The Revolutionary Seed-starting System for Years of Perfect Germination -- Now in JUMBO Size!

Park's Original Bio Dome with 40 Jumbo Cells

Item # 06456
Buy 2+ at $29.95 ea
Available to ship.

This "mini greenhouse" lets you control climate and conditions for best germination!

Bigger, healthier, better-rooted seedlings every time -- the easy way!

A Park Seed Exclusive!
Other Items in this Series:
Park's Original Bio Dome 60 Cell Seed Starter Park's Original Bio Dome with 18 Whopper Cells Bio Dome for Beginners Kit Pro Dome Mini Greenhouse
Item Form Accessories
Color Original
Size 40-Cell
Restrictions *Due to state restrictions we cannot ship to the following:
Canada, Guam, Puerto Rico, Virgin Islands
Overall Rating: 5 Stars
Average Based on 7 Reviews Write a Review
Excellent for Starting from Seed
Paul R. Smith from TN wrote (April 10, 2015):
I bought three of these and planted Zinnia and Marigolds. Three days later 2/3 had germinated and after five days all but three or four had germinated. I put them in a sunny window and watered once in three weeks and will transplant tomorrow. Best method for germinating seeds I have ever used. I ordered more sponges and Shasta Daisy and Black Eyed Susan for a second planting. I am sold on this product.
Tidy Prep...FAST Germination!
Nancy Goss from WI wrote (February 26, 2015):
This is my first time using the Bio Dome (with a bottom heat mat) and I have to say I am impressed! I started my Broccoli, Tomatoes, Chinese Cabbage, Bok Choi and Coreopsis on February 24th. Today is the 26th...just 48 hours...and all are sprouted. Looking forward to using the other two Bio Domes for the next round of seeds in two or three weeks. Superior product!
Great Product, worth the money, little mess
Dale76 from PA wrote (March 31, 2014):
If I would of caught my wife planting seeds on our dinning room table it wouldn't been good! She caught me... soak the cells (more like a quick dip), place in the cell, seed and done. Well crafted, durable, don't jump on it, it'll last a very, very long time if taken care of; and that shouldn't be alot of effort!
My seedlings are awesome
Kaley from PA wrote (March 20, 2014):
This is my second time starting seeds. The first time was not with the biodome, and it happened to go horribly due to some mixture of too much and too little top watering. With the biodome, I have not had any problems. Almost every seed sprouted (except some 3 year old pepper seeds which I wasn't sure about anyway), and they sprouted relatively quickly too, giving me very little time to worry about whether I did it wrong. The only addition I made was to sit a little fan next to my tray to give the baby plants a little exercise.
Super easy, Super great!!
Sozo, organic backyard raised bed gardener n Central Fl. from FL wrote (April 12, 2012):
I bought this to start various cultivars of peppers. Some peppers can be difficult to germinate and are just really fragile when they are small. The biodome worked so well, the germination was about 99%! I had about or three seeds that did not sprout but I think the seeds were duds. Once sprouted, they all grew very well with the fert that came along with the dome. Transplanting the plugs to containers (after they are big enough) is way easy too. Directions are simple and easy to follow. Very clean -n- neat. I definitely recommend this for starting seeds.
Fast germination
Carmen from MN wrote (March 02, 2012):
I now have 4 of the Bio Domes. They are much better for starting seeds than the regular trays with flimsy tops. I just wish I could buy just the bottom trays along with the additional foam inserts since the domes are only needed for a short while and they take up storage space. With the additional trays I could start many more seed, since I grow both early and regular season vegetables.
The best seed starter I've ever used
Adrasteia from FL wrote (October 22, 2011):
I've used other cheaper seed domes and seed-starting products like the Jiffy pellets, but none could compare to this. Other products yielded maybe a 30-40% success rate at best, and the plants were small and roots were weak. These domes consistently had a 90-95% success rate with seeds of all varieties that yielded strong roots and thick healthy plants. I planted tomatoes, jalapenos, banana peppers, pumpkins, watermelons, lettuce, spinach, carrots, onions, cilantro, and countless other vegetables and dozens of flower varieties, all in the same two domes. I'm back today to buy 4 more of them.

What are the differences between the various Bio Domes: 60-cell, 40-cell, and 18-cell?

