Raised Garden Beds – 24 Tips for Success
There are dozens of ways to start raised garden beds.
But successful gardeners do two things very well.
First, they build their garden in a way that sets them up for success.
Second, they follow certain steps through the season that dramatically increase their chance of success.
If you’re a beginner to raised garden beds, today we’re going to make it easy for you. All you need to do is carve out a few minutes of your day and tackle a couple of these techniques below.
1. Use a soil that increases the nutrient-density of your garden vegetables
Soil is by far the most important thing to get right to have a successful garden. Use a soil in your raised garden beds that has real topsoil in it. Real soil has dozens of critical micronutrients that plants need to be truly nutritious. Most soil that comes in bags feel fluffy and soft, but they don’t have micronutrients or enough calcium that plants need to be healthy. Real topsoil is heavier and might not drain as quickly because it has clay in it, but that’s good! Clay holds onto water and creates more consistent soil moisture for your plants. Read more about the Urban Farm Co’s soil for raised garden beds.
2. Use a frame for frost, hail, sun, and pest protection
This is one of the amazing tips that makes raised bed gardening great. Raised garden beds allow you to construct a frame that protects the garden from…anything.
- Buy 10’ long ½” gray electrical conduit instead of white PVC. It’s UV-resistant and will last much longer.
- Cut the fat end of the conduit off.
- Use ½” clamps to attach the conduit to the outside of one side of the raised garden beds.
- Hoop the conduit to the other side of the bed and attach it to the outside of the bed.
Once you have a frame built around the garden, you can place any material on it to protect your bed from [almost] anything nature has to offer!
- Hail & Intense Sun and Heat– We use an awesome fabric from FarmTek that shades 30% of the intense sunlight and also protects the bed from hailstorms. We use hand clamps to attach the fabric to the frame to keep it on tight.
- Cold – We use 6mm greenhouse plastic and construct a sturdy, thick, UV-resistant cover that creates a mini cold frame. It extends the growing season tremendously and allows gardeners to get their seeds in the ground earlier in the spring. Check it out in more detail here.
- Large Pests – We use a very tough mesh material to keep deer, dogs, cats, squirrels, raccoons, and rabbits out of the garden.
- Insects and Light Frosts – We use floating row cover (Reemay or Agribon) clamped to the frame. It’s incredibly versatile stuff.
3. Don’t get a raised bed wider than 4’
Raised garden beds allow you to avoid stepping on your soil. Stepping on the soil compacts the soil in a few inches in every direction around your foot (that’s not good). We don’t build our beds wider than 4’. Most people can reach in 2’ from either side of the garden bed. If you’re putting the bed up against a fence, only make it 2-3’ wide for the same reason.
4. Choose the right crops
For space efficiency, choose leafy salad greens. Kale, collards, and chard produce the most over the entire season. Spinach, lettuce, and arugula are great early in the season, but they bolt in the summer heat.
- For prolific production over the entire season, plant tomatoes and zucchini. Hot peppers produce well, as do cucumbers.
- Avoid things like Brussels sprouts, mint, sweet corn, and potatoes in raised garden beds.
For an awesome cheat sheet, check out The Urban Farm Company’s list of Most Suggested to Least Suggested Crops to Grow.
5. Mix the new soil with the existing soil
It might sound like overkill, but it’s a great idea to mix the soil in the raised garden beds with the existing soil in the ground. Plant roots really don’t like interfaces – two different soils sitting right on top of each other. Plant roots will actually bend sideways, or upwards, if they hit a hardpan soil they aren’t used to. Water does something similar. It will create a mini water table if it isn’t able to move through a consistent soil profile.
- If possible, till the existing ground just a bit.
- Add 2″ of soil to your raised garden beds.
- Mix the existing ground with the soil you added to the raised garden beds.
***If you have nasty weeds in the area like bindweed – just lay down landscape fabric and dump the soil on top. No worries about mixing.
6. Don’t plant your warm crops too early
Some people say plant on Mother’s Day. Some people say wait longer.
Putting your tomatoes in the garden before the last frost will surely end in dead plants.
But putting any warm crops in the ground when nighttime temperatures are still in the thirties or low forties will surely stunt the plants and decrease the final yield of your garden.
