Plant Seeds: Types and Maintenance

THE SEED

A seed is a product of pollination among plants. It encloses an embryo in a hard coat which will grow and develop into a plant once germinated. In analogy, the human egg cell develops into a fetus, then a baby, while a seed germinates into a new plant.

Seeds are found in plant fruits. Examples would be the tomato that is harvested (most consider it a vegetable, but botanically it is a fruit), the corn cob (where the seeds, also known as grain, is attached), and many more. "Seedless" fruits actually have seeds, only that the plant was treated to significantly shrink the seed to the point that there is virtually no seed. Not all seeds can be sown for planting, for various reasons.

There are two types of seeds: orthodox and recalcitrant seeds. Orthodox seeds are the ones usually sold in the market in seed packs as they can be stored under dry conditions and stay viable for years. Recalcitrant seeds, on the other hand, are typically seeds of fruit trees. These cannot be stored like orthodox seeds as these will lose their viability over a short period of time once it's removed from the fruit. Sowing, then, is necessary right after removal from the fruit.

SEEDS IN THE MARKET

As mentioned, seeds sold in the market are typically orthodox seeds; hence, it can be stored and stay viable for years. Typically, seed viability is at two years, provided proper storage. There are two forms of seeds sold: open-pollinated variety (OPV), and F1 or hybrid.

Open-pollinated seeds are the ones that can be continuously planted true-to-type. Meaning, seeds produced by the fruit can be planted again for the next cropping season without significant difference from the parent. While this may give you a steady supply of seeds, do note that the genetic quality will be reduced overtime. Meaning the quality of the plant will also decrease. You will have to plant by the hundreds to maintain genetic quality.

Hybrid/F1 seeds, on the other hand, are of higher quality than open-pollinated varities. F1 varieties are products of two open-pollinated parentals, and by principle, are more superior than their parentals. The downside is that these will not produce seeds, or if they did, would not produce true-to-type offspring. In fact, the offspring would look weird or much deteriorated compared to open-pollinated ones. Which is better? It depends on your needs. Quality wise, choose hybrids. Sustainability wise, choose OPV. If you want to make a hybrid of your own, then use various OPV seeds. That, however, is another topic, and is not as easy as it sounds.

Seeds sold in the market can be grown hydroponically. Hydroponics does not require "special" seeds. Plants can adapt to the conditions they are subjected to (such as if they are grown in the soil or in water).

Greenthumb Gardening sells seeds that can be used for hydroponics. For a full list, click here.

GERMINATING YOUR SEED

There is no one-all method of germinating seeds. However, generally speaking, seed germination starts when it absorbs water. From that point on, various reactions take place inside the seed, wherein it prepares the embryo to emerge and fully develop into a new plant. Viability is the potential of your plant to germinate.This is also the % germination specified in the seed pack. This indicates the guaranteed chance that an individual seed will germinate. Actual results vary. Over time, viability decreases even with proper storage. The next thing to consider is vigor. Vigor is defined as the ability of the germinated seed to continue on to develop into a plant. To successfully produce seedlings, the seed must be viable and vigorous. The absence of one will lead to poor yield, while the absence of both will lead to no yield at all.

Specific treatments may be necessary for proper germination. Read about the plant species you are to plant for more information. 

Lettuce seeds at 85% germination rate and good vigor

HARVESTING SEEDS

Seeds from open-pollinated varieties can be harvested for replanting in the next cropping season. Simply cut open the fruit (usually in half) then scoop out the seeds. Clean off slime and other unnecessary materials using water. After which, air dry the seeds for at least a day. Do not oven dry. Store them in foil packs or paper envelopes, with proper identification (such as plant, variety, date harvested, etc.).
 

PROPER STORAGE

Whenever possible, seeds should be stored in a refrigerator (not freezer!) at temperatures below 15°C but greater than 0°C. Higher temperatures decrease viability over time. Seed packs must be kept unopened unless the seeds will be sown. This is to keep moisture levels low (as high moisture levels decrease viability). After getting your seeds, fold the opening to prevent spillage and moisture accumulation. Store in a tightly-sealed jar (like cookie jars) or container (with rubber gasket) with desiccant.

Seeds stored in a plastic jar with desiccant

Desiccant is also known as silica gel, or the sachet that is usually found in newly-bought shoes or bags. It must not be eaten, but it is non-toxic. You can buy these at hardware stores. Choose ones that have an indicator color.

Desiccant with blue indicator (dehydrated)

Desiccants can only absorb moisture at a certain extent; hence, once it is saturated with moisture, it can no longer absorb moisture. One way to find out is by using the color indicator. Some have a blue indicator that turn pink once saturated. Others are white in color, turning violet if saturated. Check with the hardware for more information. These, however, can still be reused, by evaporating the moisture in an oven or heating it in a cooking pan. Not to worry as this is non-toxic. The color will change back to its unsaturated color, indicating that it can absorb moisture once again.

Desiccant can be placed in medicine measuring cups covered by tissue

In the absence of a refrigerator, storage in a cool, dry, dark place will suffice. Examples would be kitchen cabinets or drawers. Be careful not to mix the seeds with food as some seeds may be treated with fungicide (to prevent germination diseases).


Typically, seeds can be stored with good viability for about (but not limited to) two years. There are other storage techniques that can extend viability for decades (for example, in International Rice Research Institute where they have a seed bank with large freezers, or the "Doomsday Vault" where seeds of important crops from countries around the world are stored), but that entails high cost and other treatments. Refrigerator storage will suffice.

That is all! Hopefully this article has given you a better understanding of seeds and how to take care of them.

