Knowing When to Start Seedlings on Fertilizer and Nutrients
Delicate seedlings need a little extra attention and knowledge to help them grow big and strong. Follow Kate Van Druff’s advice on growing conditions, nutrients, and fertilizer to get your seedlings to the next level.
Few things about gardening are as gratifying as watching a tiny seed become a flourishing plant. Flowers, herbs, fruit, vegetables, ornamentals — the possibilities of what you can grow are endless and the journey is memorable year after year.
Many variables come into play as simple seeds start their lifecycles. Starting seeds indoors or outside relies on factors such as the climate and natural or artificial lighting conditions. The timing of planting also comes into play, where seedlings started indoors too early in the season and without suitable lighting can become leggy and thin rather than healthy and robust. Of course, the selected planting medium can also impact the quality of the seedlings you grow, where some potting mixes contain nutrients right from the start and others are merely, well, dirt.
Finding the perfect balance of growing conditions and nutrients isn’t always easy.
This article will help you to discover the best nutrients and fertilizers for your seedlings and when you should apply them.
Understanding Essential Macronutrients for Seedlings
Introducing fertilizers and nutrients for seedlings can boost growth and production for your plants. Plants require many different nutrients to thrive, particularly oxygen, hydrogen, carbon, which they get through water and air, as well as potassium, phosphorus, and nitrogen, which need to be added through fertilization. These key nutrients tend to be the most important, but you’ll also want to consider micronutrients that can also fortify your seedlings for their best potential.
As the single most important nutrient for plants, nitrogen is responsible for plant growth, and more specifically leaf growth, plant size, and overall health. Plants supplied with sufficient nitrogen will grow strong and quickly. Nitrogen also plays a key role in photosynthesis, serving as a component of the chlorophyll molecule that makes plants green. As seedlings grow into larger plants, the demand for nitrogen also grows.
Also vitally important, phosphorus aids plants in creating strong roots, making seeds, and producing fruit, vegetables, and flowers. Phosphorus also aids in photosynthesis by facilitating the plant’s energy transfer and allowing plants to use or store energy. Demand for this nutrient is greatest during seed germination and early life, as well as during fruiting or flowering. General weakness and stunted growth are two signs of phosphorous deficiency in plants.
The next most essential plant nutrient after nitrogen, potassium helps with many aspects of plant growth and development, such as a plant’s size, shape, and color, not to mention the taste of any produce. Adding potassium to the soil helps plants with the protein synthesis process as well as the activation of growth enzymes.
Growth-related issues such as leaf loss, cholrosis (scorching of leaves), weak root systems, and stunted growth may present when plants become too deficient in potassium.
Seedlings and plants also tend to need a large amount of magnesium, calcium, and sulfur. These complete the list of essential macronutrients commonly required for plants and crops.
– Calcium strengthens plant tissues and helps to neutralize soil and plant acidity. Calcium in the soil also helps improve water penetration and decrease the soil’s salinity.
– This nutrient also helps give plants their green color, increasing the intake of phosphorus, increases chlorophyll, and allows better CO2 absorption.
– Sulfur helps plants produce seeds and resist disease. This nutrient also promotes growth, production of chlorophyll, and helps in producing proteins, amino acids, and enzymes.
Together, these six essential macronutrients aid in the creation of chlorophyll, which helps plants convert light into energy for photosynthesis. The process of photosynthesis allows plants to take sunlight, CO2, and water and turn them into sugar and oxygen. The glucose created then affords plants the ability to use that energy to grow and repair damage or to store it for later. Better photosynthesis enables plants to be more prolific, with better growth and larger and more bountiful yields. Ensuring proper macronutrient fertilization has a direct impact on plant growth and your future harvest potential.
Best Micronutrients for Seedlings
After you monitor and amend the soil for proper macronutrient content, remember that many diverse nutrients can benefit your plants. As you become a more experienced gardener, you may begin to recognize signs that your plants are craving specific nutrients. You should consider these other key micronutrients to inspire balanced nutrition for your plants.
supports a plant’s membranes in terms of structure and function. helps in vitamin A production as well as protein synthesis along with other growth processes. aids in food production, energy transfer, and overall growth, to name a few. supports quicker germination, photosynthesis, and aids in various metabolic reactions. supports nitrogen fixation. is especially vital as it supports high yields in crops.
- Nickel is essential in urea conversion.
- Chloride supports plant energy reactions.
Plants need lesser concentrations of these micronutrients, yet their presence can have a great impact. Even a slight deficiency in one micronutrient can impact a plant’s overall health and growth. Adding organic compost can be an effective way to increase micronutrients in the garden.