So we suggest planting your crops when nighttime temperatures are consistently in the mid- to high-40’s. This is usually no earlier than May 20th. Don’t worry about planting as late as June.
Here’s a rundown of when to plant your garden in Colorado.
7. Don’t use too much commercial compost
Compost is somewhat of a panacea for organic gardeners, but beware! Most compost you buy in bags or loose fill should be used conservatively. Every compost we’ve seen on the Front Range is high in salinity and potassium.
High salts cause plants to suffer. Beans are usually the first to die, but even if plants don’t die, high salts will stress them tremendously.
High potassium decreases nutrient density and causes “antagonisms” in the root zone, even though it will never kill a plant. There is usually plenty of potassium in Colorado topsoil, and commercial compost is like jet fuel when it comes to adding potassium.
We suggest adding 1/2″ of compost to your raised garden beds every year unless it’s homemade backyard compost. In that case, have at it and add as much as you can produce. Here’s a link to a great post about starting your own compost!
8. Build it close to the kitchen
It sounds stupid.
But this is critical.
The purpose of the garden is to produce food that you actually eat. Believe it or not, if the raised garden beds aren’t convenient then you won’t harvest the food.
The rule of thumb is it should be in a spot where you can walk out in your underwear in the morning to grab some veggies for your omelet or smoothie.
9. Keep the top of your soil wet for a week after planting
Seeds need warmth and moisture to germinate. Period.
The warmth part is easy if you plant from mid-April to August. But moisture is more difficult – especially with tiny seeds that are often only 1/8″ under the ground.
Water twice per day with a gentle shower setting to keep the top 1/2″ of your soil moist. You can tell the top of the soil is moist if it is dark in color. When it dries out, soak it again. If you do this 90% of your seeds will germinate no problem.
(If you’re a lazy gardener like us, and a week just sounds like too much, aim for three days. That should gets those seeds to pop.)
10. Focus on CONSISTENT soil moisture
Providing a garden with consistent water is one of the most difficult things in Colorado. It’s so hard. Sooooo hard!
(This makes sense because most of the crops we’re growing in our gardens didn’t actually evolve to grow in Colorado. You don’t see wild tomato plants or giant pumpkins while hiking in the woods, and most of the time the lack of moisture is the reason.)
More than half of all the raised garden beds we see with drip irrigation are actually over-watered.
So what’s the answer?
We’re working on that. Right now, we’re testing an automated watering system that is calibrated to optimal soil moisture. A device pulls water through the drip line when the soil dries out and shuts off when there’s proper moisture.
Until our new automated watering system becomes available (and even after), dig your hand in the soil and feel it. That is the BEST way to know if you need more or less water. It’s the BEST way to grow the two-pound tomatoes, the BEST way to grow a jungle of food, and the BEST way to have a healthy and beautiful garden.
Prioritize watering just a few minutes every day, feeling the soil to gauge if you should increase or decrease the time, and automating your watering system.
11. Plant space hogs outside of the garden
While space hogs like zucchini and winter squash will do great in raised garden beds, you should plant them outside of the beds!
Instead of taking up four squares for a single winter squash (that only produces a few squash), leave that space for high-value space-efficient crops like lettuce, basil, and herbs.
Squash are particularly prone to powdery mildew when they are spaced too close together, which often happens in raised garden beds. More reason to get them out if possible!
12. Use drip irrigation
There are dozens of ways to use drip irrigation. There are 1/2″ drip lines with drippers, 1/4″ drip lines with sprayers, t-tape, soaker hose, and a number of other options. We use a combination of 1/4″ drip line with emitters every 6″ and sprayers to ensure the entire surface of the soil get watered when the seeds are germinating.
Whatever drip line you decide to use, set it up on a timer of some kind. There are a few options…
Connected to An Existing Drip Line–
You can connect to an existing drip irrigation line in the landscaping. The disadvantage is that it will be on the same zone as perennial plants that may want to get watered twice a week for 30 minutes, when the raised garden beds may need to be watered every day for a couple minutes. Landscape plants won’t suffer, but it will be less versatile for your gardens needs. When we connect to an existing drip line, we also install a 20 PSI pressure reducer onto the line.