The original 60-cell Bio Dome has a 60-cell planting block with 60 Bio Sponges and will produce 60 plants at one time. The 1" wide by 2 ¼" deep cells are larger than average, and a spacious 1 3/8" apart. The bio-sponges are the same size as the cells; 1" wide by 2 1/4" deep. You can grow and keep plants in the 60-cell bio-dome for 6-8 weeks before transplanting. Many varieties will just need 6 weeks until transplanting. Tomatoes and peppers would appreciate the full 8 weeks before transplanting. So, the original 60-cell bio-dome would be great for starting all of your favorite vegetable and flower seeds, with a larger number of plants produced at one time.

The 40-cell Bio Dome has a 40-cell jumbo planting block with 40 Bio Sponges and will produce 40 plants at one time. The cells are wider and deeper than the original 60-cell planting block and provide good spacing to maximize air flow. The cells are 1 1/4" wide by 2 1/2" deep. The Bio Sponges are also 1 1/4" wide by 2 1/2" deep. You can grow and keep plants in the 40-cell bio-dome for at least 6-8 weeks and some for up to 9-10 weeks, because of the wider spacing and cell/sponge size. It too would be excellent for starting all your favorite vegetable and flower seeds, with the added benefit of giving more room and time for larger plant development.

The 18-cell Bio Dome has an 18-cell whopper planting block with 18 Bio Sponges and will produce 18 plants at one time. It has the largest cells of any of the Bio Domes we offer and is great for growing extra-stocky transplants and even for rooting cuttings. The cells are 3" tall by 1 3/4" wide. The Bio Sponges are also 3" tall by 1 3/4" wide. You can grow and keep plants in the 18-cell Bio Dome for at least 8-10 weeks and some for up to 12 weeks, giving the maximum amount of growing time and spacing between plants as compared to the 60-cell and 40-cell Bio Domes. If you are looking to grow your favorite vegetable and flower seeds into large, stocky transplants for setting out in spring, then the 18-cell Bio Dome is the one you want to buy. It would be excellent for growing Tomatoes and Peppers.

How much water should be put in the Bio Dome and how often?

The beauty of the Bio Dome is that you cannot overwater! You just keep water in the tray and float the block. The larger the seedlings get, the more water they will use and you will need to add water more frequently as they grow. Initially, during germination, you may not have to water as frequently, because minimal water is being used and Bio Sponges will stay moist longer, so you may only have to water once every 1-2 weeks. Later, as plants grow and water use is greater, depending on the room temperature and the amount of light received, you may have to water more often -- possibly 1-2 times a week -- or as often as required to keep the sponges moist.

Bio Dome Instructions

Remove the Bio Dome Styrofoam blocks from the plastic wrap, keeping upright so that the plugs do not fall out. The plugs are ready to sow as they are!

For most seed types, place seeds into the pre-dibbled hole at the top of each plug. Tiny seeds that need light to germinate should be sown on the surface of the plug, not in the hole. Seeds do not need covering in the Bio Dome plugs. Each plug provides the optimum environment for germination.

Place the germination units in a favorable location as indicated on the seed packet.

To moisten the plugs it is best to soak them from the bottom. This can easily be done by putting water into the under trays provided and floating the Styrofoam blocks. It is not possible to over-water by this method.


Place the dome on the Bio Dome to maintain the humidity around the planted plugs. Keep moist until the seedlings emerge. Because of their composition, the plugs retain just the right amount of water. Less frequent watering may be needed and there is no danger of overwatering as with some other germination methods.

When you see that germination has started, open the vents on the Bio Dome. After the seedlings have emerged, remove the dome and provide more light. Use a grow light kept 1”-3” above the plants as they grow. This will prevent the seedlings from stretching and producing a weak plant. Brighter light will help keep the seedlings short and stout. Water as often as needed to keep the plugs moist.


Once the seedlings have developed their first set of true leaves, mix a weak fertilizer solution, following directions on the free fertilizer packet included with your Park's Bio Dome Seed Starter shipment. Water with this solution, instead of plain water; until the next set of true leaves develop. You can increase the concentration of the fertilizer solution once the second set of true leaves develop.

When the second true leaves appear the seedlings are strong enough to be transplanted. Transplant your seedlings, plug and all. To remove the plug from the block, poke out from the bottom and plant them where the plants are to grow.

If weather or timing delays your transplanting, often the roots will emerge from the bottom of the plugs. Prop up the blocks to allow some air space beneath them, until you are able to transplant but don't allow the plugs to dry. This builds a stronger root system within the plug.