When Can Seedlings First Have Nutrients?
The soil where your seeds start can have an impact on the future growth of your plants. Generally speaking, seedlings won’t need their nutrients until their first full set of true leaves sprouts. Those first leaves that emerge, called cotyledons, are actually part of the seed and will deliver nutrients to get the seedlings started. The cotyledons feed the plant, so you don’t necessarily need to start feeding right away.
Once the true leaves appear, you may wish to transfer the seedlings from their current spot to a larger pot or a cell pack. At this point, you can use some potting mix with built-in nutrients, or you may wish to choose your own fertilizer to apply at regular intervals. A diluted, water-soluble fertilizer can deliver essential nutrients for the young plants as they grow. Dissolving fertilizer in water makes it so easy to feed your plants as needed. You can monitor your seedlings to decide if lightly fertilizing once or twice per week works best. Signs of over-fertilizing may include yellowing leaves, slowed growth, wilting, or buildup of salt. If you’ve used a potting mix with nutrients already mixed into the soil, proceed slowly with any additional fertilizing efforts to avoid harming the plants.
Nourishment Timeline for Baby Plants
Germinate seeds in starter containers or packs. Choose between plain potting medium or nutrient-enriched potting mix.
- Plain Potting Mix: After the first set of “true leaves” emerges, apply diluted, water-soluble fertilizer only to seedlings not already fortified with nutrient-rich soil.
- For a more organic fertilizer route, consider using nitrogen-rich blood meal, phosphorous-rich bone meal, and potassium-rich kelp meal.
- As another natural option, you may also wish to make your own compost.
- Nutrient-Rich Potting Mix: When starting from potting mix with added fertilizer, wait six to eight weeks and then supplement the nutrient-rich potting mix with a little fertilizer.
- Look for clues that your plants may be craving nitrogen, such as yellowing or slowed growth before adding more fertilizer.
Words of Caution When Fertilizing Young Plants
Using too much fertilizer too early on can burn young plants and their roots. It’s best to proceed with caution, adding a little fertilizer at a time and increasing as the plants grow and mature. Remember, you can always add more fertilizer, but you can’t really undo overfertilization.
You may also wish to have your soil tested prior to fertilizing so you know about any nutrient deficiencies that you should work to correct. Your healthy plants and yields will thank you for it!
Read also: Super Starts: Healthier Transplants for Happier Harvests
It may be true that anyone can stick a seed in a bit of soil, add some water and sunlight, and watch it grow. There’s a lot more to it, though. Pay attention each planting season to discover what works best as you familiarize yourself with each different plant you like to grow and which applications produce the best results.
With a solid understanding of nutrients, fertilizers, and growing conditions, you can cultivate stronger, healthier, and more vigorous plants year after year.
How to use nutrients and fertilizers to grow marijuana plants
A cannabis plant needs many nutrients, and pulls these from the soil. Left on its own, with good soil, plenty of light and water, and a temperate environment, a weed plant will grow fine, but nutrients will help the plant thrive and grow healthy and strong.
What are cannabis nutrients?
Growing high-quality weed requires more nutrients, or fertilizer, than most common crops.
Outdoor cannabis growers typically add powdered nutrients to soil when transplanting a weed plant outside. This will give the plant all or most of the nutrients it needs for its entire life cycle, and if you want to add more nutrients to plants later, you can add them to the top of soil—called “top dressing.”
Indoor growers typically use liquid nutrients and mix them in with water before watering plants. Using liquid nutrients is usually more time consuming, as you typically have to measure and mix them in water 1-2 times a week.
We recommend not using nutrients made for indoor growing for outdoor plants, as they are usually composed of synthetic mineral salts and can damage soil bacteria.
What nutrients does a cannabis plant need?
Your marijuana plants need the following primary nutrients, collectively known as macronutrients:
- Nitrogen (N)
- Phosphorus (P)
- Potassium (K)
These micronutrients are needed as well, but in much smaller quantities:
- Calcium (Ca)
- Magnesium (Ma)
- Sulfur (S)
Other micronutrients that occur in very small amounts and that you don’t hear about as much include: boron, chlorine, copper, iron, manganese, molybdenum, and zinc.
Additionally, cannabis plants derive these non-mineral elements from air and water:
Cannabis plants need different amounts of these nutrients throughout the different stages of growth: more nitrogen during vegetative growth, and more phosphorus and potassium during flower for bud production—also called “bloom” nutrients.