Drip Irrigation Connected to Your House’s Spigot—
When your drip is connected to your house, we put a Y-Valve, Timer, and 20 PSI Pressure Reducer onto your house spigot and connect the drip irrigation line to there. Your raised garden beds are watered directly from your house faucet. The timers are great because you can more easily control the time and settings and you don’t have to worry about your garden if you go out of town. Sometimes we encounter leaky or loud spigots that prevent us from connecting timers to the house until they are fixed.
Connecting to a sprinkler head in the area–
You can connect to an existing sprinkler system by connecting to the sprinkler head and adding a pressure reducer. We typically avoid this option unless it’s very straight-forward, and it is ok for the entire sprinkler zone to run every day for just a few minutes. Most bluegrass needs more water than that, so the gardener must be ok with prioritizing the water for the raised garden beds instead of the sprinkler zone.
13. Use trellises for climbing crops
Use a trellis to grow vertically! Pole beans and peas need a trellis. Cucumbers and tomatoes love them too.
Instead of taking 5 or 10 square feet to grow bush beans growing a few squares on a trellis is more interesting, fun, and space efficient.
Build a trellis by screwing 2×3″ or 2×4″ boards together in a rectangular frame. Line the outside with nails 6″ apart, and wrap a strong twine from nail to nail to create a trellis “netting”. Drill the wood frame onto the outside of the raised garden bed and you’re all set.
14. Weed early in the season
Weed seeds will naturally find their way into your raised garden beds. It’s just the way of the world. No worries!
If you can pull weeds early in the season, they won’t have time to produce seeds. When a weed plant “goes to seed”, it will often spread hundreds or thousands of seeds into your soil which will remain viable for years.
If you pull all weeds early and often in the beginning of the season, it’s a war of attrition.
And over time, you’ll win. The weeds will start to disappear slowly. No need for Round-Up in raised garden beds.
15. Thin your crops a few weeks after planting
Thinning is one of the most neglected garden tasks and one of the most important. Thinning is when you remove some plants from your garden to allow the others more room to grow.
When plants compete with one another for sunlight, nutrients, and space, their yields decrease significantly. For example, if all of your carrot seeds germinate but you don’t thin them, your carrots will be small and spindly. You will see a lot of green tops, but there won’t be much root when you pull them out.
How to Thin
The trick is to thin your crops to the recommended crops per square, shown in our Plants Per Square document. The most difficult part is killing a healthy young seedling. The best way to thin is to cut the plants at the soil level with a pair of scissors. Pulling them out may disturb the root systems of the neighboring seedlings.
Wait until your plants are an inch or two high before thinning. This way, you can thin to the recommended plants per square and eat the other plants as micro greens in a salad. (It makes it easier to kill strong seedlings if you’re going to eat them).
16. Know what to seed and what to transplant
Direct seed: To plant seeds directly into the soil.
Transplant: To plant seedlings (also called “transplants” or “starts”) that have already grown for several weeks indoors. Plants with a long growing season are usually transplanted for faster maturity.
If you plant a tomato seed in Colorado in late May, you most likely won’t see many tomatoes by the end of the year because of our short growing season (averaging only 157 days on the Front Range). Same with a pepper, herbs, and a number of other crops that should be transplanted instead of direct seeded.
It’s often difficult to remember which plants should be seeded or transplanted. In short, most cold season crops—besides broccoli, cauliflower, cabbage, onions, and a few others—should be seeded. Most warm season crops—besides beans, squash, and a few others—should be transplanted.
Sign up for “10 Garden Tips” and we’ll send you our Master Planting Bible – telling you every whether to seed or transplant each individual crop.
17. Place the garden where it gets maximum sunlight
Because of Colorado’s strong UV, we’ve found that five hours of direct mid-day light is more than enough to grow almost every vegetable that we offer.
(Because UV is strongest in the middle of the day, 2-3 hours of sunlight in the middle of the day is better than 3-5 hours of light in the late afternoon or early morning.)
With locations that receive less than five hours of light per day, we suggest planting Low-Light Crops. Download the list of low-light crops below.
Some of the low-light crops can grow with just 2-3 hours of sunlight, while others need 3-5.
Also consider planting low-light crops in places that are shaded within the raised garden beds—behind large plants that provide shade, under tomatoes, or even in the middle of the bed surrounded by crops that may over-crowd later in the season.
Here is the entire Low Light Crops Guide with Hour Requirements!
18. Set your expectations (low)
Are you a beginner gardener?