The Setup Explained

Many may still find themselves unfamiliar with how a hydroponic setup works, or why it is set up that way. This article aims to explain the setup itself, plus the things you have to take note of, so you get to play around the specifications of your setup once you get a good understanding of it. For starters, a set of instructions is available here: Hydroponics Made Simple. The article will focus on the setup prescribed by the makers of SNAP.

THE CONTAINER

Any container will do, for as long as it is shallow and can hold large amounts of water. Usually (but not necessarily), the shape is rectangular, given that rectangular containers are widely available and that it is able to maximize space. Examples of these would be grape styrofoam boxes, wooden or plastic crates or pallets (or paleta), plastic shoe boxes, trough pots with saucer, etc. Other containers, such as pails, basins, baskets, and other similar materials, are allowed. For as long as your container can hold large volumes of water, then it fits the job.

In the case of styrofoam box, lining it with a sturdy polyethylene plastic sheet is necessary, since styrofoam is porous, and it alone cannot hold water. In our case, we also line the base with black garbage bag (aside from the plastic lining itself) in order to minimize algae growth.

Styrofoam box initially lined with black garbage bag

The plastic sheet recommended by IPB (SNAP producer) can be quite difficult to find (but if you shop at Divisoria, then you might find it), so an L or XL black garbage bag will suffice. Based on our experience, garbage bags can last for up to three months; after that, it will start to chip off and degrade. If you have the means to find the sheet, you might as well do, since it's MUCH sturdier than garbage bags.

Lined with 20x30x0.003 in clear plastic sheet

When using pails, be sure to have a porous cover so that air can circulate inside (don't copy the one in the pic where a plastic cover was used!). Alternatively, you can use an aerator just like in aquariums. Lastly, make sure that minimal light gets to the inside.

20L pail. Young tomato (back) and growing Jalapeno (front) planted

WATER

Tap water will suffice. Chlorine concentration is a concern for many, but note that chlorine is an essential element. Also, tap water that is released to the public has passed regulatory standards, meaning, chlorine concentration will have been within safe use. If this still bothers you, however, you may leave a pail of tap water outside for a day, to allow the chlorine to vaporize.

Rainwater can also be used, but only use rainwater at the middle of the rainy season and onwards, given that rainwater from the onset of the rainy season is actually acid rain, and acidic pH negatively affects plant growth.

As a general rule, if it can be watered to soil-based plants, then it is good for hydroponic usage. It's a plus (but not a requirement) that the water is potable or safe for drinking.

CUP

Any cup will do for as long as it can support your seedling and that it is deep enough to reach the water on your container. Around six slits will do. Slits can be made by using a serrated knife (for styrofoam cup) or a hot metal rod (for plastics). If using plastic, it is better to use a colored one instead of a clear one, to minimize light from entering the setup. 

 

8 oz. styrofoam cup

SUBSTRATE

Substrate serves as the support or anchorage of the young seedling. It does not, and should not, contribute to plant nutrition. Moreover, it should be inert, or simply put, must not be decaying or undergoing any biological process (i.e. matured). Ideally, the substrate should be porous to allow the plant to breathe. Any substrate will do for as long as it is not soil. Examples would be coco peat/coir/dust (they're all the same), sawdust, sand, gravel, hydroton clay, rockwool, sponge.

The amount of substrate used per cup should only be approximately 1/4 of the cup volume. Too much (say 1/2 of the cup) and the seedling would become "lazy," leading to slow growth. Too little and the seedling will have poor posture, and may possibly drown. Substrate erosion may be a concern. No need to worry as erosion is only minimal (unless you deliberately shake or disturb the water).

Coco peat used as substrate for lettuce seedling

SEEDLING

Seedlings should be sown in a soil-less medium. This medium can also serve as a substrate. Watering the seedlings with SNAP is only necessary at around 2 days after emergence. This is also to accustom the seedlings with SNAP solution.

Your seedling must be at least a week old or should have two true leaves before transplant. "True leaves" can be roughly defined as the leaves that emerge after the first two leaves of the seedling. Remember to pick the best-looking ones for best results.

Lettuce seedlings grown indoors

 SETTING UP

Now that you got all your materials, all you have to do is to set it up. Find a place that is sunny. Plants in general love the sun, so find the sunniest place at home (usually the North or South side). Also, your setup should have protection from rain. Although rain will not directly kill your hydroponic plants, it will definitely dilute your solution (requiring you to replenish it), and can drown the seedlings, leading to death. In our case, we've built a shed made with bamboo and plastic cover (bought in bookstores, but UV plastic is much sturdier and can last longer).

Hydroponic shed

Fill up your box with water up to the point wherein the level just hits the base of the cups (usually 1/2 inch). For the case of styrofoam box using 8oz. styro cups, approximately 10 liters is needed. Then add your nutrient solution. For SNAP, 1L solution requires 2.5mL A and 2.5mL B. Remember to mix one component first before adding the other. 

Water level should just hit the bases of the cups

Usually, pH adjustment is not necessary, but you may if you want. pH adjusting is usually for plants grown beyond one month.

Completed setup

From this point on, all you have to do is to wait for the plant to grow. Refilling isn't usually necessary, but if the situation calls for it (when water level has receded but root growth is poor) then you may have to refill up to a level where the roots can have contact with water. If refilling is needed one week before harvest, just add water. Nutrients are not that necessary at that stage.

White-colored roots show good aeration and health

That's all! We hope that you were able to understand how the setup works. Other related articles shall follow. For more inquiries, you may leave us a message at facebook.com/greenthumbmnl.

Greenthumb Gardening sells some of the items mentioned here, such as SNAP Hydroponics solution, coco peat and seeds. For a full list of products offered by GTG, and the order process, click here.