There are lots of ready-made cannabis grow journals out there, but really all you need is a pad of paper and an eye for detail.

Choose a strain for your region or microclimate. Some strains do better in some climates than others, and strain genetics will have a big impact on the growing season. In the northern half of the US where the season is cooler and shorter, growers might want to grow indica-dominant strains, whereas sativas will do well in the more hot and humid southern states that have longer growing seasons. Type of soil, volume of rain, and abundance of sun versus shade are other microclimate variables in your microclimate to consider when choosing a strain.

Plant companions. “Plant beneficial companion plants like marigolds, basil, lemon balm, or lavender. Not only do they invite pollinator insects into your garden, but they also invite beneficial insects like ladybugs and lacewings, which will prey on cannabis pests like aphids,” recommended Natalie Cox, a horticulturist and cannabis educator in Canada.

Keep learning. There is a lot to learn from your budding relationship with cannabis. There are also generations of growers who have shared their experiences, both online and in books. When it comes to cannabis, knowledge plus experience equals wisdom. We have a whole library dedicated to the plant for you to peruse. Luke Fletcher of Fletcher Farms Hemp Company added, “Talk to other growers and farmers in your region. You aren’t going to find all the answers on the internet. Good ‘ole fashion learning from others is a super valuable asset.”

What’s the Best Time to Start an Outdoor Cannabis Grow?

I t’s amazing how quickly the world can change, isn’t it? In the past 25 years, cannabis has moved from an illicit substance relegated to the shadowy corners of the illicit market to an “essential” industry amid COVID-19. In many states, local cannabis laws allow you to grow your own, and why not? When you grow your own, you can do your own quality control, know the purity of your product, and manage your own supply.

Luckily, you can start your own grow in a container as small as a flower pot. If you’ve got some space in your yard to grow weed outdoors, even better. So this may leave you wondering, when should I plant my cannabis outdoors? Luckily, there are some general date ranges to help guide your growing plans.

Regardless of which climate you’re starting in, when Spring Equinox comes around, start germinating your seeds. Make sure those plants get outside by Summer Solstice in June, then harvested around Fall Equinox.

For more specifics about how to protect your outdoor cannabis grows from the elements or whether you should grow indoors, outdoors, or in a greenhouse, check out the linked articles. Better yet, look into a book by celebrated cannabis growers like Ed Rosenthal’s Marijuana Grower’s Handbook, and of course, every green thumb’s favorite, The Farmer’s Almanac.

For a (shallow-ish) deeper dive into what to expect when growing cannabis outside, here’s a look at optimal grow times for regions across the U.S.

When to Grow Weed Outdoors by Region

Northwest (Northern CA, OR, WA)

When you grow outdoors in this loamy region you’ll never have to worry about getting enough rain. However, mold development and lack of sunshine can make growing outside a more difficult proposition.

Hybrids that flower earlier are suggested as the most successful grows, especially in Washington and Oregon. California plants can be put in the ground earlier due to the region’s warmer weather. Your best clue indicating that it’s time to start your outside grow is when daylight hours increase and the temperature starts to warm.

Related Articles

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  • The Flowering Stage Of Cannabis Week By Week

Midwest (IL, MI, Eastern CO)

This region is tricky because the weather is highly variable; rainy and muggy, and/or hot and dry. Winter may come early to this region, so choosing an indica-dominant hybrid strain might be your best bet, since their flowering times are shorter. Try to shoot for germination after the final frost of spring has passed in these regions.

Northeast (NY, MA, ME, VT)

With its rich soils and abundance of water, the northeast region can be a great place to grow cannabis outdoors, especially if you choose an early harvest strain that can finish up before fall kicks in. The best time to move your plants outside in this region is the middle of April, when days are longer.

Southwest (Southern CA, NV, AZ, NM, CO)

If you choose to grow outdoors in this scorching climate, be prepared to pay attention to the temperature, where highs that regularly exceed 100 degrees Fahrenheit will slow your plant’s growth. Sativas and sativa-dominant hybrids do well in this environment because of their lineage tracing back to the equator, where the weather is uniformly hot.

However, the dryness of the region means you’ll also have to carefully monitor your watering routines. Before moving your plants outside, make sure the last frost has passed. This last note is especially important in this region, as sudden, sporadic snowfall is common, so keep an eye on the weather.

Southeast (FL)

Though home cultivation is not yet allowed in the Sunshine State, many new medical producers getting into the industry are starting to grow outdoors, and there are a few things to be aware of if you’re licensed in the industry. The temperatures in Florida might be good for cannabis growing, but the humidity definitely is not.

In fact, because of all that moisture in the air, it’s best to avoid indica strains and grow sativas instead to avoid the mold that inevitably comes along with humidity. In this region, you could start the germination process as early as February. Just make sure that the last frost has passed before moving plants outside.


Of course, there are many different factors that go into the timing of an outdoor grow, and the weather will shift year-to-year. Use these estimates as rough guidelines and adjust as needed. Happy growing!

What’s the best time to plant outside in your area? Share in the comments!


Erin Hiatt is a New York City-based writer who has been covering the cannabis industry for more than six years. Her work – which has appeared in Hemp Connoisseur Magazine, PotGuide, Civilized, Vice, Freedom Leaf, MERRY JANE, Alternet, and CannaInvestor – covers a broad range of topics, including cannabis policy and law, CBD, hemp law and applications, science and technology, beauty, and psychedelics.

Erin’s work and industry insights have been featured on the podcasts The Let’s Go Eat Show, In the Know 420, and she has appeared as a featured panelist on the topic of hemp media. Erin has interviewed top industry experts such as Dr. Carl Hart, Ethan Nadelmann, Amanda Feilding, Mark A.R. Kleiman, Dr. James Fadiman, and culture icons Governor Jesse Ventura, and author Tom Robbins. You can follow her work on LinkedIn, WordPress, @erinhiatt on Twitter, and @erinisred on Instagram.