Nitrogen is mainly responsible for a cannabis plant’s development during the vegetative stage of its life. It’s an essential part of chlorophyll and without it, a plant can’t turn sunlight into energy and it won’t be able to grow.
Nitrogen is also part of amino acids that act as building blocks for proteins in a plant. Without the necessary proteins, your cannabis plants will be weak and frail. Nitrogen is also a part of ATP, which allows plant cells to control the use of energy.
Nitrogen is also necessary to create nucleic acid, an essential ingredient in DNA or RNA, and without it, cells won’t be able to grow and multiply.
Phosphorus is important for producing large, healthy buds. The key role of this element is to help make nutrients available for the plant to uptake. These nutrients are used to build the structure of a plant as it grows from its roots to its flowers.
Without adequate phosphorus, marijuana plants will show signs of undeveloped roots and might not even flower. Early signs of phosphorus deficiency shows up as a purple hue in the veins of leaves.
Potassium has a number of jobs that largely help regulate the systems that keep a plant healthy and growing. It plays a large role in osmoregulation, the passive regulation of water and salt concentrations in the plant. Potassium accomplishes this by controlling the opening and closing of the stomata—the pores in the leaves—which is how a plant exchanges CO2, H2O, and oxygen.
Potassium also triggers the production of ATP, which works to store energy produced in photosynthesis by creating glucose. This glucose is then used as energy for the plant as it grows. Without sufficient potassium, you will see weak plants starved for energy that appear burnt because they are unable to successfully regulate the exchange of CO2, H2O, and oxygen.
Calcium is responsible for keeping the structure of cell walls in a plant together. Without calcium, new growth won’t develop properly and the plant won’t function as it should. New growth will be stunted, leaves will curl, and rusty spots will show up on the plant.
Magnesium acts as the central molecule in chlorophyll and without it, plants aren’t able to generate the glucose from photosynthesis. No magnesium means no energy can be converted from sunlight.
Once magnesium has helped create glucose, it helps metabolize glucose to make it available for the plant to grow. Without sufficient magnesium, you will find yellowing leaves, with discoloration reaching the veins as well.
How to use and mix cannabis nutrients
Nutrient solution bottles and fertilizer bags will indicate how much of the three main nutrients are in the product, in the form of N-P-K: Nitrogen, phosphorus, and potassium, For example, a product that says “10-4-4” will contain 10% available nitrogen, 4% phosphorus, and 4% potassium by weight.
A general rule of thumb is that a vegetative fertilizer should have high nitrogen, low phosphorus, and moderate potassium: for example, 9-4-5. As a plant transitions into flower, taper off the nitrogen and focus on phosphorus and potassium—seek a ratio around 3-8-7, for example.
Products are also generally divided into “grow” solutions, high in nitrogen needed for vegetative growth, and “bloom” solutions, high in phosphorus for flower development. You can stick to these general terms if you don’t want to get bogged down with numbers.
In the final week or so before harvest, be sure to give your plants only water to clear any nutrient buildup in the buds—this is called flushing.
Liquid nutrients are typically used for indoor growing, but can be used outdoors too. Liquid nutrients are used for weed plants in soil, hydroponics, and other grow media, and can be pushed through drip lines, misters, and hoses for easy and efficient delivery.
Because liquid nutrients are readily available to a cannabis plant’s roots, they are fast-acting, meaning they can damage plants if you feed them too much.
To use liquid nutrients, you’ll need a separate water tank, such as a dedicated garbage bin, to mix them into water. You’ll also need to know how much water is needed for all your plants. Depending on the amount of water you need, add the correct ratio of liquid nutrients according to the bottle’s directions.
When using liquid nutrients for cannabis plants, it’s important to have a watering schedule to write down and track:
- How much water you use
- How many and what kind of nutrients you use
- How frequently you water
You don’t want to use liquid nutrients every time you water—use them every other watering, or two waterings on, one off. It depends on the complexity of your soil and the health of your plants. Too many nutrients will damage your plants.
Giving weed plants the proper amount of nutrients requires careful monitoring. Many growers start at a solution dose lower than recommended and work their way up until plants respond optimally. Too little nutrients and the plants will have stunted growth, while too many can lead to nutrient burn and lockout.
Check your pH
It’s important to get a pH meter to check the pH level of your water when mixing nutrients. Cannabis prefers a pH between 6 and 7 in soil, and between 5.5 and 6.5 in hydroponic media. Letting the pH get out of this range can lead to nutrient lockout, meaning your plants are unable to absorb the nutrients they need, so be sure to test your water regularly and make sure the nutrient mix you give plants falls within the desired range.