- Start by reviewing the 8 Stages of Clueless Gardening.
- Expect a 20% failure rate (that’s just how nature works)
- Adopt a more carefree Homer Simpson attitude when it comes to gardening. “Sometimes you just have to lower your expectations to avoid unnecessary disappointment.”
19. Mulch soil in the fall and keep it moist all winter if possible
There’s a reason soil is always covered with natural mulches in nature.
Mulch is a layer of material applied on the top of your soil. Mulch maintains a more constant soil temperature, provides nutrients for your plants, and keeps your soil moist throughout the summer. Mulching will also reduce weed germination and the amount of water needed for the plants.
Moist soil through the winter allows biology to release nutrients and maintain a healthy soil environment so your garden will be ready to rock in the spring.
20. Avoid buying unhealthy or root bound plants
Avoid purchasing transplants that are “root bound” (where the roots are bunched and intertwined, coming out the bottom of the pot). This indicates that the plants have been in their pots for too long.
Try to purchase dark green, healthy-looking plants, and if the leaves have started to turn slightly yellow, they are probably not worth buying (even if the price is marked down).
If the seedling is dry in its pot, water it thoroughly, until the root ball is saturated with water.
How to plant a transplant
- Handle the seedling gently, and touch it as little as possible. We suggest snipping off extra plants at the base rather than trying to separate them.
- If the seedling has been grown in a pot, turn the pot upside down, letting the plant stem pass between your second and third fingers, and tap firmly on the bottom of the pot with your other hand (sometimes squeezing the pot beforehand to loosen the soil is necessary).
- The best time to transplant is in the evening—when the soil is warm but the weather isn’t hot.
- Cover the root ball and potting soil completely with garden soil. Press the soil around the seedling, but not too firmly.
- Water the plant immediately after planting.
21. Harvest frequently to promote growth
Harvest cucumbers and zucchini when they are small. If you leave them on the stem, the plant is tricked into thinking it has successfully reproduced and its job is done.
Don’t let your plant get lazy – continually pull off the fruits to tell it to keep producing!
Harvest leafy greens continuously through the season. When the leaves of leafy plants are removed, it actually stimulates the plant to draw more energy from the soil to grow more leaves.
Vegetable gardeners frequently wait too long to harvest their vegetables. Greens will re-grow no matter how many times you harvest them, herbs are the same way, and cucumbers and summer squash always get too big. The tastiest, most premium vegetables are the small ones.
22. Remove plants when they’ve bolted
Bolting is when a vegetable crop “goes to seed”. A stem with seeds will shoot up through the middle of the plant. The plant is putting its energy toward reproduction—producing seeds instead of new vegetative growth.
A plant is done producing leafy vegetation when it bolts. Bolting is an irreversible process that indicates the plant is nearing the end of its harvestable lifetime.
Lettuce and many other crops tend to become very bitter and less tender after they have bolted. If you tear the leaves of lettuce, often times a milky substance will come out.
23. Use a square foot method of planting
We garden using the “square foot method” because it allows us to grow a lot of produce in a small space. To use the square foot method, hammer in nails around the edged of your bed, at one foot spacing. Use string or twine, woven around the nails, to make a grid that breaks your garden bed up into 1 square foot sections. See our Plants Per Square document to learn how to space plants in your garden based on the square foot grid.
But also remember that just because you can pack a lot of food into a small space with square foot spacing, doesn’t mean you can grow 15 kale plants in a square foot. Grow vegetables that are space efficient and be sure to give enough space to the veggies that need it.
24. Add solid organic fertilizer every year + liquid organic fertilizer if your plants are struggling
When you grow a lot of vegetables in a very small space, you will be pulling a lot of nutrients from your soil every year. It’s critical to amend you raised garden beds each year before re-planting, otherwise you will see your yields decrease dramatically.
We suggest adding a slow-release, organic, nitrogen-heavy fertilizer each fall with a very small amount of compost. Read a more detailed description of how to amend your soil.
During the season, it’s great to add a liquid (soluble) organic fertilizer if your plants are struggling (yellow lower leaves or very slow growth in the middle of the season). We use Age Old Organics “Grow”, as well as organic liquid fish.
Even better is to drench your soil with compost tea. This adds soluble nutrients and stimulates soil biology to release nutrients for your plants.