Comparing nutrient and fertilizer brands
There are many different cannabis nutrients out there and it may be overwhelming knowing where to start. Here’s a breakdown on some of our favorites.
|General Hydroponics||Their Micro, Grow, and Bloom are gold standards in nutrients, and great for beginners and pros alike.|
|Botanicare||Another solid nutrient provider, their Grow and Bloom formulas keep things simple and plants happy.|
|Dyna-Gro||Their Pro-TeKt is great for adding to plants during flowering.|
Organic cannabis fertilizers
Organic fertilizers are nutrients that come from organic sources such as animal and vegetable waste. They also include sediments like glacial rock dust and gypsum that contain beneficial minerals for the soil and plant. They are common for outdoor growing and usually come in powder form.
Organic fertilizers and nutrients can be more forgiving than liquid nutrients. They usually contain less immediately soluble nutrients and more elements that are beneficial to soil organisms.
Most of these fertilizers can be purchased cheaply at your local nursery and then mixed into soil before potting outdoors. Done correctly, you’ll only need to water your plants throughout the growing process, as all nutrients are in the soil.
We recommend these organic fertilizers:
- Nitrogen: Worm casings, blood meal, fish meal, bat guano
- Phosphorus: Bone meal, rock dust
- Potassium: Wood ash, kelp meal
- Calcium and magnesium: Dolomite lime
Commercial soil blends also exist that already contain the proper mix of these nutrients.
Benefits of organic fertilizers for cannabis plants
One of the best things about organic fertilizers is they improve the soil while also improving the quality of your plants. Other benefits:
- The slow release of nutrients protects plants from too many nutrients
- Over time, organic fertilizers will improve the quality and diversity of life in soil
- Improved airflow and water retention in soil
- Renewable and sustainable
- Organics stay in the soil with a lower chance of nutrient run-off
Some growers also find that growing organically increases the flavor profile of finished cannabis as well as increases yields.
The fertilization process can repeat itself year after year as the soil continually improves—next year, your soil will be even better than this year’s.
Using organics is also great if you want to be more in-tune with your natural environment. Organic fertilizers are readily available from renewable sources and are an earth friendly option.
Disadvantages of organic nutrients for cannabis plants
There are some complications in working with organic fertilizers. The main issue is if your weed plants have a nutrient deficiency, it takes longer for a plant to absorb organic powder nutrients, which can increase the damage to plants. Liquid nutrients act much quicker. Other disadvantages:
- They take time to be absorbed by the plant
- Require microorganisms to break down nutrients, which may slow in colder temperatures
- Can introduce insects and pests
How to make compost tea for marijuana plants
Compost is filled with beneficial microorganisms and nutrients, and you can take it one step further by steeping it in aerated water. This process, called “compost tea,” extracts the microorganisms and soluble nutrients into a water “tea” solution.
The goal of compost tea is to introduce nutrients, fungal colonies, and beneficial bacteria to either the soil or foliage of a marijuana plant to aid growth and protect it from harmful disease, promoting bigger, stronger, and more resilient plants.
Compost tea should never be a 100% replacement for nutrients, but it can be a great complement to other nutrients.
You can add compost tea to weed plants by:
- Spraying it on leaves
- Applying it to soil
When applied to soil, you’re adding to the soil food web by introducing a healthy population of microorganisms that are aerobic in nature. These organisms hold nutrients, aerate soil, aid water retention, increase nutrient absorption in the cannabis plant, help grow healthy roots, and help prevent diseases.
However, the benefits of compost tea are debated in the agricultural world. Many gardeners report quality results when using it, while others see no more benefit than applying straight compost. The uncertainty lies in whether or not growing and developing populations of microorganisms in the tea can actually benefit plants and prevent disease.
Compost tea recipe for marijuana plants
A healthy compost tea pulls soluble nutrients and microorganisms from compost, including bacteria, fungi, and protozoa.
Here are five key compost tea ingredients recommended by the Beneficial Living Center located in Arcata, California, to create a successful tea that will work best for your cannabis.
- Compost: A healthy compost should have large populations of microorganisms and nutrients, and sourcing it locally will ensure organisms are local pathogens. Compost that contains developed mycelium (fungal colonies) populations will help aid the development of fungal growth in the tea.
- Worm Castings: These byproducts expelled from a worm after digestion provide a high density of nutrients in a broken-down, refined form readily available for plants. Worm castings also introduce microorganisms.
- Fish Hydrolysate: This is produced by breaking down fish and crustaceans to create a nitrogen-dense product. Crustacean exoskeletons also have chitin, which works as an immune booster for plants. Fish hydrolysate also helps feed and increase fungi populations.
- Kelp: This serves as a source of food for fungi that grow while the tea is brewing. It’s also thought to provide a surface for fungal colonies to attach to and develop.
- Molasses: Serves as a source of food for bacteria that grow while the tea is brewing.
How to make compost tea in 5 steps
Build a compost tea brewer
Before building a compost tea brewer, you need to consider the size of your cannabis garden. Most homegrows use 5-gallon buckets. On the outside of the bucket, you’ll need to have an air pump connected to an aerator device at the bottom. The aerator and air pump will oxygenate water so microorganisms can breathe.
You’ll also need a 400-micron mesh bag to place ingredients for the tea. While you can buy pre-built tea brewers, you can also easily make your own for cheap.
Build your schedule
Tea brewing takes time, so it’s important to figure out when you want to apply the tea. Most teas generally take 24-36 hours to brew. You don’t want to let your tea brew for too long because the microorganism populations will develop to a point where they won’t have enough oxygen or space to live, and will begin to die, which can damage your tea.
Only start a tea when you can apply it within 36 hours of brewing it. When using as a spray, apply in the evening or morning when the temperature is low and without direct sunlight. This period is also when the stomata—pores in the plant’s foliage—are open to receive nutrients.
Fill your compost tea bag
When creating a first batch of tea, keep the solution simple. If you use city water, allow it to sit and breathe so chlorine can break down. Once your tea is brewing, keep it out of direct sunlight and make sure the air pump is running and oxygen is being pushed through the water.
Finalize your compost tea
There are multiple products that can be added in the middle of your brewing process, toward the end, or right before application: Food for bacteria and fungi can be added halfway through the brewing process to increase the growth of microorganisms; products like SeaGreen and Actinovate can be added before the tea is applied to plants for additional benefits.
Applying compost tea on cannabis
The tea can be applied to roots or as a spray on leaves of your cannabis plants. Dilute the tea with water at a ratio around 1:20 when applying it to roots. A basic tea can’t harm or burn your plants, so you can apply a potent dose freely. As a foliar spray, compost tea is generally diluted with water at a 1:2 ratio.
Don’t put compost tea through drip irrigation lines because it will clog them up over time. It’s important to either gravity feed the tea or use a diaphragm pump—as opposed to a centrifugal pump—to avoid chopping up and disrupting the active microorganisms when watering.
When to Start Using Fertilizers with Cannabis
In this article we’re going to talk about when to start using fertilizers with cannabis. People always ask us when they should start using fertilizers on their plants, but honestly it depends on your grow method, the strain and the phase that the plant is in.
Depending on the phase your grow is in your plants are going to need certain nutrients in higher proportions; they need more Nitrogen in growth, and phosphorus and potassium for the flowering period. Cannabis plants absorb large quantities of these nutrients as well as others, so if they don’t get them through irrigation then they’ll probably end up showing deficiencies through stains on the leaves.
To start using nitrogen during the growth phase you’ll need to wait for your little plant to grow the roots out enough so that it becomes slightly stronger. It won’t need much more than some humidity to germinate and grow during the first few days, but once it begins growing aster then you’ll need to start using a growth fertilizer.
You should begin off with small dosages; if your product says 4ml/L for adult plants then you need to start off with 1ml/L, and only begin using it once the leaves on your plant have three points. Once those leaves appear you can start using your growth fertilizer in the irrigation water. Once the plant begins growing more then you should raise the dosage until you reach the maximum milliliters allowed, and always use it with every second watering.
For the rest of the grow, regardless of what products you use, you will need to use them on every second watering or else you’ll burn out the roots. If you notice the plant getting yellow then you can use fertilizers twice in a row, but if it gets a dense dark green color then you’ll need to lay off on the fertilizers for a couple of waterings.
Once the female flowers begin showing then you’ll need to begin using flowering fertilizers. Just like in the growth period, you’ll need to start off little by little until you reach the maximum milliliters stated by the fertilizer manufacturer, alternating between pure water and fertilizers.
Each brand has a different range of products, so depending on the brand you go with you’ll need to use more or less products for both growth and flowering, although in this article we’re just talking about WHEN to use them.
If you buy a product with root stimulants in it then you should use it during the first two growth weeks and for two weeks after every time you transplant. If you have a flowering stimulant then you’ll need to use it once you flip the lights to 12 until the first flowers start appearing.
If your chosen range of liquids has a fattener with a high PK you’ll need to use it during the last phase of the flowering period, the fattening period.
Author: Javier Chinesta
Translation: Ciara Murphy